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Добірка наукової літератури з теми "Concrete slabs Thermal properties"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 29 січня 2023

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Статті в журналах з теми "Concrete slabs Thermal properties"

Renkas, A. A. "FIRE RESISTANCE PROVIDING OF HOLLOW‐CORE CONCRETE SLABS USING SHEET BUILDING MATERIALS." Fire Safety, no. 34 (July 19, 2019): 72–77. http://dx.doi.org/10.32447/20786662.34.2019.12.

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Introduction. This paper deals with the analysis of world experience in fire resistance providing of hollow‐core concrete slabs. To protect concrete structures are used many structural applications: thermal coatings and materials. The research first analyzes main methods and hypothesis using to make temperature analysis of solution fire resistance of concrete structures. Problem of making temperature analysis of hollow‐core concrete slabs are nonlinear thermal material properties and radiation heat transfer in the hollow-cores. The aim of this paper is to establish the temperature distribution in hollow‐core concrete slab considering radiation heat transfer in the hollow-cores in case of fire in compartment that is spreading by standard temperature-time curve. In addition, the aim is to substantiate the possibility of using gypsum panels to provide fire resistance of hollowcore concrete slabs. Material statement. The paper reports the results of modeling the process of heat transfer in hollow‐core concrete slab, between compartment space and slab surface and in hollow‐cores. To calculate temperature fields in hollow‐core concrete slab considering nonlinear thermal material properties and radiation heat transfer in the hollow-cores was used finite element model. At addition, the results of finite elements simulations show temperature fields in hollow‐core concrete slab and gypsum panels that installed under concrete slab. Scientific novelty. The paper reports results of theoretic substantiated of possibility of using gypsum panels to protect of hollow‐core concrete slabs considering nonlinear thermal material properties, radiation heat transfer between surfaces and radiation heat transfer in the hollow-cores. The results indicate that using gypsum panels to protect of hollow‐core concrete slabs reduces speed heating of concrete elements to critical temperatures that increase fire resistance of hollow‐core concrete slabs to 20.4 %.

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Zhu, Desheng, Ji Ming Liu, and Zeng Wei Liu. "Properties of Profiled Steel Sheet-Concrete Structure under High-Temperature." Applied Mechanics and Materials 174-177 (May 2012): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.113.

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Profiled steel sheet-concrete composite slab is a common structural elements in composite structure, mechanical properties in high temperature and thermal characteristics of the steel-concrete structure are the basis to analyzing structural response while in fire, bonding properties of profiled steel sheet and concrete play a key role in exerting the composite effect of steel and concrete in composite slabs.

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Bellakehal, Hizia, Ali Zaidi, Radhouane Masmoudi, and Mohamed Bouhicha. "Combined effect of sustained load and freeze–thaw cycles on one-way concrete slabs reinforced with glass fibre – reinforced polymer." Canadian Journal of Civil Engineering 40, no. 11 (November 2013): 1060–67. http://dx.doi.org/10.1139/cjce-2012-0514.

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Flexural behaviour of reinforced-concrete slabs has been widely investigated to characterize properties and behaviour of fibre-reinforced polymer (FRP) materials as reinforcement for concrete structures. However, the short- and long-term thermal effects on FRP bars owing to the significant difference between the bars’ coefficients of thermal expansion in the transverse and longitudinal directions are still to be evaluated and may affect the bond properties and the concrete cover thickness after multiple exposures to freeze–thaw cycles. This paper presents the thermostructural behaviour of one-way concrete slabs reinforced with glass FRP (GFRP) that have previously been subjected to mechanical loads of 20% and 30% of the ultimate flexural capacity of reinforced-concrete slabs, simultaneously with short freeze–thaw cycles. Series tests were conducted on FRP-reinforced concrete slabs 500 mm wide, 195–215 mm thick, and 2500 mm long. The thermal cycles were varied from −30 to 60 °C. Four-point bending tests were conducted up to failure of the slabs. The results show that the thermomechanical load applied before bending tests increases the performance of reinforced-concrete slabs, particularly the concrete shear capacity. The deflection predicted from CSA code and ACI guidelines are very close to those obtained from experimental tests; however, the CSA code overestimates the deflection at the service load. The applied thermal cycles have no big influence on the behaviour before shear failure of concrete slabs reinforced with GFRP bars.

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Nagy, Balázs, and Emese Paulik. "Reinforcement-Dependent Thermal Properties of Reinforced Concrete Columns and Slabs." Applied Mechanics and Materials 861 (December 2016): 279–86. http://dx.doi.org/10.4028/www.scientific.net/amm.861.279.

