Articoli di riviste: "Concrete Ageing"

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Van Breugel, K., e T. A. Van Beek. "Ageing of old and modern concrete structures – Observations and research". Revista ALCONPAT 7, n. 1 (31 gennaio 2017): 57–72. http://dx.doi.org/10.21041/ra.v7i1.174.

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Ageing of old and modern concrete structures – Observations and researchABSTRACTAgeing is an inherent feature of nature. Yet it seems to be a rather new topic in both science and engineering. The main reason for increasing attention for ageing as a topic is the growing awareness that, particularly in industrialized countries, ageing of our assets is a financial burden for the society and affects the overall sustainability of our planet. In this contribution, the urgency and challenges of ageing of concrete structures are addressed. The complexity of ageing problems will be illustrated by looking in more detail to the evolution in concrete mix design and the consequences thereof for the long-term performance of concrete structures. Emphasis will be on ageing of concrete infrastructure and justification of research on ageing phenomena.Keywords: infrastructure; sustainability; ageing; mix design; autogenous shrinkage; codes. Envejecimiento de antiguas y modernas estructuras de concreto - Observaciones e investigacionesRESUMENEl envejecimiento es una característica inherente de la naturaleza. Sin embargo, parece ser un tema bastante nuevo en la ciencia y la ingeniería. La principal razón para aumentar la atención por el envejecimiento como tema es la creciente conciencia de que, en particular en los países industrializados, el envejecimiento de nuestros activos es una carga financiera para la sociedad y afecta la sostenibilidad global de nuestro planeta. En esta contribución se abordan la urgencia y los desafíos del envejecimiento de las estructuras de concreto. La complejidad de los problemas de envejecimiento se ilustra examinando con más detalle la evolución del diseño de la mezcla de concreto y sus consecuencias para el rendimiento a largo plazo de las estructuras de concreto. Se hace hincapié en el envejecimiento de las infraestructuras de concreto y en la justificación de la investigación sobre fenómenos de envejecimiento.Palabras clave: infraestructura; sostenibilidad; envejecimiento; mezcla de diseño; contracción autógena; códigos. Envelhecimento estruturas de betão antigos e modernos - Observações e pesquisaRESUMOO envelhecimento é uma característica inerente à natureza. No entanto, parece ser um bastante novo tópico em ciência e engenharia. A principal razão para uma maior atenção por tema envelhecimento é a consciência crescente de que, particularmente nos países industrializados, o envelhecimento dos nossos ativos é um encargo financeiro para a sociedade e afeta a sustentabilidade global do nosso planeta. Nesta contribuição a urgência e os desafios de estruturas de concreto envelhecimento são abordados. A complexidade dos problemas de envelhecimento está ilustrada em mais pormenor através da análise da evolução do desenho da mistura de betão e o seu impacto sobre o desempenho a longo prazo das estruturas de betão. A ênfase é colocada na infra-estrutura de envelhecimento do concreto e justificação da pesquisa sobre os fenómenos de envelhecimento.Palavras-chave: infra-estrutura; sustentabilidade; envelhecimento; misture projeto; retração autógena; códigos.

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Bamforth, P. B., e W. F. Price. "The Long-Term Properties of Concrete Used in Prestressed Concrete Pressure Vessels". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 208, n. 2 (maggio 1994): 123–34. http://dx.doi.org/10.1243/pime_proc_1994_208_021_02.

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Data are presented on the late-life properties of concretes used in prestressed concrete pressure vessels (PCPV) and containment structures. The effects of ageing under simulated PCPV conditions are discussed.

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MOCEIKIS, Rimvydas, Asta KIČAITĖ, Gintautas SKRIPKIŪNAS e Aleksandrs KORJAKINS. "AGEING MODELS AND ACCELERATED AGEING TESTS OF GLASS FIBER REINFORCED CONCRETE". Engineering Structures and Technologies 10, n. 1 (27 aprile 2018): 10–17. http://dx.doi.org/10.3846/est.2018.1467.

