Дисертації: "Concrete slabs Thermal properties"

1

Rao, Hejamadi Dhananjay. "Thermal stress in concrete slabs under different constraints." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4752.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains viii, 127 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 123-126).

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2

Marmash, Basem Ezzat. "The properties of recycled precast concrete hollow core slabs for use as replacement aggregate in concrete." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13501/.

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The dumping cost of wasted concrete including the rejected units in precast concrete plants is expected to keep rising as the production increases. The waste material from precast concrete hollow core floors (hcu) is high grade and uncontaminated material. This research work was carried out to investigate mainly the strength and other engineering properties of high strength concrete made with recycled concrete aggregate derived from rejected hcu. Three major categories (based on a questionnaire) were investigated: (i) Type of crushers and the crushing method, (ii) The properties of RCA output from these crushers, (iii) The performance of fresh and hardened concrete, including prestressed concrete, with these RCA. The input material for the crushers was from the same origin of disposed hcu's. The waste concrete was crushed to -14 mm using three different types of crushers - the cone, impact and jaw crushers. The recycled material was separated into fractions of 14 mm, 10 mm and - 5 mm, and tested for physical and mechanical properties relevant to use in concrete. Concrete was then made using zero (control mix), 20% and 50% replacement of recycled coarse (RCCA), recycled fine (RCFA) and mixed (RCCA+RCFA) aggregates. All three crushers produced acceptable shape and strength of RCCA. Some properties are competitive to that of natural limestone aggregate. RCFA was much coarser than river gravel and just complied with the British Standard coarse grading limits. The impact crusher performed best with regard to most aggregate properties, e. g. flakiness, strength and water absorption, but has a disadvantage in producing a large amount of fine-to-coarse RCA. Concerning shape and strength, RCA showed similar properties, and in some cases better, than the conventional limestone aggregate. The water absorption for RCA is 3 to 4 times greater than the natural aggregates. For that reason an extra amount of water (called free water) will be added to the mix to compensate the water absorptions for aggregates. Some proportions of this extra added water may not be absorbed by the aggregates and will float to interrupt the design W/C ratio and caused it to increase. The slump value of fresh concrete made with RCA varied widely depending on the percentage and type of replacement, and the type of crusher. The compaction factor of fresh concrete made with RCA was more consistent and logical. Compressive strength of concrete made with RCA were generally within ±5 N/mm2 of the control. For tensile strength, RCA showed similar performance to that of natural limestone. The SS density of concrete with RCA is lower than that of the control concrete and is lower if the replacement percentages increase. Using RCFA causes higher bleeding rate and considerably reduces density and strength, and the severity increases as the replacements of RCFA increases. Using natural limestone aggregates with RCFA will minimize this poor behaviour and maintain the strength to certain extent. However joining RCCA with RCFA will not limit the poor behaviour and is not recommended. For bonding reinforcing bars most methods indicated that high replacement (100%) of CA cause some reduction in bond strength. In pretensioning wires the RCA concrete had a better performance in bond but some reduction was still reported. Prestressed X-shape beams were used to assess the effects of using of RCA on the performance of hollow core slabs. For 20% RCCA replacements, the prestressing loss, deflection and X-beam flexure crack failure were similar to the standard X-beam, at least and within the design limit. However at higher replacements (50%) some deterioration starts to reveal and the effects are even greater when using a combination of RCCA and RCFA.

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3

Saad, Ahmad. "Material properties of concrete used in skewed concrete bridges." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-54412.

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This thesis has discussed both properties and geometry of concrete slabs used in bridges. It gave understanding on behavior of concrete in both tension and compression zones and how crack propagates in specimens by presenting both theory of fracture and performing concrete tests like tension splitting, uniaxial compression and uniaxial tension tests. Furthermore, it supported experimental tests with finite elements modelling for each test, and illustrated both boundary conditions and loads. The thesis has used ARAMIS cameras to observe crack propagations in all experimental tests, and its first study at LNU that emphasized on Brazilian test, because of importance of this test to describe both crushing and cracking behavior of concrete under loading. It’s an excellent opportunity to understand how concrete and steel behave individually and in combination with each other, and to understand fracture process zone, and this has been discussed in theory chapter. The geometry change that could affect stresses distributions has also described in literature and modelled to give good idea on how to model slabs in different angles in the methodology chapter. Thus, thesis will use finite elements program (Abaqus) to model both experimental specimens and concrete slabs without reinforcement to emphasize on concrete behavior and skewness effect. This means studying both properties of concrete and geometry of concrete slabs. This thesis has expanded experimental tests and chose bridges as an application.

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4

Srinivasan, Shiva. "Characterization of stresses induced in doweled joints due to thermal and impact loads." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2186.

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Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains x, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 108-113).

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5

McNicol, Thomas James. "Examination of Drying and Psychrometric Properties of High Water-Cement Ratio Concretes." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64973.

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Moisture from concrete has been estimated to be responsible for over $1 billion annually from damages in floor coverings. To prevent damages, flooring manufacturers require installers to test concrete moisture levels to determine if the concrete has dried sufficiently to receive flooring or covering. Two of the main tests used in the United States to determine concrete moisture levels are moisture vapor emissions rate (MVER) tests and relative humidity (RH) tests. Changes in ambient temperature can affect the results of both RH and MVER tests. The goal of this study was to investigate the effects of ambient temperature changes on the RH of concrete, and compare the sensitivity of RH measurements to the results of MVER tests at the same ambient temperature. The RH of concrete was measured at 20%, 40%, 60%, and 80% of depth in each sample and tracked over a period of 24 days to develop drying curves at each depth, and drying profiles of each sample. The changes in concrete RH due to a change in ambient temperature were predicted using the psychrometric process and a model developed during this study. Due to size constraints on the concrete samples, ASTM 1869 had to be altered during the MVER tests. Typical RH change in the concrete samples was under 4% RH after either an increase or decrease in an ambient temperature of 5.5°C (10°F). The psychrometric process predicted that the concrete RH would change between 20% - 40% RH after the ambient temperature changed by 5.5°C. Psychrometric properties were not able to full describe the behavior of air in concrete pores so a new model was created to better predict the change in concrete RH after a change in ambient temperature. The developed model was able to predict concrete RH change within 5% error over the range of tested temperatures.
Master of Science

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6

Behrens, Christina. "Assessment of thermal properties of AAC masonry walls and panels." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1453187421&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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7

Grange, Peter James Christopher. "Investigating the Commercial Viability of Stratified Concrete Panels." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2012. http://hdl.handle.net/10092/7430.

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Buildings consume more than 30 percent of the primary energy worldwide with 65 percent of this attributed to heating ventilation and cooling. To help address this, stratified concrete panels (SCP) have been developed to provide insulation without compromising the thermal mass of concrete. SCP is created by vibrating a single concrete mix containing heavy and lightweight aggregates. Vibration causes the heavy aggregates drop to the bottom so that two distinct strata are formed; an internal structural/heavyweight layer providing thermal mass and an external lightweight layer for insulation. SCP incorporates waste products, for both financial and environmental gains, from which technical benefits also result. Stratified concrete panels have been made and tested during past research projects with results suggesting that SCP could be a competitive product in the residential construction industry, an area in which precast concrete systems have not been favoured in New Zealand. Consideration has been given to the specific rheological requirements of the concrete mix design and the hardened properties of the finished panels. This research considers the commercial viability of SCP using an industrial setting. For practicality of the setting, some materials were altered from past laboratory work to materials that are more easily sourced and better understood but with similar properties as those used previously. Several panels were cast at Stahlton precast yard in an effort to optimise the production process. Consistent results were not achieved and a range of stratification levels were produced. This showed that some capital investment is required to commercialise SCP to provide more energy for vibration such that sufficient stratification can be reliably attained. Two panels were then stood up in an exposed area with the exterior facing north to test for warping effects in a practical setting. No measurable warping occurred over this time which concurred with past work and long term readings that were taken of four year old panels. Structural, thermal and durability tests were carried out on panels with a range of stratification levels to assess the sensitivity of these properties to the level of stratification. From this it was found that the panels with better stratification had significantly better thermal properties than those with moderate to poor stratification. Generally the thermal targets for this project were not met with the total thermal resistance (R-values) not meeting current code requirements. In some cases structural properties were improved with better stratification as the structural layer was stronger through better consolidation. Delamination potential increased with stratification and with age. This requires further research to minimise this effect using fibres across the layer boundary. Porosity was increased in the structural layer in the poorly to moderately stratified panels as the structural layer was not consolidated enough due to lightweight aggregate contamination. As with any new innovation, market acceptance is largely governed by public perception. With appropriate marketing as a sustainable energy saving product, SCP has the potential to be competitive in the residential construction market with some capital investment.

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8

Hösthagen, Anders. "Thermal Crack Risk Estimation and Material Properties of Young Concrete." Licentiate thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65495.

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This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. If the stress reaches the tensile strength of the young concrete, one or several cracks will occur. The main focus of this work is how to establish a theoretical model denoted Equivalent Restraint Method model, ERM, and the correlation between ERM models and empirical experiences. A key factor in these kind of calculations is how to model the restraint from any adjacent construction part or adjoining restraining block of any type. The building of a road tunnel and a railway tunnel has been studied to collect temperature measurements and crack patterns from the first object, and temperature and thermal dilation measurements from the second object, respectively. These measurements and observed cracks were compared to the theoretical calculations to determine the level of agreement between empirical and theoretical results. Furthermore, this work describes how to obtain a set of fully tested material parameters at CompLAB (test laboratory at Luleå University of Technology, LTU) suitable to be incorporated into the calculation software used. It is of great importance that the obtained material parameters describe the thermal and mechanical properties of the young concrete accurately, in order to perform reliable crack risk calculations. Therefore, analysis was performed that show how a variation in the evaluated laboratory tests will affect the obtained parameters and what effects it has on calculated thermal stresses.

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9

Khan, Arshad A. (Arshad Ahmad). "Concrete properties and thermal stress analysis of members at early ages." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29060.

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This research program presents an experimental study on the mechanical and thermal properties of different types of concretes at very early ages, (i.e., during hydration). These properties are investigated for temperature-matched curing, sealed curing and air-dried curing. Three types of concretes are studied including normal-strength (30 MPa), medium-strength (70 MPa) and high-strength (100 MPa) concretes. About 300 cylinders and 175 flexural beams were tested to determine the early-age mechanical properties including compressive stress-strain responses, gain of compressive strength, change in elastic modulus and variation of tensile strength. Creep frames and measuring devices were built to enable the experimental determination of early-age creep, with unloaded, companion specimens giving the corresponding shrinkage strains. A temperature-matched curing bath was developed to measure the heat of hydration and to subject 15 cylinders and 12 flexural beams to temperature-matched curing. The thermal properties investigated included the heat of hydration, the thermal conductivity, the specific heat and the coefficient of thermal expansion. Expressions are proposed to predict the development of compressive strength, elastic modulus and modulus of rupture as a function of the type of concrete and the type of curing.
Sub-routines were developed for a finite element thermal analysis program "DETECT" to predict the variation of temperatures during hydration. Additional sub-routines, using the maturity concept, predicted the compressive strength, elastic modulus and tensile strength of each element, in the time domain. An experimental study was performed to observe the effect of different curing conditions and early-form stripping on the temperature and strain development in structural concrete members. Comparisons are made between the measured and predicted temperatures in large concrete columns and precast tee beams and slabs.
Sub-routines were developed to enable incremental stress analysis in the time domain to account for the rapidly changing material properties and the influence of creep. Predictions of the risk of cracking were made and compared with observations from experiments on concrete elements during hydration. Parametric analyses were carried out to determine the influence of key thermal properties, time of formwork removal, creep, and concrete strength on the thermal gradients developed and the risk of thermal cracking.

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El-Khoja, Amal M. N. "Mechanical, thermal and acoustic properties of rubberised concrete incorporating nano silica." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18351.