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Energy efficiency aspects are rarely considered during practical structural design. In building energetic calculations, thermal conductivity values from EN ISO 10456:2008 [1] are mainly used, although the standard define concrete’s values only by taking into account the density and the approximate percentage of reinforcement. Details of the structure type (column or slab), reinforcement (e.g. direction, diameter, amount of rebar spacers) and other properties (e.g. concrete composition) are not mentioned. In this research, we uncover the possible relations between the steel content parameters and thermal properties by laboratory measurements of 1:2 scaled reinforced concrete specimens and validated finite element models of columns and slabs with different designed reinforcements. Results shows, that depending on the structure type, design and steel content, there is a difference in the structure’s equivalent thermal conductivity. Our results and experiences of this research possibly can be used in energy conscious structural design practice.

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Martínez-Martínez, Juan Enrique, Felipe Pedro Álvarez-Rabanal, Mar Alonso-Martínez, and Juan José del Coz-Díaz. "Nonlinear Thermo-Structural Analysis of Lightweight Concrete and Steel Decking Composite Slabs under Fire Conditions: Numerical and Experimental Comparison." Applied Sciences 12, no. 18 (September 16, 2022): 9306. http://dx.doi.org/10.3390/app12189306.

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Composite slabs with steel decking profiles are widely used in building construction. However, the literature on the fire resistance of lightweight concrete (LWC) composite slabs with steel decking is limited. In this work, the thermo-structural performance of LWC composite slabs with trapezoidal steel decking was studied under fire conditions. A total of 12 experimental fire tests were carried out using specimens of 160 mm thickness, 1120 mm width and 2030 mm length, in which nine composite slabs were made of LWC and the remaining three slabs were made of normal concrete (NC) to serve as a benchmark for comparison. All the samples were tested in a furnace following EN 13381-5, applying the standardized time–temperature curve and constant load. During the experimental tests, phenomena such as the vaporization of the free water inside LWC, debonding between steel decking and concrete and changes in material properties affected the thermo-structural performance of composite slabs. The test results show that the load-bearing capacity of lighter slabs does not assure the minimum structural behavior of R30. However, the lighter the concrete is, the lower the thermal transmittance, improving the slabs’ thermal performance under fire conditions. Advanced nonlinear numerical models were developed to predict the thermal and structural performance of the studied LWC composite slabs in terms of temperature and time-displacement. The influences of key factors such as vaporization, thermal strains and debonding were included using material properties and a thermal contact conductance interlayer. Finally, the nonlinear models and the experimental results were compared. The difference between the experimental and numerical values was less than 15%, showing that the numerical results were in good agreement with the experimental results. The results of this study also compared the performance of LWC composite slabs with the NC composite slabs, giving rise to interesting conclusions from a practical point of view.

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Park, Hae-Won, Dong-Hyuk Kim, Cha-Sang Shim, and Jin-Hoon Jeong. "Behavior of Airport Concrete Pavement Slabs Exposed to Environmental Loadings." Applied Sciences 10, no. 7 (April 10, 2020): 2618. http://dx.doi.org/10.3390/app10072618.

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The behavior of pavement slabs was measured over a two-year period from the placement of concrete at a construction site in Incheon International Airport using temperature sensors and strain gauges. The influence of various environmental factors on the slab behavior was investigated by collecting weather data. Laboratory tests were conducted to obtain the material properties of the concrete slab, such as the elastic modulus, Poisson’s ratio, and modulus of rupture. The time of final setting of the concrete slab at the zero point of the strain gauges was determined according to the position and depth of the slab using the maturity of concrete obtained by a mortar penetration test. The real and shrinkage strains were calculated according to the position and depth of the slab using the coefficient of thermal expansion of the concrete, strain gauges, and correction factors of the strain gauges. The effects of environmental factors, such as temperature and moisture variations, were analyzed with respect to the strain in the concrete slab for the first seven days and two years after the placement of the concrete slab. The results obtained by the study shall be used to quantify the environmental effects on slabs for developing a method of designing airport concrete pavements.

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Klemczak, Barbara. "Analytical Method for Predicting Early Age Thermal Effects in Thick Foundation Slabs." Materials 12, no. 22 (November 8, 2019): 3689. http://dx.doi.org/10.3390/ma12223689.