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Very limited research studies have been conducted to examine the behaviour of rubberised concrete (RuC) with nano silica (NS) and addressed the acoustic benefits of rubberised concrete. The current research investigates the effect of incorporating colloidal nano silica on the mechanical, thermal and acoustic properties of Rubberised concrete and compares them with normal concrete (NC). Two sizes of rubber were used RA (0.5 – 1.5 mm) and RB (1.5 – 3 mm). Fine aggregate was replaced with rubber at a ratio of 0%, 10%, 20% and 30% by volume, and NS is used as partial cement replacement by 0%, 1.5% and 3%. A constant water to cement ratio of 0.45 was used in all concrete mixes. Various properties of rubberised concrete, including the density, water absorption, the compressive strength, the flexural strength, splitting tensile strength and the drying shrinkage of samples was studied as well as thermal and acoustic properties. Experimental results of compressive strength obtained from this study together with collected comprehensive database from different sources available in the literature were compared to five existing models, namely Khatib and Bayomy- 99 model, Guneyisi-04 model, Khaloo-08 model, Youssf-16 model, and Bompa-17 model. To assess the quality of predictive models, influence of rubber content on the compressive strength is studied. An artificial neural network (ANN) models were developed to predict compressive strength of RuC using the same data used in the existing models. Three ANN sets namely ANN1, ANN2 and ANN3 with different numbers of hidden layer neurons were constructed. Comparison between the results given by the ANN2 model and the results obtained by the five existing predicted models were presented. A finite element approach is proposed for calculating the transmission loss of concrete, the displacement in the solid phase and the pressure in the fluid phase is investigated. The transmission loss of the 50mm concrete samples is calculated via the COMSOL environment, the results from the simulation show good agreement with the measured data. The results showed that, using up to 20% of rubber as fine aggregate with the addition of 3% NS can produce a higher compressive strength than the NC. Experimental results of this research indicate that incorporating nano silica into RuC mixes enhance sound absorption and thermal conductivity compared to normal concrete (NC) and rubberised concrete without nano silica. This work suggests that it is possible to design and manufacture concrete which can provide an improvement to conventional concrete in terms of the attained vibro-acoustic and thermal performance.
Libyan Ministry of Higher Education

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11

Othuman, Mydin Md Azree. "Lightweight foamed concrete (LFC) thermal and mechanical properties at elevated temperatures and its application to composite walling system." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/lightweight-foamed-concrete-lfc-thermal-and-mechanical-properties-at-elevated-temperatures-and-its-application-to-composite-walling-system(5a13ec7f-d460-4354-a296-6d1ffecff971).html.

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LFC is cementatious material integrated with mechanically entrained foam in the mortar slurry which can produce a variety of densities ranging from 400 to 1600 kg/m3. The application of LFC has been primarily as a filler material in civil engineering works. This research explores the potential of using LFC in building construction, as non-load-bearing partitions of lightweight load-bearing structural members. Experimental and analytical studies will be undertaken to develop quantification models to obtain thermal and mechanical properties of LFC at ambient and elevated temperatures. In order to develop thermal property model, LFC is treated as a porous material and the effects of radiant heat transfer within the pores are included. The thermal conductivity model results are in very good agreement with the experimental results obtained from the guarded hot plate tests and with inverse analysis of LFC slabs heated from one side. Extensive compression and bending tests at elevated temperatures were performed for LFC densities of 650 and 1000 kg/m3 to obtain the mechanical properties of unstressed LFC. The test results indicate that the porosity of LFC is mainly a function of density and changes little at different temperatures. The reduction in strength and stiffness of LFC at high temperatures can be predicted using the mechanical property models for normal weight concrete provided that the LFC is based on ordinary Portland cement. Although LFC mechanical properties are low in comparison to normal weight concrete, LFC may be used as partition or light load-bearing walls in a low rise residential construction. To confirm this, structural tests were performed on a composite walling system consisting of two outer skins of profiled thin-walled steel sheeting with LFC core under axial compression, for steel sheeting thicknesses of 0.4mm and 0.8mm correspondingly. Using these test results, analytical models are developed to calculate the maximum load-bearing capacity of the composite walling, taking into consideration the local buckling effect of the steel sheeting and profiled shape of the LFC core. The results of a preliminary feasibility study indicate that LFC can achieve very good thermal insulation performance for fire resistance. A single layer of 650 kg/m3 density LFC panel of about 21 mm would be able to attain 30 minutes of standard fire resistance rating, which is comparable to gypsum plasterboard. The results of a feasibility study on structural performance of a composite walling system indicates that the proposed panel system, using 100mm LFC core and 0.4mm steel sheeting, has sufficient load carrying capacity to be used in low-rise residential construction up to four-storeys.

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12

Bozkurt, Emrah Tanoğlu Metin. "Mechanical and thermal properties of non-crimp glass fiber reinforced composites with silicate nanoparticule modified epoxy matrix/." [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/makinamuh/T000517.pdf.

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Thesis (Master)--İzmir Institute of Technology, İzmir, 2006
Keywords: polymer composites, Nanoparticles, glass fiber, mechanical properties, thermal properties. Includes bibliographical references (leaves 75-79).

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13

Chang, Lei. "Experimental Data on Fire-Resistance Behavior of Reinforced Concrete Structures with Example Calculations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3003/.

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This thesis selects concrete, steel and their relation as research subjects, mainly commentary and discusses the property changes of steel and concrete materials under and after high temperature.The differences and comparisons of reasearch methods and ways between different researchers and different papers,particularly for chinese researches and chinese papers,and partly for comparison between chinese papers methods and Euro-Amercian papers methods about Fire Resistance Behavior of Reinforced Concrete will be summarized and analyzed.The researches on fire-resistance behavior of reinforced concrete become more and more important all over the world. And I would find differences between Chinese researches results, between Chinese researches results and other countries researches results.

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14

SANTOS, WILSON N. dos. "Contribuicao ao estudo da condutividade termica do material ceramico concreto refratario utilizando a tecnica de fio quente com ajustes por regressao nao linear." reponame:Repositório Institucional do IPEN, 1988. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9901.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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15

Faneca, Llesera Gerard. "Desarrollo de hormigones conductores con adición de fibras de carbono recicladas." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669280.

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Inside the studies of intelligent materials and considering concrete as one of the most building material used, getting new functionalities to him, would provide new uses and applications to the usual structural or facing purposes. Factor that would allow the material to evolve while maintaining its validity in new challenges that arise in infrastructure areas, such as the smart city, mobility, self-sensing of structures and other possible applications still to be developed. With this objective marked and introducing factors such as sustainability and medium-term industrialization, this thesis focuses on the use of recycled carbon fibers from products or processes, added to concrete, in order to modify its electrical properties and transform it, from one insulating material, to another with conductive properties. Therefore, based on previous studies, two concrete matrix are characterized with particular differences in the size of their aggregates. Both two matrix receive the addition of different types of carbon fiber recycled in different percentages. In a first phase, the study focuses on the characterization of the different basic properties of concrete, such as structural capacity and workability in fresh condition. The determination of electrical properties is added and established specific test typologies to evaluate, compare and analyze the effect of the different phases present in the material, on the electrical conductivity of all combinations of proposed mixes. Subsequently, focusing on the combinations of matrix, type and quantity of fiber with better conductive properties, deeper electrical characterization is done, contrasting it with associated functionalities such as the piezoelectric effect and the Joule effect. Functionalities that govern the self-sensing and self-heating of concrete applications such as the control of deformations of structures or pavements with de-icing effect. Finally, the material developed in a full-scale pilot test is applied, in which the functionality of self-heating is tested in an element of urban furniture by the company ESCOFET 1886 S.A., which has participated in the realization of this doctoral thesis inside the framework of the Industrial Doctoral Program of the Generalitat de Catalunya.
Dentro del ámbito de los materiales inteligentes y considerando el hormigón como uno de los principales materiales de la construcción, conseguir dotarle de nuevas funcionalidades le proporcionaría nuevos usos y aplicaciones a las meramente estructurales o de revestimiento habituales. Factor que permitiría evolucionar el material manteniendo su vigencia ante nuevos retos que se plantean en ámbitos de las infraestructuras, como la ciudad inteligente, movilidad, sensorización de estructuras y otras aplicaciones posibles todavía por desarrollar. Con este objetivo marcado e introduciendo factores como la sostenibilidad y una industrialización a medio plazo, esta tesis se centra en la utilización de fibras de carbono recicladas de productos o procesos, adicionadas al hormigón, con el fin de modificar sus propiedades eléctricas y transformarlo de un material aislante a otro con propiedades conductivas. Por ello y basándose en estudios previos, se caracterizan dos matrices de hormigón con marcadas diferencias en lo que refiere al tamaño de sus agregados, que reciben la adición de diferentes tipos de fibra de carbono recicladas en distintos porcentajes. En una primera fase, el estudio se centra en la caracterización de las diferentes propiedades básicas del hormigón, como la capacidad estructural o trabajabilidad en estado fresco, a la que se añade la determinación de las propiedades eléctricas a la vez que se establecen tipologías de ensayo específicos con los que poder evaluar, comparar y analizar el efecto de las diferentes fases presentes en el material en la conductividad eléctrica de todas las combinaciones de dosificaciones propuestas. Posteriormente, focalizándose en las combinaciones de matriz, tipo y cantidad de fibra con mejores propiedades conductivas, se profundiza en la caracterización eléctrica, contrastándola con funcionalidades asociadas como el efecto piezoeléctrico y el efecto Joule, funcionalidades que gobiernan la sensorización del hormigón y autocalentamiento en aplicaciones como el control de deformaciones de estructuras o pavimentos con efecto deshielo respectivamente. Finalmente se aplica el material desarrollado en una prueba piloto a escala real, en la que se testean la funcionalidad de autocalentamiento en un elemento de mobiliario urbano de la empresa ESCOFET 1886 S.A., que ha participado en la realización de esta tesis doctoral en el marco del Programa de Doctorado Industrial de la Generalitat de Catalunya

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Albuquerque, Albéria Cavalcanti de. "Estudo das propriedades de concreto massa com adição de partículas de borracha de pneu." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16484.