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Prediction of hydration temperature and induced stresses in mass foundation slabs, due to the hydration effects is a difficult task. The complexity of this issue is compounded by transient and non-linear thermo-mechanical phenomena as well by a significant number of contributing technological and material factors that affect the early-age volume changes. This is a probable reason for the limited number of simple analytical methods allowing for the estimation of these effects. This work presents a new proposal in the discussed field. The submitted analytical method for determining the hydration temperature rise, its differentials at a cross-section and induced thermal stresses in mass concrete foundation slabs considers the majority of important technological and material factors, such as the initial temperature of the concrete, the ambient temperature, the thermal properties of the concrete and the heat exchange conditions on the slab surfaces. In stress analysis, both self-balanced and restraint stresses are calculated. Finally, the method is validated in FE analysis conducted for the slabs with various heights and made of different types of cements, as well as by the thermal measurements from the construction site. Due to the limited number of methods allowing for the analytical estimation of the early age thermo-mechanical effects in slabs, this new proposal can be useful in the assessment of these effects.

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Wang, Yabo, H. T. Liu, G. F. Dou, C. H. Xi, and L. Qian. "Experimental Study of Multi-Ribbed One-Way Composite Slabs Made of Steel Fibre, Foam, and Normal Concrete." Archives of Civil Engineering 64, no. 2 (December 31, 2018): 79–96. http://dx.doi.org/10.2478/ace-2018-0018.

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Abstract This paper aims to study the effect of reinforcement configuration (steel fibre and rebar) on the mechanical performance of composite slabs of the same total steel contents. We manufactured four pieces of fullscale multi-ribbed composite prefabricated slabs with different reinforcement configurations by using steel fibrereinforced concrete, foam concrete, and normal concrete. The multi-ribbed composite prefabricated slab has many excellent properties, such as light weight, good thermal and sound insulation. Thus, it can be applied to fabricated structures. In addition, the composite prefabricated slabs with the same total steel contents but with different reinforcement configurations were studied under the same static load, and many technical indicators such as crack resistance capacity, yield load, ultimate load capacity, maximum deflection, destructive pattern, and stress of steel rebar were obtained. Results indicate reinforcement configuration has a significant effect on the mechanical performance of composite prefabricated slabs with the same total steel contents, and composite prefabricated slabs reinforced with longitudinal rebar and steel fibre (volume fraction is 1.5%) have the best mechanical performance and ductility.

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Son, Dong-Hee, Hyo-Jun Ahn, Joo-Hong Chung, Baek-Il Bae, and Chang-Sik Choi. "Deflection Estimation Based on the Thermal Characteristics of Composite Deck Slabs Containing Macro-Synthetic Fibers." Materials 14, no. 14 (July 20, 2021): 4052. http://dx.doi.org/10.3390/ma14144052.

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The purpose of this study was to evaluate the structural performance of composite deck slabs containing macro-synthetic fibers. after a fire by proposing a deflection estimation method for non-fireproof structural decks. Therefore, this study evaluated the fire resistance performance and deflection of deck slabs mixed with macro-synthetic fibers. Afterward, the deflection estimation method considering the thermal characteristics of concrete and deck plates was proposed. A material test was first conducted to evaluate the mechanical properties of concrete mixed with macro-synthetic fibers. This test found that the compressive strength and elasticity modulus of concrete mixed with macro-synthetic fibers was greater than that of general concrete. A flexural tensile test confirmed that residual strength was maintained after the maximum strength was achieved. The fire resistance of the deck slab was adequate even when a fire-resistant coating was not applied. The internal temperature was lowest for the specimen with macro-synthetic fibers. Deflection was evaluated using previously published equations and standards. The deflection evaluation confirmed that the temperature distribution should be applied differently in the estimation method that uses the thermal load of the deck slab.

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Necib, Hichem, Djamel Belatrache, Hafnaoui Goutar, and Nesrine Sahraoui. "Experimental Study of Thermal Conductivity of Concrete with Biosourced Material for Saved Energy in Buildings." Annals of West University of Timisoara - Physics 64, no. 1 (November 28, 2022): 158–71. http://dx.doi.org/10.2478/awutp-2022-0011.

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Abstract This study aims to improve the thermal efficiency of concrete slabs by introducing a plant material. This can contribute to the improvement of internal thermal comfort for buildings and this by lower energy consumption. For this, several experiments were carried out at the laboratory, to find the thermal properties of a new innovative building material produced by inserting ALFA (STIPA TENACISSIMA) into a concrete slab. Several mass percentages of ALFA relative to the total mass of the concrete slab (0%, 0.4%, 0.8%, 1.2% and 1.6%) were studied to see the effect of the introduced quantity of this plant on the thermal conductivity of concrete. It was concluded that the insertion of ALFA in the concrete, decreases considerably the thermal conductivity. The best results are noticed for 1.2% of ALFA, whose thermal conductivity of the concrete is reduced up to 50.61%. As a result, heat gains and losses, through wall or slab, are significantly reduced, which reduces the energy consumed by cooling and heating of homes. In addition, the degree-day method was used to calculate the costs of cooling and heating energy for 58 regions in Algeria. The lowest total energy cost is noticed in the TENES region, while the highest energy cost is noticed in the BORDJ B. MOKHTAR region.