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O aproveitamento de partículas de pneus inservíveis no concreto tem sido objeto de estudo de diversos pesquisadores, pois se justifica como uma alternativa atraente de disposição desses resíduos ao mesmo tempo em que resulta em modificações das propriedades do concreto que podem ser benéficas para certas aplicações, que requerem características específicas, tais como maior capacidade de deformação e comportamento à fratura menos frágil do que o concreto convencional. Essas características do concreto com borracha de pneu (CBP) podem ser interessantes para a redução do risco de fissuração de concretos submetidos a variações volumétricas, caso típico dos concretos massa. Nesta pesquisa se buscou averiguar como a adição de partículas de pneu afeta as propriedades mecânicas, térmicas e viscoelásticas do concreto massa, com o intuito de verificar se era possível obter um compósito menos suscetível aos riscos de fissuração devido a efeitos térmicos. As dosagens de concreto massa com borracha de pneu estudadas foram analisadas em função do teor, da granulometria e do tratamento superficial aplicado às partículas de borracha de pneu. O programa experimental foi desenvolvido em três etapas. A primeira delas envolveu uma ampla faixa de teores de borracha, sendo realizados ensaios básicos para identificar a eficácia dos tratamentos superficiais em proporcionar uma boa interface borracha/matriz do concreto e o maior teor de substituição das partículas de borracha sem prejuízo das propriedades mecânicas. Nessa etapa foram também selecionadas amostras para análise microestrutural por microscopia eletrônica de varredura, a fim de correlacionar a qualidade da interface borracha/matriz do concreto com as características mecânicas. Na segunda etapa foram selecionados os parâmetros que resultaram em melhor desempenho dentre as variáveis analisadas na primeira etapa e buscouse avaliar o efeito da adição de partículas de pneu nas propriedades referentes à tenacidade e à permeabilidade do concreto. Para o desenvolvimento da terceira etapa do estudo foram selecionadas duas composições mais promissoras dentre aquelas utilizadas na primeira e na segunda etapas, a fim de analisar o efeito da borracha de pneu nas propriedades térmicas, elásticas e viscoelásticas do concreto, bem como o comportamento termomecânico. Adicionalmente, algumas amostras foram submetidas a ensaios com vistas à avaliação de características referentes à durabilidade. Os resultados indicaram que o máximo aproveitamento da borracha de pneu no concreto, sem prejuízo considerável das propriedades mecânicas, ocorre para o teor de 10% de partículas de borracha de 1,5mm e 4,8mm em substituição parcial do volume de areia. Teores mais elevados e partículas de menor dimensão levaram a uma contínua redução das propriedades mecânicas e aumento do teor de ar aprisionado. Não houve diferença significativa de propriedades nem na microestrutura das amostras contendo partículas com e sem tratamento superficial. As análises termomecânicas indicaram que o uso de concretos com borracha de pneu pode ser uma alternativa eficiente para minimizar o risco de fissuras de origem térmica, quando comparados a um concreto convencional. Com base nos resultados obtidos até a idade de 2 anos, verifica-se que o consumo de 29 kg/m3 de borracha de pneu no concreto não prejudica as características de durabilidade do material.
The use of waste tire rubber particles in concrete has been studied by several researchers, because it constitute both an attractive alternative for the final disposition of these residues and offers a possibility to modify certain concrete properties that might contribute for a better performance in certain applications that require specific characteristics, such as increased deformation capacity and more ductile behavior than conventional concrete. These characteristics of rubberized concretes might be interesting because they reduce the risk of cracking when concrete is subjected to volumetric changes, as occurs with mass concretes. In this research, it was studied how the introduction of rubber particles would affect the mechanical, viscoelastic and thermal properties of mass concretes, with the aim to check if it is possible to obtain a composite less susceptible to cracking due to thermal effects. The mixtures were analyzed based on the following features: rubber content, granulometry and surface treatment applied to the tire rubber particles. The experimental program was performed in three stages. The first one involved a wide range of mixtures, with varying rubber contents. At this stage, basic tests were carried out in order to identify how effective surface treatments were in generating a good tire rubber/matrix interface as well as how much high tire rubber contents would impact the mechanical properties of the concrete. Samples were selected for microanalysis through scanning electron microscopy to correlate the quality of the rubber/matrix interface with mechanical characteristics. In the second stage, the mixtures that resulted in the best performance in the first stage were further studied. The effects of the addition of tire rubber particles on the properties related to tenacity and permeability of concrete were evaluated. During the third stage, the best two mixtures used in the first and second stages were selected in order to analyze the effect of the addition of rubber particles in the thermal, elastic and viscoelastic properties of concrete, as well as in the thermo mechanical behavior of structures made with this material. Additionally, some samples were subjected to tests for the assessment of features related to the durability of concrete. The results indicated that the best use of tire rubber on concrete, without reducing the mechanical properties, occurs for a 10% content of rubber particles of 1.5mm and 4.8mm, used in partial replacement of the river sand. Higher contents and smaller particles led to greater reductions of the mechanical properties and an increase in the trapped air content. There was no significant difference either in the microstructure or in the properties of the samples containing particles with and without surface treatment. The thermo mechanical analysis indicated that the use of concrete with tire rubber can be an efficient alternative to minimize the risk of cracking due to thermal effects, compared with a conventional concrete. Based on the results obtained until the age of 2 years, the consumption of 29 kg/m3 of tire rubber on concrete did not seem to affect the durability characteristics of the material.

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Pecháčková, Kateřina. "Tepelné vlastnosti vysokohodnotného betonu s vláknovou výztuží." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-377314.

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Анотація:

This diploma thesis is focused on the study of the thermal properties of high-performance fiber reinforced concrete HPFRC. The composites are based on a combination of steel and polymeric fibers. Typical properties of these materials include high mechanical strength, water resistence and salt penetration. HPFRCs are mainly used in the construction industry to build tall buildings. The differential transient method was used to study thermophysical variables. The theoretical part of the thesis described the types of concrete, their production, and their properties. Furthermore, thermophysical quantities and methods of their determination (stationary and transient methods, thermal analysis) are defined in the thesis. The aim of the thesis was to determine thermal properties, namely thermal conductivity and specific heat capacity. The results of the thesis can reveal changes in the composition of studied materials as well as critical temperatures for damaging the materials.

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Angelin, Andressa Fernanda 1989. "Concreto leve estrutural : desempenhos físicos, térmicos, mecânicos e microestruturais." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267702.

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Анотація:

Orientadores: Luísa Andréia Gachet Barbosa, Rosa Cristina Cecche Lintz
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia
Made available in DSpace on 2018-08-24T22:32:15Z (GMT). No. of bitstreams: 1 Angelin_AndressaFernanda_M.pdf: 3316470 bytes, checksum: e0844bd6dbe8b1d62eefa5eec0498b83 (MD5) Previous issue date: 2014
Resumo: A busca por materiais alternativos, de baixa massa específica, que possua redução na transferência de propagação de calor, associado à facilidade de manuseio e aplicação em concretos estruturais e estruturas de vedação, representa grande desafio na formulação e conhecimento do desempenho dos concretos leves. O concreto leve possui tecnologia pouco difundida em nível nacional e surge no cenário atual como um material inovador e alternativo ao concreto convencional. Frente ao exposto, este trabalho estudou concretos leves estruturais elaborados com duas graduações distintas de argila expandida e, com a finalidade de promover à manutenção das propriedades mecânicas, adicionou-se aditivo superplastificante e sílica ativa. Desenvolveu-se cinco traços distintos, que apresentaram reologia adequada, sem apresentar fenômenos de segregação e exsudação. Estudou-se algumas propriedades físicas, como índice e perda de consistência, absorção de água e massa específica do estado fresco e endurecido, os quais apresentaram uma média de 2000 kg/m3, classificando os concretos, de acordo com o ACI 213R-03 (2003), como leves. As principais propriedades mecânicas analisadas foram, resistência à compressão, apresentando, em média, 40 MPa, valor acima do mínimo prescrito pela ABNT NBR 6118:2007, para concretos estruturais, além da resistência à tração e módulo de elasticidade, as quais serviram como fundamentação na qualificação dos concretos leves estruturais, visando às exigências técnicas nacionais e internacionais para sua classificação e uso. Também foram realizados ensaios de condutividade térmica, por meio do método da placa quente protegida ("Hot Plate"), os quais apresentaram bons resultados, mostrando-se adequados no quesito desempenho térmico, de acordo com a revisão bibliográfica, bem como, com a norma nacional de desempenho térmico (ABNT NBR 15220:2005). Foram obtidas informações microestruturais sobre a zona de transição entre os agregados, convencionais e leves, e sua matriz de cimento. Foram realizadas comparações entre a massa específica seca e a resistência à compressão, assim como, comparações entre a massa específica seca e o módulo de elasticidade, sendo que tais resultados comprovam a possibilidade da utilização do concreto leve em elementos estruturais. Sugere-se, então, utilizar este concreto em painéis de vedação, pois associa-se a baixa massa específica, o conforto térmico e a resistência mecânica
Abstract: The search for alternative materials, low density, having reduced transfer of heat propagation, combined with ease of handling and application in structural concrete and seal structures, constituting a major challenge in the design and understanding of the performance of lightweight concrete. The lightweight concrete technology has little known at the national level and in the current scenario emerges as an innovative and alternative material to conventional concrete. Based on these, this paper studied structural lightweight concrete made with two different grades of expanded clay, and with the purpose of promoting the maintenance of the mechanical properties was added superplasticizer and silica fume. Developed five distinct traits, which showed adequate rheology, without presenting phenomena of segregation and oozing. We studied some physical properties, such as loss of consistency index, water absorption and density of fresh and hardened, which had an average 2000 kg/m3, classifying the concrete according to ACI 213R-03 (2003), as light. The main mechanical properties were analyzed, compressive strength, with an average of 40 MPa, above the minimum prescribed by ABNT NBR 6118:2007, structural concrete, beyond the tensile strength and modulus of elasticity, which served as the basis the qualification of structural lightweight concrete, aimed at national and international technical requirements for classification and use. Thermal conductivity tests were also carried out by means of the hot plate protected ("Hot Plate") method, which showed excellent results, proving to be adequate thermal performance in the category, according to the literature review, as well as with the national standard for thermal performance (ABNT NBR 15220:2005). Microstructural information on the transition zone between aggregates, conventional and light, and its cement matrix were obtained. Comparisons between dry density and compressive strength as well as comparisons between the dry density and modulus of elasticity were performed, and these results show the possibility of using lightweight concrete in structural elements. Then it is suggested to use this concrete fence panels, as is associated with low density, thermal comfort and strength
Mestrado
Tecnologia e Inovação
Mestra em Tecnologia

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Nguyen, Le Hung. "Béton de structure à propriétés d'isolation thermique améliorées : approche expérimentale et modélisation numérique." Phd thesis, Université de Cergy Pontoise, 2013. http://tel.archives-ouvertes.fr/tel-00931711.

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Анотація:

Dans un bâtiment, les déperditions thermiques proviennent de diverses parties opaques (mur, toit et plancher) qui peuvent contenir du béton. Il est donc intéressant d'envisager des formulations de béton de structure avec des propriétés d'isolation thermique améliorées. L'utilisation de granulats légers, qui possèdent de bonnes propriétés thermiques grâce à leur structure poreuse, peut être une solution pour améliorer la capacité d'isolation des éléments en béton. Cette technique d'isolation répartie peut permettre d'éviter des dispositifs constructifs lourds tout en répondant aux exigences de la RT 2012. La présente étude a pour objectif d'optimiser le couple performance mécanique - capacité isolante des bétons de granulats légers. Elle repose sur une double approche expérimentale et numérique.Les bétons de granulats légers ciblés ont une masse volumique inférieure à 1500 kg/m3 et une résistance en compression supérieure à 25 MPa. L'influence de la nature des granulats légers, du taux de substitution du sable alluvionnaire par du sable léger, du rapport E/C et de l'ajout de fumée de silice sur les performances mécaniques et thermiques des bétons est étudiée afin de proposer des formulations adéquates pour une large gamme d'usage structurel. Le module d'Young, la résistance en compression, la conductivité thermique et la diffusivité sont mesurées sur 25 formulations de bétons de granulats légers. Le comportement thermique de ces différents bétons en fonction de facteurs climatiques, comme la température et le degré d'humidité est aussi examiné afin d'optimiser leurs propriétés d'isolation thermique. L'ensemble des résultats expérimentaux permet une meilleure compréhension de la relation entre la formulation des bétons de granulats légers et leur rapport performance mécanique / pouvoir isolant. En s'appuyant sur certaines mesures expérimentales, des modélisations numériques reposant sur des techniques d'homogénéisation permettent d'identifier des propriétés thermiques (conductivité thermique, chaleur spécifique) et mécaniques (module d'Young, résistance à la rupture) des granulats légers (gravillons et sables) difficilement mesurables expérimentalement. Connaissant les propriétés thermiques et mécaniques des différents constituants, des modélisations prédictives des comportements macroscopiques des bétons légers sont développées à partir de schémas d'homogénéisation pour des matériaux multi-phases polydisperses. Les outils développés sont comparés et validés par confrontation aux mesures expérimentales pour les différentes familles de bétons de granulats légers étudiés. Ils permettront par la suite d'alléger les coûts et délais des campagnes expérimentales de mise au point des formulations. La modélisation, sur une année, des transferts thermiques à travers une enveloppe de bâtiment en béton de granulats légers permet de quantifier l'amélioration des performances thermiques des bétons de granulats légers par rapport à un béton classique.

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Jurka, František. "Bytový dům, Brno - Židenice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227838.

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Subject of this diploma thesis is desing dokumentation of apartment house. Documentation contains all requisites according to valid regulations. House is designed as detached basement house with one underground floor and five aboveground floors. Object is based on reinforced concrete foundation pads. House is roofed with a flat roof. House contains 18 dwelling units with balconies or terraces. In object is solved parking in underground floor. Vertical load-bearing structure is made of clay blocks. Floors are made of cast-in-place reinforced concrete. Underground floor load-bearing structure is reinforced concrete frame. House is insulated with contact thermal insulation. Mechanical resistence and stability, health protection, healthy live conditions and enviroment, fire security, safety in use of building, energy savings and thermal protection is ensured.

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Xing, Zhi. "Influence de la nature minéralogique des granulats sur leur comportement et celui du béton à haute température." Phd thesis, Université de Cergy Pontoise, 2011. http://tel.archives-ouvertes.fr/tel-00624785.

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Анотація:

Le béton est un matériau de construction omniprésent dans les ouvrages de génie civil en raison de sa facilité de mise en oeuvre et son faible coût économique. Suite à des incendies de tunnels ou de bâtiments, les structures en béton peuvent présenter d'importantes dégradations. Afin de pouvoir concevoir des ouvrages plus sûrs il s'avère nécessaire de comprendre les phénomènes physiques à l'origine des désordres dans les structures en béton portées à température élevée. Les travaux de recherche de cette thèse permettent de compléter les connaissances déjà acquises sur le comportement du béton à température élevée en mettant l'accent sur le comportement des granulats, de l'interaction pâte/granulats et béton/roche. Ce travail de recherche basé sur une approche expérimentale analyse l'influence de différentes natures de granulats sur le comportement thermo-hydro-mécanique du béton soumis à une température élevée. Cette étude est construite en trois parties : l'étude du comportement des granulats soumis à température élevée, l'étude du comportement du béton avec les granulats testés précédemment et enfin l'étude d'un échantillon bicouche simulant la relation béton/roche dans un tunnel en incendie. Dans la première partie, trois granulats (calcaire concassé, silico-calcaire semi-concassé de Seine et siliceux roulé) subissent des cycles de chauffage/refroidissement à une vitesse de 1°C/min à 150°C, 300°C, 450°C, 550°C, 600°C et 750°C. Pour une même nature de granulat siliceux, le silex présente une instabilité thermique se traduisant par un éclatement à partir de 300°C alors que le quartzite présente une bonne résistance thermique. La cristallinité et la microstructure du quartz jouent un rôle important dans leur stabilité thermique. La teneur en eau initiale présente aussi une importance sur le comportement thermique du silex. Le granulat calcaire présente aussi une instabilité à cause des phénomènes de décarbonatation/hydratation mais seulement pour le cycle de chauffage/refroidissement à 750°C. Les évolutions physico-chimiques, minéralogiques et microstructurales de ces granulats soumis à une température élevée sont ensuite analysées pour bien comprendre le processus d'instabilité. L'évolution des endommagements du silex est décrite par une série d'observations de la fissuration de l'échelle macroscopique à nanoscopique. La deuxième partie de l'étude expérimentale est consacrée aux bétons réalisés avec les trois granulats analysés précédemment. Pour chaque type de granulat, deux rapports E/C de 0.6 et 0.3 pour les bétons sont étudiés. Ces bétons subissent les mêmes cycles de chauffage/refroidissement que les granulats. Nous déterminons l'évolution de la fissuration, des propriétés thermiques, physiques et mécaniques des bétons en fonction des températures subies. Le comportement mécanique résiduel du béton varie selon la nature des granulats et l'influence du granulat dépend aussi de la compacité de la pâte cimentaire. La partie relative à la simulation d'un incendie dans un tunnel avec un bicouche roche/béton fabriqué au laboratoire permet d'analyser le comportement du béton et de la roche en s'intéressant aux transferts de chaleur dans les 2 matériaux au cours de l'exposition à une température élevée. Mots clés : béton, granulat siliceux et calcaire, microstructure, propriétés mécaniques, propriétés thermiques, haute température.

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RAHELIARILALAO-RANAIVO, RABEHAJA BIENVENUE. "Etude des caracteristiques thermiques et mecaniques de betons de pouzzolane." Paris 7, 1986. http://www.theses.fr/1986PA077220.

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Анотація:

Etude des pouzzolanes naturelles de l'ile de la reunion, comme composants de base de beton alleges, en soulignant les avantages thermiques. Proprietes chimiques, mineralogiques et physiques des granulats de pouzzolane. Adaptation d'une modelisation thermique pour les corps poreux, avec nouvelle methode de determination de la diffusivite. Description des appareillages de mesure de la conductivite et diffusivite thermiques, et presentation des resultat

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Larget, Mathilde. "Contribution à l’évaluation de la dégradation du béton : thermographie infrarouge et couplage de techniques." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14318/document.

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Анотація:

Ces travaux traitent de l'utilisation de la thermographie infrarouge dans le cadre du contrôle non destructif des ouvrages de génie civil.Une première partie, traite de l’étude des paramètres influençant la mesure in situ, de la capacité de la technique à détecter la variation de propriétés intrinsèques au matériau, et de la détection de délaminations. Les résultats présentés sont issus de mesures expérimentales appuyées par une approche numérique aux éléments finis. Dans un premier temps, une étude sur la capacité de la thermographie infrarouge à détecter des variations de porosité ou de teneur en eau a été réalisée. Dans un second temps, des travaux sont menés sur la détermination des seuils de détection des délaminations en fonction des conditions d’exposition. Ils ont montré un seuil de détection correspondant à un rapport de 2, entre l’extension latérale du défaut et sa profondeur, pour un ensoleillement direct, et à un rapport de 3,3 pour un ouvrage soumis uniquement aux variations de température de l’air. La réalisation d’un suivi temporel combiné à l’étude de l’évolution des gradients temporels de température permet d’améliorer ces seuils de détection. Enfin, une étude originale sur le pontage présent au niveau des délaminations, a montré la prédominance de l’influence de celui‐ci sur la profondeur des délaminations.Une deuxième partie porte sur les travaux réalisés dans le cadre du projet ANR‐SENSO. Ils traitent de la combinaison des résultats issus de différentes techniques de CND dans le cadre plus large de l'amélioration des diagnostics pour la gestion du patrimoine
This thesis focuses on the use of infrared thermography as a tool for non destructive testing ofbuildings. Mainly, the application is on civil engineering projects.The first part includes identifying the parameters that can affect this in situ technique. Thisparticularly deals with the infrared thermography capacity to detect intrinsic property variations, anddelamination detection. Combination of experiments on concrete slabs and numerical simulationsare used. In a first step, a study on the capacity of thermography to detect porosity and watercontent variation was conducted. In a second step a study on the thresholds for detectingdelaminations based on exposure conditions is carried out. As an outcome, the threshold that hasbeen detected corresponds to a ratio of 2 between the lateral extension of the defect and its depthto direct sunlight; while a ratio of 3,3 if it is exposed to air temperature variations. This studysuggests that a time monitoring combined with the study of the evolution of temporal temperaturegradients can improve the detection limits. Finally, an original study showed the predominance ofthe influence of bridging on the depth of delamination.The second part tackles the works carried out during the ANR project SENSO. Results fromdifferent non destructive tools were coupled for the purpose of improving diagnosis in the assetmanagement

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Башинська, Ольга Юріївна, та Olha Bashynska. "Створення розрахункових моделей будівельних конструкцій при врахуванні реологічних властивостей залізобетону". Thesis, Національний авіаційний університет, 2019. http://er.nau.edu.ua/handle/NAU/40283.

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Анотація:

Дисертація присвячена розробці методики розрахунку залізобетонних конструкцій на основі подвійного степеневого закону, із врахуванням впливу фізичної нелінійності та реологічних властивостей бетону, а також, із врахуванням впливу зміни температури оточуючого середовища та при розрахунку на вогнестійкість. Розроблена універсальна методика для чисельного розрахунку залізобетонних елементів конструкцій, що дозволяє врахувати вплив зміни температури в перерізі елементів на зниження механічних та деформаційних властивостей матеріалів. Також, розроблено алгоритм визначення деформацій конструкції із врахуванням виникнення деформацій повзучості на основі подвійного степеневого закону. Вдосконалено алгоритм визначення функції повзучості при врахуванні впливу зміни температури оточуючого середовища. Отримані рівняння і розроблена методика розрахунку плит перекриття при впливі температурних факторів, та із врахуванням в’язкопружнопластичності бетону. Набула подальшого розвитку математична модель, що дозволяє врахувати зміну температури навколишнього середовища та її вплив на розвиток нелінійних деформацій, із врахуванням зниження міцнісних та деформаційних характеристик матеріалу. Запропоновану методику можна використовувати при проектуванні будівель та споруд, в яких можуть проявлятися деформації повзучості. Виконані чисельні експерименти дозволяють визначити небезпечні фактори, що характеризують можливу зміну умов експлуатації будівлі (збільшення пластичних деформацій або високотемпературні впливи тощо). Наведені алгоритми розрахунку конструкції можуть бути використані при повторному перерахунку будівель та споруд, що зазнали вогневого впливу. Результати дослідження можна використовувати при удосконаленні стандартів у рамках забезпечення конструктивної безпеки будівель та споруд у випадку впливу високих або підвищених температур.
Диссертация посвящена разработке методики расчета железобетонных конструкций на основе двойного степенного закона, с учетом влияния физической нелинейности и реологических свойств бетона, а также с учетом влияния изменения температуры окружающей среды и при расчете на огнестойкость. Разработана универсальная методика для численного расчета железобетонных элементов конструкций позволяет учесть влияние изменения температуры в сечении элементов на снижение механических и деформационных свойств. Также, разработан алгоритм определения деформаций конструкции с учетом возникновения деформаций ползучести на основе двойного степенного закона. Усовершенствован алгоритм определения функции ползучести при учете влияния изменения температуры окружающей среды. Полученные уравнения и разработана методика расчета плит перекрытия при воздействии температурных факторов, и с учетом вязкоупругопластичности бетона. Получила дальнейшее развитие математическая модель, позволяющая учесть изменение температуры окружающей среды и ее влияние на развитие нелинейных деформаций, с учетом снижения прочностных и деформационных характеристик материала. Предложенную методику можно использовать при проектировании зданий и сооружений, в которых могут проявляться деформации ползучести. Выполнены многочисленные эксперименты позволяют определить опасные факторы, характеризующие возможную смену условий эксплуатации здания (увеличение пластических деформаций или высокотемпературные воздействия и т.д.). Приведенные алгоритмы расчета конструкции могут быть использованы при повторном пересчете зданий и сооружений, подвергшихся огневому воздействию. Результаты исследования можно использовать при усовершенствовании стандартов в рамках обеспечения конструктивной безопасности зданий и сооружений в случае воздействия высоких или повышенных температур.
The consideration of rheological properties of concrete is one of the most important stages in ensuring the long-term and safe operation of buildings and structures. Rheological properties include shrinkage, swelling, creep and relaxation. Within the dissertation, the phenomenon of creep is investigated. Creep is temperate deformation of the body under the action of constant load. The property of creep is characterized for a lot of materials. Real buildings are often subjected to variable loads that cause instant elastic and plastic deformation, as well as creep. In order to study the motion of the material in creep, ordinary devices of a continuous medium mechanical are used. That is, they are introduced the tensor of voltage, deformation and rapid deformation. In the general case, the displacement of the points of the body may be significant in comparison with its original dimensions. In this case, its deformation must be described by means of the final deformation tensor, and at the deformed body surface must also be given by the corresponding boundary conditions. An important property of concrete is that when the temperature of the surrounding environment increases, the modulus of elasticity of the material decreases. It’s possible to take into account the decrease in the elasticity modulus by using the lowering coefficients. But all construction documents say that full calculation and analysis of structures should be done not only with taking into account the lowering coefficients, but also the coefficients that will take into account the effect of creep, depending on the temperature change. In the work, the calculation methodology for reinforced concrete structures is represented. The methodology is developed on the basis of a double power law, taking into account the influence of high temperatures and the calculation on fire resistance, as well as taking into account the influence of physical nonlinearity and rheological properties of concrete.