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Дисертації з теми "Concrete slabs Thermal properties"

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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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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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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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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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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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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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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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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Анотація:

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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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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Книги з теми "Concrete slabs Thermal properties"

Bahnfleth, William P. Three-dimensional modelling of heat transfer from slab floors. Champaign, Ill: US Army Corps of Engineers, Construction Engineering Research Laboratory, 1989.

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R, Naik Tarun, American Society for Testing and Materials. Committee C-9 on Concrete and Concrete Aggregates., and Symposium on Temperature Effects on Concrete (1983 : Kansas City, Mo.), eds. Temperature effects on concrete: A symposium sponsored by ASTM Committee C-9 on Concrete and Concrete Aggregates, Kansas City, MO, 21 June 1983. Philadelphia, PA: American Society for Testing and Materials, 1985.

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Angelakos, Bill. Experimental study of reinforced concrete slabs subjected to thermal and mechanical loads. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1993.

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V, Zhukov V. Termostoĭkostʹ zhelezobetonnykh konstrukt͡s︡iĭ. Kiev: "Budivėlʹnyk", 1991.

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Shengxing, Wu, ed. Da ba hun ning tu zao qi re, li xue te zheng ji kai lie ji li. Zhengzhou Shi: Huang He shui li chu ban she, 2010.

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Trapeznikov, L. P. Temperaturnai͡a︡ treshchinostoĭkostʹ massivnykh betonnykh sooruzheniĭ. Moskva: Ėnergoatomizdat, 1986.

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Nat͡sievskiĭ, I͡Uriĭ Danilovich. Povyshenie teplozashchitnykh svoĭstv paneleĭ iz legkogo betona. Kiev: "Budivelʹnyk", 1986.

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Malhotra, Ashok. Brick veneer concrete masonry unit backing. Ottawa: Canada Mortgage and Housing Corporation, 1997.

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I͡Akovlev, Anatoliĭ Ivanovich. Raschet ognestoĭkosti stroitelʹnykh konstrukt͡siĭ. Moskva: Stroĭizdat, 1988.

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Evans, D. J. Thermal movements in a multi-storey car park. London: Cement and Concrete Association, 1986.

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Частини книг з теми "Concrete slabs Thermal properties"

Wyrzykowski, Mateusz, Agnieszka Knoppik, Wilson R. Leal da Silva, Pietro Lura, Tulio Honorio, Yunus Ballim, Brice Delsaute, Stéphanie Staquet, and Miguel Azenha. "Thermal Properties." In Thermal Cracking of Massive Concrete Structures, 47–67. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-76617-1_3.

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McNamee, Robert Jansson, Pierre Pimienta, and Roberto Felicetti. "Thermal Properties." In Physical Properties and Behaviour of High-Performance Concrete at High Temperature, 61–69. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95432-5_4.

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Niaki, Mostafa Hassani, and Morteza Ghorbanzadeh Ahangari. "Thermal Properties of Polymer Concrete." In Polymer Concretes, 121–32. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003326311-7.

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Benboudjema, Farid, Jérôme Carette, Brice Delsaute, Tulio Honorio de Faria, Agnieszka Knoppik, Laurie Lacarrière, Anne Neiry de Mendonça Lopes, Pierre Rossi, and Stéphanie Staquet. "Mechanical Properties." In Thermal Cracking of Massive Concrete Structures, 69–114. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-76617-1_4.

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Wagh, Chandrashekhar D., Gandhi Indu Siva Ranjani, and Abhishek Kamisetty. "Thermal Properties of Foamed Concrete: A Review." In RILEM Bookseries, 113–37. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51485-3_9.

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Sun, Xiu Shan, Ying Hua Liu, Zhang Zhi Cen, and Dong Ping Fang. "Numerical Simulation of Deformation and Strength of Reinforced Concrete Slabs under Thermal-Mechanical Loads." In Key Engineering Materials, 2676–80. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.2676.

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Beddu, Salmia, Amalina Basri, Daud Mohamad, Nur Liyana Mohd Kamal, Nur Farhana, Zakaria Che Muda, Zarina Itam, Sivakumar Naganathan, Siti Asmahani Saad, and Teh Sabariah. "Thermal Properties of Concrete Containing Cenosphere and Phase Change Materials." In Lecture Notes in Civil Engineering, 143–54. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-5041-3_10.

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Abd-Elaal, E., S. A. Al-Bataineh, J. E. Mills, J. Whittle, and Y. Zhuge. "Enhancing Mechanical Properties of Rubberised Concrete With Non-thermal Plasma Treatment." In Lecture Notes in Civil Engineering, 23–32. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7603-0_3.

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Arkulis, Mikhail, Gennadii Dubskiy, Oxana Logunova, Galina Trubitsina, and Georgy Tokmazov. "Results of Measuring the Thermal Concrete Properties by the Impulse Method." In Lecture Notes in Civil Engineering, 109–16. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-83917-8_10.

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Wisner, Gregor, Frauke Bunzel, Steffen Sydow, Elisabeth Stammen, and Klaus Dilger. "Wood Foam and Textile Reinforced Concrete in Sandwich Elements and Self-Supporting Modules to Modernize Intermediate Ceilings in Old-Building Renovation." In Performance, Properties, and Resiliency of Thermal Insulations, 76–93. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2021. http://dx.doi.org/10.1520/stp162920200008.

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Тези доповідей конференцій з теми "Concrete slabs Thermal properties"

Leonard, Suzanne M., Brett C. Ramirez, and Sara E. Weyer. "Thermal Properties of Concrete Slats During Preheating of Empty Swine Facilities." In 2021 ASABE Annual International Virtual Meeting, July 12-16, 2021. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2021. http://dx.doi.org/10.13031/aim.202100241.

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Da Costa Santos, Ana Caroline, and Paul Archbold. "Mechanical Properties and Fracture Energy of Concrete Beams Reinforced with Basalt Fibres." In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.316.

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Fibre-reinforced concrete (FRC) is widely employed in the construction industry, with assorted fibre types being used for different applications. Typically, steel fibres give additional tensile strength to the mixture, while flexible fibres may be used in large sections, such as floor slabs, to control crack width and to improve the handling ability of precast sections. For many reasons, including durability concerns, environmental impact, thermal performance, etc, alternatives to the currently available fibres are being sought. This study examines the potential of using basalt fibres, a mineral and natural material, as reinforcement of concrete sections in comparison to steel fibres and plain concrete mix. Mixes were tested containing 0.5% and 1.0% of basalt fibres measuring 25mm length, 0.5% of the same material with 48mm length and steel fibres measuring 50mm by 0.05%, 0.1%, 0.15% and 0.2% of the concrete volume. For the mechanical performance analysis, the 3-point bending test was led and the fracture energy, Young’s modulus and tensile strength in different moments of the tests were calculated. When compared to the control mixtures and the steel-fibre-reinforced concrete, the mixes containing basalt had a reduction in their elastic modulus, representing a decrease in the concrete brittleness. At the same time, the fracture energy of the mixtures was significantly increased with the basalt fibres in both lengths. Finally, the flexural strength was also higher for the natural fibre reinforced concrete than for the plain concrete and comparable to the results obtained with the addition of steel fibres by 0.15%.

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Audouin, Marie, Nicolas Philippe, Fabien Bernardeau, Mariann Chaussy, Sergio Pons Ribera, Patricia Bredy Tuffe, Antoine Gasparutto, Florian Chalencon, Laetitia Bessette, and Pierre Bono. "Substitution of Synthetic Fibers by Bio-Based Fibers in a Structural Mortar." In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.472.

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The use of bio-based material is now widespread in insulation concrete, for example hemp concrete. The bio-based materials in concrete provide many advantages: lightness, sound and thermal insulation, hydrothermal regulation while contributing to a reduction in the environmental impact due to the carbon capture during the plant growth. The development of materials incorporating plant is therefore an important objective for the construction. The next step will be to introduce bio-based materials in structural mortars and concretes. The project FIBRABETON proposes to substitute synthetic or metallic fibers by natural fibers in screed and slab. After a selection of biomass on the resources availability, separation and fractionation are the key step in processing to obtain technical natural fibers. Bulk fiber shaping and packaging methods for easy handling and transportation are tested. Then, functionalization of technical natural fibers by physical & chemical treatments to improve the durability with cement paste is carried out. The second step concerns the introduction of treated or not treated fibers in mortar and concrete formulations. The variation of the nature of the biomass, fibers shape and dosage in concrete are studied. The workability, the compressive strength and withdrawal resistance are measured in order to obtain the best formulation parameters. The evolution of properties over time is also evaluated. The project FIBRABETON is carried out with ESTP, FRD and Vicat and is subsidized by ADEME, Grand Est region and FEDER.