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Bahrar, Myriam. "Contribution au développement et à l’analyse d’une enveloppe de bâtiment multifonctionnelle dans le cadre de l’optimisation du confort dans l’habitat." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEE001/document.

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Анотація:

Le secteur du bâtiment recèle un fort potentiel d’amélioration de l'efficacité énergétique et de réduction de l’empreinte écologique. Dans cette optique, l’enveloppe du bâtiment joue un rôle important pour relever le défi de la transition énergétique. En effet, une bonne conception de l’enveloppe contribue efficacement à réduire la consommation d’énergie tout en réduisant les émissions de CO2 associés. Cela s’accompagne notamment d’une démarche de développement de nouveaux matériaux et principes constructifs. Ce projet de thèse s’inscrit dans ce cadre en proposant un nouveau matériau composite, qui porte sur l’association de deux matériaux innovant : composite textile mortier (TRC) et matériaux à changement de phase (MCPs). L’objectif de cette combinaison est de contribuer au développement d’éléments de façades multifonctionnelles permettant d’allier performances énergétiques, mécaniques et environnementales. Le but de notre étude est de caractériser en premier lieu, les propriétés mécaniques et thermiques de ces composites puis, d’évaluer l’impact des MCPs sur le confort thermique intérieur pour différentes configurations. Pour atteindre ces objectifs, nous avons adopté une démarche expérimentale et numérique multi échelle. Une campagne expérimentale à l’échelle du laboratoire et in-situ a été menée. En parallèle, nous avons développé un modèle numérique de paroi multicouche, couplé à un modèle de bâtiment. Enfin, nous avons exploité ce couplage pour réaliser une optimisation multicritère à base d’algorithmes génétiques
The building sector has a great potential to improve energy efficiency and reduce the greenhouse gas emissions. Improvements to the building envelope and Innovations in building materials have the potential to achieve sustainability within the built environment. This PhD thesis focuses on the development of multifunctional façade elements in order to optimize the building energy consumption while maintaining an optimal indoor human thermal comfort. The proposed solution consist of using passive storage by means of phase change materials associated with alternative construction materials such as textile reinforced concrete (TRC). The aim of the study is to characterize mechanical and thermal properties of TRC composites and to evaluate the effect of PCMs on indoor thermal comfort. To meet these objectives, experimental devices have been set up for the characterization (at the component scale and in situ) of the mechanical and thermal behaviour of different TRC panels. In parallel, we have developed a numerical model for the prediction of wall temperature profiles. Finally, a multi-objective optimization of the façade elements is carried out using genetic algorithms to determine the better combinations able to combine the energy performance with the mechanical performance

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Elalaoui, Oussama. "Optimisation de la formulation et de la tenue aux hautes températures d’un béton à base d’époxyde." Thesis, Cergy-Pontoise, 2012. http://www.theses.fr/2012CERG0577.

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Анотація:

La durabilité des matériaux employés en génie civil est remise en question par le vieillissement physico-chimique de ces matériaux pouvant engendrer des dégradations significatives qui peuvent mettre en péril la stabilité des structures du génie civil. Pour pallier à certains inconvénients des bétons hydrauliques, l'utilisation des matériaux composites à l'instar des bétons de résine, qui possèdent des qualités remarquables par rapport aux matériaux de construction conventionnels, s'avère très intéressant.À l'heure actuelle, les freins majeurs quant aux développements des bétons résines sont d'une part le coût de la résine dont le taux varie, selon l'application industrielle, de 5% à 25% et d'autre part leurs comportements aux températures élevées et au feu puisque les liants dans ces bétons sont des substances organiques qui résistent beaucoup moins à la chaleur que les matières inorganiques. L'objectif de l'étude est de favoriser le développement des bétons résines par la diminution du taux de la résine en optimisant les constituants du béton et l'amélioration de leurs ténues aux températures élevées par l'ajout des additions tout en assurant des performances mécaniques raisonnables. L'optimisation de la formulation du béton est menée sur deux étapes ; la première vise à optimiser le squelette granulaire (sable 0/4 et Gravier 4/10, silico-calcaires) expérimentalement en confrontant les résultats à ceux issus du modèle d'empilement compressible. La deuxième étape vise à optimiser la fraction massique du liant époxydique (6%, 9%, 13% et 16%) sur la base des essais de caractérisation mécaniques et physiques. Le deuxième objectif de l'étude a était menée par l'ajout des ignifugeants appartenant à deux familles différentes c'est-à-dire les hydroxydes de métal et les produits phosphorés inorganiques. Les propriétés physiques, thermiques et mécaniques des bétons additionnées et témoins, avant et après exposition à un cycle de chauffage-refroidissement de la température ambiante à une température de consigne de 100°C, 150°C, 200°C, 225°C et 250 °C avec une vitesse de montée fixée à 0.5°C/min, ont été évaluées par les techniques de caractérisation usuelles en plus des essais d'analyses chimiques et thermiques.Cette étude aboutit à la formulation d'un béton optimal en terme de composition et à évaluer l'effet de l'addition des ignifugeants surtout sur les propriétés thermiques et mécaniques.Mots clés : béton de résine, optimisation, température élevée, ignifugeants, propriétés mécaniques, propriétés physiques, propriétés thermiques
The material used in civil engineering applications must be re-evaluated because of their physicochemical ageing which can generate significant damages and hence put the stability of civil engineering structures in danger.The replacement of the hydraulic concrete by composite materials as the polymer concrete which offer higher properties compared to conventional construction materials seems to be very interesting. At the present time, the major restrain for the development of polymer concrete are on one hand the cost of the polymer whose ratio varies according to the industrial applications between 5% and 25%, and on the other hand their behaviour when exposed to high temperatures or fire since the resin acting as binder in these polymer concretes are organic substances which are more sensitive to heat than the inorganic matters as cement.The aim of this study was to help the development of polymer concrete by optimizing the formulation and improving their behaviour when exposed the high temperatures by incorporating additions while keeping acceptable mechanical performances.The optimisation of the formulation is done in two steps; the first step consists of optimising the aggregates content (Natural River sands 0/4 mm and crushed gravels 4/10 mm). Experimental results are compared to those given by means Compressible Packing Model. The second step consists of optimizing the amount of polymer (6%, 9%, 13% et 16%) based on mechanical and physical tests.The second aim of this work was fulfilled by the incorporation of two flame retardants belonging to metal hydroxide and phosphorous components types. Physical, thermal and mechanical properties of concretes with or without flame retardant, before and after heating-cooling cycle from ambient temperature to exposure temperature of 100°C, 150°C, 200°C, 225°C et 250 °C with a rate of 0.5°C/min, are evaluated by common characterisation tests besides chemical and thermal ones. This study has leading to obtaining an optimum polymer concrete and evaluates the effect of flame retardant particularly on the thermal and mechanical properties.Keywords: polymer concrete, optimization, high temperatures, flame retardant, mechanical properties, physical properties, thermal properties

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Niyigena, César. "Variabilité des performances de bétons de chanvre en fonction des caractéristiques de la chènevotte produite en Auvergne." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22700/document.

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Анотація:

Les origines de la variabilité des propriétés du matériau béton de chanvre sont nombreuses. On distingue celles liées aux propriétés des ses constituants et du matériau lui-même auxquelles il faut ajouter les dispersions qui résultent des méthodes utilisées pour caractériser ce béton. Ce travail de thèse, s’intéresse à l’étude de la variabilité des propriétés du béton de chanvre en tenant compte de ces différentes sources et en particulier au type de chènevotte utilisée. L’étude bibliographique réalisée permet de comprendre le matériau béton de chanvre, notamment ses constituants, les méthodes de caractérisations en usage ainsi que l’ampleur de la variabilité et de la sensibilité de ses propriétés vis-à-vis des différents paramètres. Cet état de l’art, permet en outre d’identifier les paramètres à considérer dans le cadre de cette thèse. Notre travail de thèse est alors subdivisé en 4 chapitres en plus de l’étude bibliographique. Dans le deuxième chapitre, une étude multicritère sur les propriétés des chènevottes est présentée. Après une campagne expérimentale de caractérisation de 13 types de chanvre, une analyse des résultats à deux niveaux est réalisée. Elle prend en compte, la masse volumique, la capacité d’absorption d’eau et la granulométrie. Dans un premier temps on présente les résultats de l’étude mono-caractéristique ; il s’agit de la comparaison d’une caractéristique donnée pour l’ensemble des chènevottes. Dans un second temps, on présente les résultats de l’étude multicritère. Il s’agit d’analyser l’ensemble des chènevottes en prenant en comptes les différentes caractéristiques à la fois. A l’issue, les chènevottes sont classées en trois groupes. Le chapitre 3 constitue une étude préliminaire tenant compte des différents paramètres sources de variabilités des propriétés du béton de chanvre, comme le laboratoire d’essai (équipements), la gâchée, la taille d’éprouvette et le type de chanvre. Les résultats obtenus montrent la nécessité d’étudier l’impact du type de la chènevotte. Par ailleurs, la dispersion considérable obtenue pour les résultats du module d’Young est vraisemblablement associée à sa méthode de calcul. Il devient alors important d’approfondir l’étude de son impact sur les valeurs du module d’Young obtenues. Le chapitre 4 vise justement à étudier les méthodes de calcul du module d’Young. Les différentes méthodes de la littérature sont alors utilisées pour exploiter les courbes contrainte-déformation dont les essais ont été réalisés dans les mêmes conditions. Les variabilités observées sur les résultats vis-à-vis de chacune des méthodes permettent alors de mettre en évidence leur impact et de proposer la méthode « flottante » comme étant la plus pertinente. Par ailleurs, un modèle permettant de décrire la loi de comportement mécanique du béton de chanvre est proposé. Il permet de déterminer la courbe enveloppe correspondant à la courbe expérimentale issue du chargement monotone, et permet également de reproduire la courbe expérimentale issue d’un chargement cyclique. Dans le dernier chapitre, en se basant sur les résultats du chapitre 2, neuf types de chanvre ont été sélectionnés pour la confection des éprouvettes de l’étude. Dans les mêmes conditions (fabrication et essai), il a été mis en évidence expérimentalement l’impact de la chènevotte sur les propriétés mécaniques avec un facteur égal à 10 entre les valeurs faibles et élevées. La réponse mécanique caractérisée par des faibles (<5%), moyennes (>5% et <8%) et fortes (>8% et <20%) niveau de déformation a été mis en évidence. Ces variabilités, restent cependant moins marquées pour la conductivité thermique et la masse volumique du béton de chanvre. L’étude met en évidence l’intérêt d’une étude approfondie sur l’interaction liant/chènevotte pour une meilleure compréhension de l’impact de la chènevotte sur le béton de chanvre
The origins of the variability of hemp concrete material properties are numerous. They include among others those related to the properties of its constituents and material itself as well as the methods used for their characterizations. This thesis is interested in the study of the variability of hemp concrete properties taking into account these different parameters and in particular the type of hemp particles used. The litterature review corried out allowed to present the hemp concrete material, the properties of its constituents, their methods of characterization and also the extend of properties variability and sensitivity due to various parameters. Furthermore, it allowed to identify the parameters to be considered in the context of this thesis. Therefore, this thesis is devided into four chapters in addition to the literature review. In the second chapter, a multi-criteria study on the properties of hemp particles is presented. After an experimental study of characterization for 13 types of hemp particles, a two level analysis of result is performed. It takes into account the density, water absorption capacity and particle size distributions. First, the results of the single characteristic study are presented; it is about a comparison of a given characterstic for all hemp particles at the same time. Secondly, the results of the multi-criteria study are presented. In this last case, the analysis is corried out by taking into account all hemp particles and characteristics, both at the same time. The outcome of this study allowed to classify hemp particles into three groups from which, low, medium and high mechanical peformances are expected, respectively. Chapter 3 is a preliminary study taking into account various parameters as sources of variability for hemp concrete properties, such as the testing laboratory (equipments), the batch, the specimen size and hemp particles type. The obtained results highlight the need for further investigations about the impact of hemp particles type. Moreover, the considerable dispersion in the results of Young’s modulus is likely associated with its calculation method. It then becomes important to deepen the study of its impact on the values of Young’s modulus obtained. The chapter 4 aims to answer the problem found on the method for calculating the Young’s modulus. Various methods from literature are used to analyse the stress-strain curves from samples manufactured under the same conditions. The variability observed in results with respect to used method allowed to highlight their impact and to provide the floating method as the most pertinent since it presents less variability. In addition, a model to describe the mechanical behavior law of hemp concrete is proposed. It allows to determine the enveloppe curve which corresponds to experimental curve from the monotonic loading. It can also allow to reproduce the experimental curve from a cyclic loading. In the last chapter, based on the results of chapter 2, nine types of hemp particles were selected for the preparation and manufacturing of specimens of the study. Under the same conditions (manufacturing and test), it has been demonstrated experimentally the impact of hemp particles on mechanical properties with a factor 10 between low and high values from obtained results. The mechanical response characterized by low (<5%), medium (>5% and <8%) and high (> 8% and <20%) level of deformation have been highlighted. These variabilities remain, however less marked for thermal conductivity and density of hemp concrete material. This study highlights the interest of a comprehensive study on the interaction binder/hemp particles for a better understanding of the impact of hemp particles on hemp concrete

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Kallel, Hatem. "Influence de la température et de l'hygrométrie sur le comportement instantané du béton." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3013/document.

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Les enceintes de confinement sont sollicitées lors d'un accident grave par la modification thermodynamique du milieu interne qui génère une pression pouvant monter jusqu'à 5 bars, une température évaluée au maximum à 180 °C et une humidité relative pouvant aller jusqu'à la saturation. Au-delà de calculs réglementaires, la complexité de la sollicitation nécessite une bonne connaissance du comportement mécanique et thermique des matériaux et en particulier du béton dans la gamme de température et d'hygrométrie imposée afin d’être capable de mener les simulations numériques les plus réalistes possibles.Notre étude présente les évolutions des caractéristiques mécaniques et thermiques essentielles pour les simulations numériques d'un béton dans la plage de pression, température et humidité imposées lors d'un accident grave. Les essais mécanique et thermique sont réalisés sous chargement thermo-hydrique contrôlées. La température (T) est fixée à cinq valeurs cibles : 30, 90, 110, 140 et 160 °C. Les cinq degrés de saturation en eau liquide du béton (Sw) varient entre 36 % et 100 %. Les différents degrés de saturation en eau liquide des éprouvettes sont obtenus par le contrôle de l’humidité relative de l’ambiance entourant l’éprouvette pendant leur cure. L’essai DCT (Disk-shape Compact Tension) a été choisi pour déterminer l’évolution de l’énergie de fissuration, du module d'élasticité et de la résistance en traction en fonction de la température et de Sw, en raison de son caractère très compact favorable pour la mise en oeuvre des essais sous pression (essai au-delà de 100 °C). Les propriétés thermiques sont évaluées par la méthode de la Source Plane Transitoire (TPS). C’est une technique permettant de déterminer la conductivité thermique, la diffusivité thermique et d'en déduire la chaleur spécifique. L’évolution de la perméabilité relative à l’azote du béton en fonction de la température jusqu'à 90 °C et du degré de saturation en eau du béton a été évaluée également. Après avoir déterminé les propriétés thermiques et mécaniques du béton, une modélisation numérique a été réalisée afin de passer de l’échelle de laboratoire à l’échelle de la structure. Un couplage entre un modèle hydrique et un modèle d’endommagement a été réalisé
In case of severe accident, confinement chambers are submitted to thermodynamic variations of their internal environment. Pressures can increase up to 5 bars, temperature reaches 140 °C and relative humidity attains saturation. Beyond regulatory calculations, the complexity of the solicitation needs a good knowledge of the thermo-mechanical behaviour of concrete under the imposed conditions of temperature and relative humidity. This, in turns allows to develop numerical simulations as realistic as possible. The present study investigates the evolution of the mechanical and thermal characteristics of concrete. These properties are essential to develop numerical computations under the levels of pressure, temperature and relative humidity imposed during a severe accident. Mechanical and thermal tests are carried out under controlled hydro-thermal conditions. Temperature (T) is fixed at five target values: 30, 90, 110, 140 and 160 °C. Five levels of degree of saturation (Sw) range from 36 % to 100 %. The different target values of degree of saturation are attained by controlling relative humidity in the surrounding environment of the specimens during curing. DCT (Disk-shape Compact tension) tests was chosen to determine the dependence of the fracture energy, elastic modulus and traction resistance on temperature and degree of saturation of concrete because of its compact shape that is more suitable for testing under pressure (temperature above 100°C). Thermal properties are determined by means of the Transient Plane Source (TPS) method. This technique allows to determine thermal conductivity, thermal diffusivity and hence to deduct specific heat. The dependence of the permeability to liquid nitrogen on temperature up to 90 °C and on the degree of saturation was also analysed. After determining thermal and mechanical properties of concrete, numerical simulations have been developed in order to pass from laboratory scale to the structure scale. A coupled hydro-mechanical model and a damage model are proposed

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Pilík, Václav. "Bydlení pro seniory." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-410076.

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The diploma thesis is elaboration of project documentation of the object Housing for seniors in Brno - Dolní Heršpice. The site is located un the area with the planned development of the city. The object is detached, three-story with a partial basement. The building is divided into five parts. The building is based on concrete foundation pads and strips. The structural construction is a combined column and wall system in technological design as monolithic concrete. The building is designed as a low energy building, with contact insulation (ETICS). The whole building is designed with forced air exchange. An extensive and intensive walkable flat roof is designed. The aim is to create small, barrier-free, community housing with affordable services and support, with a possible life expectancy. Services for the elderly with reduced self-sufficiency and with mild health and mental dysfunctions are considered. The building is equipped with space for accommodation with a capacity of 48 beds, space for eating with a separate kitchen, space for leisure and physical activities, space for basic health and social care and space for administrative and technical facilities. The construction is divided into several buildings, the subject of the thesis is primarily the solution SO.01 - Housing for seniors

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Navrátil, Michal. "Centrální požární stanice Svitavy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-410054.

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The diploma thesis elaborates the project documentation for the construction of a new apartment of central fire station type C1 with the administrative part of the Territorial Department. The fire station is technologically linked to the second building SO.02 the technical and technological background of the fire station. The building is situated on the eastern edge of Svitavy. The building is non-cellular, it has three floors and a flat green roof. Three floors fulfilling matter with mainly administrative function is connected with two floors blocks fire station with an indoor gym. Above the floor containing garages for emergency vehicles facilities for the emergency unit are placed with a curtain that creates fading of the emergency door. The matter of the gym is optically separated from the station and highlighted with a volume narrow neck and height elevation. In the station there are training places and places for general physical preparation. The buildings are located in a sloping terrain. The ground fire station has a heliport. The establishment supporting columns of the building are for made of prefabricated calyx, and are concreted into monolithic foundation pads. Infill wall vertical bearing and non-bearing structures are designed from clay blocks type THERM. The bearing system is reinforced concrete prefabricated frame. Horizontally bearing structures are designed from prestressed hollow core slabs. The building envelope is made of a curtain wall in dark grey and red combined with a light contact thermal insulation system used on the indoor gym. The envelopes are in the administrative part and the part of the station divided by a glazed area. In the workshops and technology room the envelope is divided by lamellae. Usually there are 13 firemen during one shift, in three shifts there work 39 firemen all together. There are supposed to be 17 employees in the administrative department.

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31

Adelzadeh, Masoud. "Structural and Thermal Behaviour of Insulated FRP-Strengthened Reinforced Concrete Beams and Slabs in Fire." Thesis, 2013. http://hdl.handle.net/1974/8287.

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Despite the superior properties of Fibre Reinforced Polymer (FRP) materials, the use of FRPs in buildings is limited. A key cause of concern for their use in buildings arises from their poor performance in fire occurrences. This thesis presents the results of fire performance of Reinforced Concrete (RC) beams and slabs strengthened with externally bonded FRP sheets. The performance and effectiveness of insulation materials and techniques are also investigated in this thesis. Two full-scale reinforced concrete T-beams and two intermediate-scale slabs were strengthened in flexure with carbon and glass fibre reinforced polymer sheets and insulated with a layer of spray-on material. The T-beams and slabs were then exposed to a standard fire. Fire test results show that fire endurances of more than 4 h can be achieved using an appropriate insulation system. Tests were performed in order to understand the behaviour of FRP concrete bond at high temperatures. An empirical model was then formulated to describe the bond strength deterioration due to temperature rise. Innovative measurement techniques were employed throughout the experiments to measure important observables like strain and temperature. Meanwhile, the effectiveness and practicality of techniques such as Fibre Optic Sensing (FOS) and Particle Image Velocimetry (PIV) for high temperature applications were investigated. A numerical finite-volume heat transfer model was developed to simulate the heat transfer phenomenon. The validity of the numerical model was verified by comparing the results with the results from the fire tests. By using this model, parametric analyses were performed to investigate the effect of different fire scenarios on the performance of the insulated beams. To simulate the structural performance of the T-beams a numerical model which was capable of predicting stresses and strains and deflections of a heated beam was developed. The model is capable of incorporating the effects of axial forces in the response of a restrained beam. This model was verified and used in combination with the thermal model to simulate the deflections of T-beams in fire.
Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-09-17 15:11:16.185

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32

Riding, Kyle Austin 1978. "Early age concrete thermal stress measurement and modeling." Thesis, 2007. http://hdl.handle.net/2152/3281.

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A large amount of heat can be liberated during cement hydration, causing very large temperature increases in mass concrete members. The non-uniform temperature field produced by the cement during curing can cause very high internal stresses that may crack the concrete. Concrete thermal cracking in very large structures is a well-known phenomenon and was studied extensively during the height of dam construction in the United States. In recent years concrete bridge member sizes have increased for structural and aesthetic reasons. Recent problems in San Antonio and Houston, Texas with thermal cracking and very high internal temperatures in mass concrete bridge members has renewed interest in studying early-age thermal cracking and its mechanisms. In order to predict the early-age thermal cracking risk of a concrete member, the temperature history, autogenous shrinkage, modulus development, tensile strength development, coefficient of thermal expansion development, creep behavior, and external restraint conditions must be known. A testing procedure has been developed to measure concrete heat of hydration, mechanical property development, and free shrinkage response at different curing temperatures. The concrete free shrinkage includes thermal and autogenous shrinkage components and is measured using a newly developed free shrinkage testing apparatus. The early age concrete creep is calculated from rigid cracking frame tests performed at different varying temperatures. Trends in early age creep behavior for different concrete mixtures common in mass concrete have been found and are used to develop a statistical model relating concrete mixture proportions and constituent material properties for use in mass concrete thermal stress modeling. The results from the test methods described are used in a new concrete early-age cracking risk and durability software package called ConcreteWorks.
text

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33

Gibbon, George James. "Laboratory test procedures to predict the thermal behaviour of concrete." Thesis, 1995. https://hdl.handle.net/10539/25060.