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Sa´nchez, Mauricio A., William H. Sutton, and Carlos A. Sa´nchez. "Simulations of Thermal Performance for One- and Two-Dimensional Insulation and Aluminum Foil Fire Barriers." In 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49265.

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Nonbearing walls made of concrete frequently include one or two-dimensional gaps between sections to allow the concrete exert expansion or contraction due to temperature transients. These section gaps require the use of a thermal fire barrier to stop a fire from spreading during a period of time. In some applications, such as seismic structures, fire barriers are large and form substructures and partial enclosures. These type of fire barriers are often manufactured by layering alternating blankets of ceramic fiber insulation with bounding thin metallic foil sheets. In this case, the barrier must meet the specifications and effectiveness given by the ASTM standard E-119. This effectiveness is determined by the requirement of maintaining structural integrity by allowing some heat release while not permitting the fire flame to pass through. Little data is available on the thermal interaction of 2-D corners and splicing the layers for large barriers. It is expected that spatial and angular effects might either degrade performance or even cause “hot spots” in a barrier wall. Therefore, a numerical simulation of the barrier is accomplished by utilizing the spectral/gray and directional/modeled data of each one of the components and by taking into account two common geometrical building shapes. This simulation analysis is done by coupling of the discrete ordinates method in radiation heat transfer and the energy equation to previously published thermophysical experimental data used as a validation of the properties for fire barrier materials. Some of the effects of directional and surface properties and radiative heat transfer in fire barrier materials have been included in the numerical model. The Fluent®-based numerical model is able to match thermal performance of previous test systems. Initial calculations suggest that a fire barrier consisting of a 2D corner geometry exposed to a fire from either side would be thermally less robust than a slab of the same characteristic aspect ratio. This approximation has shown a preferential orientation for the barrier to be positioned when a fire or other high energy source is postulated.

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Gascon Alvarez, Eduardo, Caitlin T. Mueller, and Leslie K. Norford. "Dynamic thermal performance of structurally optimized concrete floor slabs." In 2021 Building Simulation Conference. KU Leuven, 2021. http://dx.doi.org/10.26868/25222708.2021.31052.

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"Early-Age Thermal Cracking in Laser-Screeded Concrete Slabs." In SP-204: Design and Construction Practices to Mitigate Cracking. American Concrete Institute, 2001. http://dx.doi.org/10.14359/10813.

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MARZOUK, H., U. A. EBEAD, and K. W. NEALE. "TENSILE PROPERTIES OF CONCRETE IN FRP-STRENGTHENED TWO-WAY SLABS." In Proceedings of the Sixth International Symposium on FRP Reinforcement for Concrete Structures (FRPRCS–6). World Scientific Publishing Company, 2003. http://dx.doi.org/10.1142/9789812704863_0040.

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""Effects of Size, Geometry and Material Properties on Punching Shear Resistance"." In SP-232: Punching Shear in Reinforced Concrete Slabs. American Concrete Institute, 2005. http://dx.doi.org/10.14359/14935.

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Li, Jx, Sw Lin, Cj Yang, Ln Liu, B. Chen, Xf Wang, Y. Bai, F. Zhang, Fw Ning, and Ll Lv. "Preparation and properties of bendable concrete for bridge-deck link slabs." In 2021 7th International Conference on Hydraulic and Civil Engineering & Smart Water Conservancy and Intelligent Disaster Reduction Forum (ICHCE & SWIDR). IEEE, 2021. http://dx.doi.org/10.1109/ichceswidr54323.2021.9656306.

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Seng, Billy, Camille Magniont, Sandra Spagnol, and Sylvie Lorente. "Evaluation of Hemp Concrete Thermal Properties." In 2016 Intl IEEE Conferences on Ubiquitous Intelligence & Computing, Advanced and Trusted Computing, Scalable Computing and Communications, Cloud and Big Data Computing, Internet of People, and Smart World Congress (UIC/ATC/ScalCom/CBDCom/IoP/SmartWorld). IEEE, 2016. http://dx.doi.org/10.1109/uic-atc-scalcom-cbdcom-iop-smartworld.2016.0154.

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Baral, Aniruddha, Jeffery Roesler, and Junryu Fu. Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2. Illinois Center for Transportation, September 2021. http://dx.doi.org/10.36501/0197-9191/21-031.

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High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.