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A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy
The cracking of mass and structural concrete due to thermal stress is a major problem in the concrete construction industry. Concrete will crack when the thermal stress exceeds tbe tensile strength of the concrete, Decisions on the type of concrete mix, cooling facilities and construction techniques to be used in the erection of a concrete structure can only be made if the thermal behaviour and strength of the concrete can be predicted during hydration. This thesis describes the development of a low cost, computer controlled, adiabatic calorimeter to determine tlte heat of hydration and a probe to determine the thermal conductivity or concrere samples. The main thrust of this thesis is the development of the thermal conductivity probe which, for the first time, can measure the thermal conductivity of concrete through all stages of hydration. A thermal model was also developed to verify the results, and the use of the calorimeter for temperature matched curing tests is also discussed. Results, obtained from the test procedures described, will provide far more accurate predictions of the temperatures in concrete structures than was possible in the past.
Andrew Chakane 2018

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34

Poole, Jonathan Larkin 1977. "Modeling temperature sensitivity and heat evolution of concrete." Thesis, 2007. http://hdl.handle.net/2152/3470.

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The hydration of cement in concrete is exothermic, which means it gives off heat. In large elements, the heat caused by hydration can dissipate at the surface, but is trapped in the interior, resulting in potentially large thermal gradients. The thermal expansion of concrete is greater at higher temperatures, so if the temperature differential between the surface and the interior becomes too great, the interior will expand more than the exterior. When the thermal stress from this mis-matched expansion exceeds the tensile strength of the material, the concrete will crack. This phenomenon is referred to as thermal cracking. Accurate characterization of the progress of hydration of a concrete mixture is necessary to predict temperature gradients, maximum concrete temperature, thermal stresses, and relevant mechanical properties of concrete that will influence the thermal cracking risk of concrete. Calorimetry is the most direct test method to quantify the heat evolution from a concrete mixture. There is currently no model, based solely on calorimetry, which completely describes the effects of mixture proportions, cement and SCM chemistry, and chemical admixture dosages on the temperature sensitivity and adiabatic temperature rise of concrete. The objective of this study is to develop a comprehensive model to describe these effects. First, the temperature sensitivity of the hydration reaction (described with activation energy, E[subscript a]) is needed to accurately predict the behavior of concrete under a variety of temperature conditions. A multivariate regression model is from isothermal calorimetry testing to describe the effects of water-cementitious materials ratio, cement chemistry, supplementary cementing materials, and chemical admixtures on the E[subscript a] of portland cement pastes. Next, a multivariate regression model is developed from semiadiabatic calorimetry testing that predicts the temperature development of concrete mixtures based on mixture proportions, cement and SCM chemistry, and chemical admixture dosages. The results of the models are validated using data from literature. The final model provides a useful tool to assess the temperature development of concrete mixtures, and thereby reduce the thermal cracking risk of the concrete structure.

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35

Ting, Yu-Sheng, and 丁昱升. "The thermal properties of light-weight concrete after a fire." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/93499185479684606248.

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碩士
國立交通大學
土木工程研究所
83
If the light-weight concrete is used in building a high rise ,it can reduce building''sweight because of its weight is lighter than the normal-weight concrete,and reduce the process of earthquake corresponding.On the other side,its fire proof properties are better than the normal-weight concrete.In these years,fire damage made great losses of life and money,if we want to employ the light-weight concrete to building structure, it is necessary to research its thermal properties in the process of a fire. The research has different aggregates of four specific gravity in making concrete,heated with ASTM E119 standard fire temperature-time relation to 1052 ℃,measure their surplus strength,weight,dynamic elastic modulus, ultrasonic velocity after cooling,temperature-time relation in concrete interior during heating,and concrete''s extreme thermal expansion strain, thermal expansion cofficient. With the result that we can see the thermal properties of the light-weight concrete after a fire are better than the normal-weight concrete,so if a construction is built in the light-weight concrete,it can reduce fire damage effectively.

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36

楊育澤. "Study of Different Materials to the Thermal Properties of Concrete." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/20857024426795726022.

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碩士
國立交通大學
土木工程學系
100
ABSTRACT The center temperature of a mass concrete may be high due to hydration. If the heat conduction of concrete can be increased such that the heat can be dissipated from center to the environment would be a good idea. In addition, if the heat can be absorbed and transferred to other places in a fire, the temperature difference of the concrete may be reduced and the cracks may be minimized. In our daily life, the heat from Sun can be used captured easier for further use and a more sustainable structure can be achieved. This research used a more heat-conducting material to replace conventional fine aggregates for this purpose. Materials b, c, d, g, and w were used as fine aggregates to study the effects on the compressive strength, expansion under heat, heat conduction, specific heat, and electrical resistance. The test results showed the following: 1. The addition of material b and w increases the compressive strength by 20%. 2. The addition of material d decreases the compressive strength by 14%. 3. The specific heat of the specimen with material d was reduced by 15%. 4. The expansion coefficient under heat is increased by 8% for specimens with materials b and w. 5. The heat conduction coefficient of specimens with materials c, d and g increases 80%. Keywords: concrete, expansion, heat conduction, specific heat, electrical resistance.

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37

Tsai, Jia-Shiuan, and 蔡嘉軒. "The thermal properties of concrete made with industry by-products." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60244697287117335931.

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38

Wang, Wei-Chun, and 王偉峻. "The Thermal Properties of Concrete Made of Industrial By-products." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/01555533141550492564.

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Анотація:

碩士
國立交通大學
土木工程學系
99
This research focused on the thermal properties of concrete. If concrete can have a good thermal conductivity, the thermal stress of mass concrete due to temperature difference can be reduced. Under sunlight, if the heat can be retrieved to be used as alternative energy for lighting, heating, etc, it will be helpful for carbon dioxide reduction and leads to a green building and environment. This research used materials with higher thermal conducting properties to replace conventional aggregate. These materials are designated as coarse aggregates A, B, and C, and a, b, c, d for fine aggregates. The compressive strengths, thermal expansion, thermal conductivity, specific heat, and electrical resistance were studied.

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39

廖侶翔. "Study of the engineering performance Concrete Mixing with Different Thermal Properties materials." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/14853023948585047363.

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40

Kusumawardani, Dana Mutiara, and 古貝華. "Evaluations of Performance and Thermal Properties in Porous Asphalt Concrete Containing Steel Slag." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/22313211576137486539.

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碩士
國立中央大學
土木工程學系
102
Porous asphalt concrete (PAC) is one alternative solution to the problem of stormwater drainage from parking and other low traffic density areas. The overall benefits of porous asphalt concrete may include both environmental and safety benefits including improved stormwater management, improved skid resistance, reduction of spray to drivers and pedestrians, reduction in light reflection and headlight glare, as well as a potential for noise reduction. However, there are disadvantages of this pavement type such as has lower service life than dense mixes. Steel slag is the material generated from purifying metal, their casting and alloying. It is steel slag that can be used as an aggregate substitution. The objective of this study was to evaluate the performance and thermal properties of porous asphalt concrete containing steel slag. Two types of steel slag were used to subtitute coarse aggregate, including Basic Oxygen Furnace (BOF) and Baoshan Slag Short Flow (BSSF). Three different percentages of steel slag, namely 0%, 30%, and 50%, were mixed. Two main aspects are investigated in this study. One is mixture performance, including resilient modulus, rutting potential, skid resistance, and moisture susceptibility test. The other is thermal properties characteristic, including thermal conductivity, thermal heat capacity, and thermal diffusivity. Statistical were utilized to determine which treatment has the best performance result. The test results show that steel slag has higher specific gravity, high absorption, but lower L.A. abrasion, and soundness compared with natural aggregate. PAC containing steel slag may enhance the resilient modulus, skid resistance, rutting potential, and moisture susceptibility. However the application of high percentage of steel slag may decrease the performance of PAC, such as decrease skid resistance, rutting potential, and moisture susceptibility. The statistical analysis results show that PAC containing 30% of BOF slag has the best performance results, however this kind of pavement had the highest thermal conductivity and thermal diffusivity compared with others. The conclusions indicate that both BOF and BSSF slag are suitable to used as coarse aggregate substitution in PAC.

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41

Chen, Po-Huan, and 陳柏寰. "Thermal Properties of Concrete Wall Containing Composite Phase -Change Materials and Numerical Simulation Analysis." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/18614054448818331804.

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碩士
國立臺灣大學
土木工程學研究所
101
In the condition of greenhouse effect and outdoor temperature raised, the heat which enters into the indoor increases. The air conditioning energy consumption will increase, causing the energy shortage. In the study, the phase change materials have the latent heat, which can absorb large amounts of heat. The research is about investigating the characteristics of the phase change wallboard in Taipei weather conditions and the behavior of the indoor ambient temperature performance. There are three parts of experimental and simulation analysis. The first part is the heat conduction properties of the phase change concrete, including the thermal diffusivity, heat capacity and the unit weight in the formula for calculating thermal conductivity. When the amount of phase change materials increased, the concrete is lighter. When the amount of phase change materials increased, the heat capacity is higher. There is a peak on the standard phase transition temperature. Due to the phase change materials resist heat (cold) source from advancing, which concrete adds the phase change materials, the thermal diffusivity will decrease. The final, thermal conductivity in the non-phase change temperature section is lower, when the amount of phase change materials increased. In the phase change temperature section, the thermal conductivity coefficient curves overlap. Addition of 10%, 20% and 30% thermal conductivity peaks are 1.73 W/m∙K, 1.61 W/m∙K and 1.67 W/m∙K, which are lower than the thermal conductivity (2.0 W/m∙K) of the concrete without adding the phase change materials. The second part is hot box tests. Our group uses the hot box instrument in NTU civil engineering materials laboratory, sets Taipei 2012 summer temperatures, winter temperatures and design cycle temperature as schedule of testing. In summer test, when the amount of phase change materials increased, the indoor high temperature is lower and high-temperature peak time of occurrence delays. In winter test, found that addition of the phase change materials causes the rising of low temperature. The cycle test of 20℃~40℃, 12 hours a cycle, adding phase change materials, the temperature can be controlled in a small temperature range. The the temperature differences of addition of 0%, 10%, 20%, 30% are 9.6℃, 7.4℃, 5.7℃, 5.1℃, but the delay time are shorter than the summer test results. The third part is ABAQUS simulation analysis for the cycle test. Comparing the results for the phase transition temperature of the material added control behavior, software simulations have accurate results. Temperature peak delay phenomenon in the software simulation can also be seen.

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42

Chuang, KunBin, and 莊昆斌. "Study of Steam Curing on the Thermal Properties and Engineering Properties of Self-Compacting Concrete with Various Slag Additions." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/89670482680960321830.

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碩士
國立臺灣科技大學
營建工程系
92
This research used the Hot Wire Method by embedding a thermal needle probe to a hole of concrete cylinder to study the effects of steam curing on the thermal properties and engineering properties of self-compacting concrete with three kinds of slag additions condition (0%, 20%, and 40%). Subsequently, the effects of various slag additions on the thermal conductivity of concrete together with three kinds of curing condition (normal curing, steam curing 50℃, steam curing 70℃) were investigated. Finally, the effects of various curing conditions and various compositions on the engineering properties and thermal conducting behavior at setting stage of self-compacting concrete were studied. Experimental results show that (1) After 28 days, for sets of 0%, 20%, 40% slag addition, thermal conductivity decreases by steam curing; (2) For concrete specimens at all ages, under normal curing condition, the set of 20% slag addition has the maximum value of thermal conductivity. Under steam curing 50℃ condition, the set of 40% slag addition has the maximum value of thermal conductivity. After 28 days, under steam curing 70℃ condition, the value of thermal conductivity of the set of 20% slag addition is similar to the set of 40% slag addition; (3) The coefficient of thermal conductivity increases by 59.04%(normal curing), decreases by 7.39%( steam curing 50℃), and decreases by 40.29%(steam curing 70℃) for the set of 20% slag addition on the 56-day age. The coefficient of thermal conductivity increases by 33.48 %( normal curing), increases by 55.86 %( steam curing 50℃), decreases by 41.83 %( steam curing 70℃) for the set of 40% slag addition on the 56-day age; (4) Under the normal curing, concrete cylinder with 40% slag addition has the maximum compressive strength. Under the steam curing, concrete cylinder with 20% slag addition has the maximum compressive strength. Results show that under normal curing, the higher the slag addition is, the higher its long-term compressive strength will be. Under steam curing, the set of 20% slag addition obtains the best self-curing capability.

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43

Pu, Weimin. "An investigation on mechanical and thermal properties of lightweight concrete based on the wood-cement system." Thesis, 1992. http://spectrum.library.concordia.ca/2483/1/MM80916.pdf.

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Shows that concrete made with maple sawdust has low bulk density with moderate strength, as well as low thermal conductivity and high durability, making it usable for residential and commercial building construction for energy conservation.

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44

HSU, YU-WEN, and 徐郁雯. "The Study of Thermal Properties and Rapid Chloride Permeability Testing in Concrete Containing Reclaimed Asphalt Pavement." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6v4d87.

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碩士
國立高雄科技大學
土木工程系
107
The research objective was to assess the mechanical properties, shrinkage, thermal expansion and conductivity, and chloride penetration of concrete containing reclaimed asphalt pavement materials. Rich and lean concrete mixtures were blended by water to cementitious materials (w/c) ratio of 0.5 and the RAP materials were replacing both coarse and fine aggregates by 0, 20, 40, 60, 80, and 100-%. The concrete cylinders and specimens were cast and cured in the water tank for 7, 28, 56, and 90 days. The test results demonstrate as follows: the mixing temperatures of all concrete mixtures increased among 24.5 and 26.8, from 20-°C; the unit weight, compressive strength, pulse velocity, and shrinkage decreased, when more percentage of RAP were incorporated; thermal conductivity increased when more percentage of RAP were added. However, thermal conductivity decreased when longer curing time of concrete were given; thermal expansion also increased when more percentage of RAP were blended; lastly, the coulombs or charge pass indicating the chloride penetration increased on 90-day moisture-cured concrete specimens, when more RAP were replaced.

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45

Wen, Kai-ling, and 溫凱翎. "Hardened Properties and Thermal Conduction of Concrete with Fly Ash and Slag Additions under High Ambient Temperature." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/d2u75m.

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碩士
國立臺灣科技大學
營建工程系
94
This research used the same water-binder ratio (W/B = 0.6) to study the effects of fly ash or slag on the properties of concrete under steam curing. This study also used a one-dimensional heating test module of 7 × 7 × 55 cm to study the effects of fly ash and slag on the thermal conduction of concrete, and to compare the difference of properties of harden concrete at the locations away from the heating surface. Experimental results show that: (1) The hydration and Pozzolanic reaction speeded up by steam curing, such that the 3-day compressive strength of steam-cured concrete was higher than that of the water cured, and this condition becomes more obvious with more Pozzolanic replacement, especially for fly ash; (2) The surface electrical resistivity of the steam-cured concrete with fly ash was much higher than the water-cured , and had a substantial increase with even higher fly ash replacement; (3) The thermal conducting speed of fresh concrete was obviously higher, which showed that the degree of saturation had a positive correlation with the thermal conductivity rate; (4) After 28 day, the thermal conductivity rate of concrete with the replacement of 30% slag was much lower than the others; the replacement of 30% fly ash (F30) and 15% slag (S15) were the next high, and the normal-weight concrete and mortar were the highest; (5) The difference in the properties of harden concrete at different layers in the one-dimensional heating test were not apparent, due to the fact that, during the earlier stage of the test, the concrete specimens were also subjected to the thermal conduction from the surrounding lateral surfaces.

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46

Li, Shu-wei, and 李書緯. "Study on the Properties of the Light-Aggregate Concrete by Using the Infrared Thermal Graphy and Ultrasonic Method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/10483359296017114611.

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Анотація:

碩士
國立高雄應用科技大學
土木工程與防災科技研究所
93
This research is focused on taking the light aggregates which is produced by sintering the sludge of the reservoir of the A-Gon-Den impound in Kaoshiung, to make the light aggregate concrete based on the densified mixture algorithm. This concrete has been conducted the destructive and non-destructive testings in order to identify properties and to establish their reciprocal relations, accordingly. While designing light-aggregate concrete, and three groups of W/B (0.28 & 0.32&0.40) were used to mix the sludge light aggregate concrete. At the other hand, two kinds of mixture water volume (160,170 kg/m3), three different ratios of water to binder ratio (W/B＝0.28, 0.32, 0.40), of light aggregate concrete were conducted tests of fresh property( such as slump and slump flow), hardened property and durability (such as compressive strength, electrical resistivity, chloride ion penetrability and thermal conductivity ), and non-destructive property (such as infrared thermal graphy and ultrasonic method). Moreover, the portion of the specimens will be taken for the interface micro-structure by FSEM test. All related data were collected and analyzed to identify the interrelation in order to have a better understanding on the latent property of the light aggregate concrete by using the sintered reservoir sludge of A-Gon-Den impound in Kaohsiung. It’s hopeful to provide the southern Taiwan the operation reference of the high performance light-aggregate concrete and to establish a much more complete database of light aggregates of the southern Taiwan.，LWC’s slump and slump flow achieve 250mm and 550mm,ACI achieve 150mm and 200mm, Concrete Resistivity achieve 53 kΩ-cm,ACI achieve12 kΩ-cm, 1.1 aggreage density between 1.61g/cm3~1.62 g/cm , Compress strength between 67.7Mpa~71.2Mpa, Ultrasonic between 3789m/s~3846m/s, 1.3 aggreage density between 1.40g/cm3~1.64 g/cm3, Compress strength between 36.7Mpa~59.6Mpa, Ultrasonic between 3707m/s~3884m/s, 0.8 aggreage density between 1.47g/cm3~1.63 g/cm3, Compress strength between 42.8Mpa~56.3Mpa, Ultrasonic between 3608m/s~3904m/s,Infrared Thermal Graphy have 2℃ distance between first floor and last floor.

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47

Lin, Kun-te, and 林坤德. "The Influence of Steel Fiber and Silica Sand Contents on Thermal and Mechanical Properties of Reactive Powder Concrete." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/93504354505642023542.

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Анотація:

碩士
國立臺灣科技大學
營建工程系
93
The study presents the experimental results of thermal properties, mechanical properties, SEM and MIP of Reactive Powder Concrete(RPC) with different steel fiber content (0%, 1%, 2%), silica sand content (VS/VC=1.6, 1.8, 2.0), and curing temperature (25℃, 55℃, 85℃ at relative humidity 95%), on the conditions of two different water contents (0% and 100%). Experimental results show that: (1) Compressive strength, UPV, dynamic modulus of elasticity, dynamic modulus of rigidity, Poisson’s ratio, thermal conductivity and thermal diffusivity increase with increase of steel fiber content, except for specific heat；(2) Mechanical properties increase with increase of silica sand content in the condition of curing temperature at 25℃ and 55℃, but decrease at 85℃；(3) All of the thermal properties improved with increase sand content at 25℃ and 55℃. Specific heat is the lowest when sand-to-cement ratio equals to 1.8；(4) Thermal conductivity, thermal diffusivity, and specific heat of specimen at the condition of 0% water content are lower than those of 100% water content；(5) According to SEM, micro-structure of reactive powder concrete is very dense, but more porosity forms in the transition zone between steel fiber and paste；(6) According to MIP, there are more porosities in reactive powder concrete with the addition of steel fiber, but the size of pore becomes lesser.

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48

XIE, YA-XUAN, and 謝亞璇. "A Study on Thermal Insulation Properties of Inorganic Mineral Powder Coating Materials Containing Color Materials in Concrete Buildings." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7n6q64.

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Анотація:

碩士
國立臺北科技大學
土木工程系土木與防災碩士班
107
The inorganic mineral powder coating materials have the functions of reflection and insulation, which can be divided into two types: Cement (UU620) and Geopolymer (UU500). The coated materials have six colors of white, red, blue, green, yellow and gray which are capable of reflecting and blocking part of the radiation heat into the concrete building. The reflectivity and thermal conductivity of inorganic mineral powder materials were measured by spectrometers and heat conduction instrument, respectively; and measurement of adhesion according to ASTM D3359. Notably, the obtained results show that the coating materials have high reflectivity values, excellent thermal conductivity, and the adhesion of different colors is quite good. Through the visible light and infrared radiation concrete plate specimens, the result of turning the light on and off, the upper and lower heat flux, surface and environmental temperature were measured to explore the insulation and cooling effect in different colors. Moreover, it possesses the excellent thermal insulation. Finally, the coated concrete plate has better thermal insulation ability than the uncoated concrete plate in situ test. Through the above-mentioned heat flux experimental data and the formula set by the Green Building Technical Specification, the heat transmission rate of the coated specimen has calculated.

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49

Appuhamilage, Galhena. "Effects of Blast Loading on Reinforced Concrete Facade Systems." Thesis, 2015. https://vuir.vu.edu.au/29785/.

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Facade systems are an integral part of modern day construction, especially with reinforced concrete structures. These facade systems are typically designed to withstand the effects of normal service loads and severe weather conditions. However, these elements are rarely designed to withstand the effects of an external explosion, which is considered as a rising threat to structural safety with the recent escalation of terrorist activities. In addition, these facade systems will act as the first layer of defence against an external explosion limiting the damage to the main structure. The aim of this research is to study the effects of blast loading on reinforced concrete facade systems. More specifically, the behaviour of reinforced concrete facade panels with flexible support conditions will be investigated. The overall aim was pursued by evaluating and utilising experimental studies relevant to this research to undertake 3-D finite element modelling using LS-DYNA and 1-D analytical modelling using a theoretical development. The validated numerical and analytical models were then utilised in a comprehensive parametric study.

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Ho, Kuo-Yi, and 何國意. "Water Absorption Characteristic of Lightweight Aggregates and its Effect on the Thermal and Mechanical Properties of Lightweight Aggregate Concrete at Elevated Temperatures." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/43787628614886921697.

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碩士
國立中興大學
土木工程學系所
100
The research discuss the water absorption characteristic of lightweight aggregates and its effect on the thermal and mechanical properties of lightweight aggregate concrete. The contexts of the research are separated by two parts. The first part is the basic property tests of the concrete material, including compressive strength, flexural strength, splitting strength, elastic modulus and thermal conductivity. The second part is the to load bearing behavior, fire resistance and heat insulation tests of reinforced concrete beams members and slab members. The experiment variables include pre-wetted time of lightweight aggregates (oven dry, 30 min) and the maximum elevated temperatures (400℃, 600℃, and 800℃). For the property of the concrete material, the experimental results showed that the thermal conductivity of normal concrete is higher than lightweight aggregate concretes at elevated temperature. The main reason is because the multiple pore structure in the lightweight aggregate concretes reduces the thermal conductivity. While at the higher pre-wetted time, the thermal conductivity of the lightweight aggregate concretes slightly reduced due to the lower density. The splitting strength and flexural strength of the lightweight aggregate concretes experimental results showed that, the splitting strength and flexural strength slightly increased at lower than the 400℃ maximum elevated temperature. It is because the water inside the concrete and the cement with un-completely hydrate role were heated by increasing temperature so that the inside water complete role with concrete and promote the flexural strength. For the tests of reinforced concrete beams members and slab members, the experimental results showed that, variations in mechanical and thermal properties due to the elevated temperatures for lightweight aggregate concretes with different pre-wetted time were all smaller the those for normal concrete if the spalling of concrete did not occur. However, there were higher chances to spalling when we choose lightweight aggregates with oven dry. Furthermore, there were no difference of to load bearing behavior at elevated temperature between the pre-wetted time of lightweight aggregates and reinforced concrete beams members and slab members.

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Дисертації з теми "Concrete slabs Thermal properties"

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