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Roberson, Madeleine, Kathleen Inman, Ashley Carey, Isaac Howard, and Jameson Shannon. Probabilistic neural networks that predict compressive strength of high strength concrete in mass placements using thermal history. Engineer Research and Development Center (U.S.), June 2022. http://dx.doi.org/10.21079/11681/44483.

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This study explored the use of artificial neural networks to predict UHPC compressive strengths given thermal history and key mix components. The model developed herein employs Bayesian variational inference using Monte Carlo dropout to convey prediction uncertainty using 735 datapoints on seven UHPC mixtures collected using a variety of techniques. Datapoints contained a measured compressive strength along with three curing inputs (specimen maturity, maximum temperature experienced during curing, time of maximum temperature) and five mixture inputs to distinguish each UHPC mixture (cement type, silicon dioxide content, mix type, water to cementitious material ratio, and admixture dosage rate). Input analysis concluded that predictions were more sensitive to curing inputs than mixture inputs. On average, 8.2% of experimental results in the final model fell outside of the predicted range with 67.9%of these cases conservatively underpredicting. The results support that this model methodology is able to make sufficient probabilistic predictions within the scope of the provided dataset but is not for extrapolating beyond the training data. In addition, the model was vetted using various datasets obtained from literature to assess its versatility. Overall this model is a promising advancement towards predicting mechanical properties of high strength concrete with known uncertainties.

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Baral, Aniruddha, Jeffrey Roesler, M. Ley, Shinhyu Kang, Loren Emerson, Zane Lloyd, Braden Boyd, and Marllon Cook. High-volume Fly Ash Concrete for Pavements Findings: Volume 1. Illinois Center for Transportation, September 2021. http://dx.doi.org/10.36501/0197-9191/21-030.

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High-volume fly ash concrete (HVFAC) has improved durability and sustainability properties at a lower cost than conventional concrete, but its early-age properties like strength gain, setting time, and air entrainment can present challenges for application to concrete pavements. This research report helps with the implementation of HVFAC for pavement applications by providing guidelines for HVFAC mix design, testing protocols, and new tools for better quality control of HVFAC properties. Calorimeter tests were performed to evaluate the effects of fly ash sources, cement–fly ash interactions, chemical admixtures, and limestone replacement on the setting times and hydration reaction of HVFAC. To better target the initial air-entraining agent dosage for HVFAC, a calibration curve between air-entraining dosage for achieving 6% air content and fly ash foam index test has been developed. Further, a digital foam index test was developed to make this test more consistent across different labs and operators. For a more rapid prediction of hardened HVFAC properties, such as compressive strength, resistivity, and diffusion coefficient, an oxide-based particle model was developed. An HVFAC field test section was also constructed to demonstrate the implementation of a noncontact ultrasonic device for determining the final set time and ideal time to initiate saw cutting. Additionally, a maturity method was successfully implemented that estimates the in-place compressive strength of HVFAC through wireless thermal sensors. An HVFAC mix design procedure using the tools developed in this project such as the calorimeter test, foam index test, and particle-based model was proposed to assist engineers in implementing HVFAC pavements.

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Gungor, Osman, Imad Al-Qadi, and Navneet Garg. Pavement Data Analytics for Collected Sensor Data. Illinois Center for Transportation, October 2021. http://dx.doi.org/10.36501/0197-9191/21-034.

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The Federal Aviation Administration instrumented four concrete slabs of a taxiway at the John F. Kennedy International Airport to collect pavement responses under aircraft and environmental loading. The study started with developing preprocessing scripts to organize, structure, and clean the collected data. As a result of the preprocessing step, the data became easier and more intuitive for pavement engineers and researchers to transform and process. After the data were cleaned and organized, they were used to develop two prediction models. The first prediction model employs a Bayesian calibration framework to estimate the unknown material parameters of the concrete pavement. Additionally, the posterior distributions resulting from the calibration process served as a sensitivity analysis by reporting the significance of each parameter for temperature distribution. The second prediction model utilized a machine-learning (ML) algorithm to predict pavement responses under aircraft and environmental loadings. The results demonstrated that ML can predict the responses with high accuracy at a low computational cost. This project highlighted the potential of using ML for future pavement design guidelines as more instrumentation data from future projects are collected to incorporate various material properties and pavement structures.

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Wei, Fulu, Ce Wang, Xiangxi Tian, Shuo Li, and Jie Shan. Investigation of Durability and Performance of High Friction Surface Treatment. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317281.

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The Indiana Department of Transportation (INDOT) completed a total of 25 high friction surface treatment (HFST) projects across the state in 2018. This research study attempted to investigate the durability and performance of HFST in terms of its HFST-pavement system integrity and surface friction performance. Laboratory tests were conducted to determine the physical and mechanical properties of epoxy-bauxite mortar. Field inspections were carried out to identify site conditions and common early HFST distresses. Cyclic loading test and finite element method (FEM) analysis were performed to evaluate the bonding strength between HFST and existing pavement, in particular chip seal with different pretreatments such as vacuum sweeping, shotblasting, and scarification milling. Both surface friction and texture tests were undertaken periodically (generally once every 6 months) to evaluate the surface friction performance of HFST. Crash records over a 5-year period, i.e., 3 years before installation and 2 years after installation, were examined to determine the safety performance of HFST, crash modification factor (CMF) in particular. It was found that HFST epoxy-bauxite mortar has a coefficient of thermal expansion (CTE) significantly higher than those of hot mix asphalt (HMA) mixtures and Portland cement concrete (PCC), and good cracking resistance. The most common early HFST distresses in Indiana are reflective cracking, surface wrinkling, aggregate loss, and delamination. Vacuum sweeping is the optimal method for pretreating existing pavements, chip seal in particular. Chip seal in good condition is structurally capable of providing a sound base for HFST. On two-lane highway curves, HFST is capable of reducing the total vehicle crash by 30%, injury crash by 50%, and wet weather crash by 44%, and providing a CMF of 0.584 in Indiana. Great variability may arise in the results of friction tests on horizontal curves by the use of locked wheel skid tester (LWST) due both to the nature of vehicle dynamics and to the operation of test vehicle. Texture testing, however, is capable of providing continuous texture measurements that can be used to calculate a texture height parameter, i.e., mean profile depth (MPD), not only for evaluating friction performance but also implementing quality control (QC) and quality assurance (QA) plans for HFST.

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PERFORMANCE OF STUD SHEAR CONNECTIONS IN COMPOSITE SLABS WITH VARIOUS CONFIGURATIONS (ICASS’2020). The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.351.

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This research project aims to examine the structural behaviour of stud shear connections with both solid concrete slabs and composite slabs under standard and modified push-out tests. A total of 27 push-out tests were carried out to provide test data of typical stud shear connections. It should be noted that the modified push-out tests were proposed in which the stud shear connections were subjected to combined shear and pull-out forces. Advanced finite element models using ABAQUS have also been established and calibrated carefully against the test data. Systematic numerical investigations are conducted to provide new understandings on load transfer mechanisms of these stud shear connections. Moreover, a comprehensive parametric study is carried out using various material properties of the concrete and various geometry of the profiled steel decking. A configuration parameter ηd and a reduction factor ηt are proposed for use in conjunction with the reduction factor kd given in EN 1994-1- 1 to incorporate the effects of installation positions of headed shear stud, trough widths of profiled decks, and presence of significant pull-out forces.

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FINITE ELEMENT SIMULATION FOR ULTRA-HIGH-PERFORMANCE CONCRETE-FILLED DOUBLE-SKIN TUBES EXPOSED TO FIRE. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.263.

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Анотація:

Ultra-high-performance concrete (UHPC) or ultra-high-strength concrete (UHSC) are alternatively used to reduce construction materials, thereby achieving more sustainable constructions. Moreover, engaging the advantages of concrete cores and outer steel tubes in concrete-filled steel tubes (CFST) or ductile concrete-filled double-skin tubes (CFDST) is of great interest for the better performance of such members under fire. Nevertheless, current design provisions do not provide design models for UHPC-filled double-skin tubes under fire, and existing finite-element (FE) methodologies available in the literature may not accurately simulate the behaviour of CFDST exposed to fire. Therefore, this paper develops a comprehensive FE protocol implementing the scripting technique to model CFDST members for heat transfer and coupled (simultaneously or sequentially) thermal-stress analyses. Various modelling parameters incorporated in the proposed FE routine include the cross-sectional geometry (circular, elliptical, hexagonal, octagonal, and rectangular), the size (width, diameter, and wall thickness), interactions, meshing, thermal- and mechanical-material properties, and boundary conditions. The detailed algorithm for heat transfer analysis is presented and elaborated via a flow chart. Validations, verifications, and robustness of the developed FE models are established based on extensive comparison studies with existing fire tests available in the literature. As a result, and to recognize the value of the current FE methodology, an extensive parametric study is conducted for different affecting parameters (e.g., nominal steel ratio, hollowness ratio, concrete cylindrical strength, yield strength of metal tubes, and width-to-thickness ratio). Extensive FE results are used for optimizing the fire design of such members. Consequently, a simplified and accurate analytical model that can provide the axial load capacity of CFDST columns under different fire ratings is presented

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