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Glass fiber reinforced concrete (GRC) is used for 40 years to create world’s most stunning and complex architectural elements due to its high mechanical properties, particularly flexural strength. Yet it is very important to note that any type of glass fibers in the concrete matrix are undergoing complex ageing processes, resulting to significant decrease of initial mechanical characteristics of this composite material under natural weathering conditions. Aspects of GRC durability are mainly dependent from the properties of fibers and interaction between them and concrete matrix. In this article, long term strength retention of this composite material is discussed, existing experimental data of weathering tests presented, and main corrosion mechanisms explained. Lack of knowledge about freeze- thaw resistance of glass fiber reinforced concrete is addressed. Finally, latest attempts of GRC durability improvement are reviewed, such as adding micro fillers, polymers to the concrete matrix and enhancing surface of fibers in Nano scale.

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Yu, Xin, Quantao Liu, Pei Wan, Jiangkai Song, Huan Wang, Feiyang Zhao, Yafei Wang e Jinyi Wu. "Effect of Ageing on Self-Healing Properties of Asphalt Concrete Containing Calcium Alginate/Attapulgite Composite Capsules". Materials 15, n. 4 (14 febbraio 2022): 1414. http://dx.doi.org/10.3390/ma15041414.

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Calcium alginate capsules within asphalt concrete can gradually release interior asphalt rejuvenator under cyclic loading to repair micro cracks and rejuvenate aged asphalt in-situ. However, asphalt pavement will become aged due to environmental and traffic factors during the service period. In view of this, this paper investigated the effect of ageing on the healing properties of asphalt concrete containing calcium alginate/attapulgite composite capsules under cyclic loading. The capsules were fabricated using the orifice-bath method and the morphological structure, mechanical strength, thermal stability, oil release ratios and healing levels of capsules in fresh, short-term ageing and long-term ageing asphalt concrete were explored. The results indicated that the different ageing treatments would not damage the multi-chamber structure nor decrease the mechanical strength of capsules but would induce the capsules release oil prematurely. The premature oil released from capsules in turn can offset the ageing effect owing to ageing treatment. The short-term ageing and long-term ageing plain asphalt mixtures gained strength recovery ratios of 39.3% and 34.2% after 64,000 cycles of compression loading, while the strength recovery ratios of short-term ageing and long-term ageing asphalt mixtures containing capsules were 63.5% and 54.8%, respectively.

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Xu, Shi, Xueyan Liu, Amir Tabaković e Erik Schlangen. "The influence of asphalt ageing on induction healing effect on porous asphalt concrete". RILEM Technical Letters 3 (18 febbraio 2019): 98–103. http://dx.doi.org/10.21809/rilemtechlett.2018.74.

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Induction healing is a proven technology which is able to improve the self-healing capacity of asphalt concrete. Healing is achieved via electromagnetic current produced by passing induction machine, where steel asphalt constituents heat up which in turn soften the bitumen in the asphalt layer, allowing it to flow and close cracks, repairing the damage. This paper reports on the study which investigated the influence of ageing on the healing capacity of Porous Asphalt (PA) concrete. Porous Asphalt concrete mix was prepared first, then subjected to an accelerated (laboratory) ageing process using a ventilated oven. In order to further evaluate the induction healing efficiency of asphalt concrete, Semi-circular bending (SCB) and healing cycles were performed on asphalt concrete specimens. The results show that with an increase of the ageing level of porous asphalt concrete, the induction healing efficiency decreases.

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Kucharczyková, Barbara, Petr Daněk, Dalibor Kocáb e Petr Misák. "Experimental Analysis on Shrinkage and Swelling in Ordinary Concrete". Advances in Materials Science and Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/3027301.

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The paper deals with the experimental determination of shrinkage development during concrete ageing. Three concrete mixtures were made. They differed in the amount of cement in the fresh mixture, 300, 350, and 400 kg/m3. In order to determine the influence of plasticiser on the progress of volume changes, another three concrete mixtures were prepared with plasticiser in the amount of 0.25% by cement mass. Measurements were performed with the goal of observing the influence of cement and plasticiser content on the overall development of volume changes in the concrete. Changes in length and mass losses of the concrete during ageing were measured simultaneously. The continuous measurement of concrete mass losses caused by drying of the specimen’s surface proved useful during the interpretation of results obtained from the concrete shrinkage measurement. During the first 24 hours of ageing, all the concrete mixtures exhibited swelling. Its magnitude and progress were influenced by cement, water, and plasticiser content. However, a loss of mass caused by water evaporation from the surface of the specimens was also recorded in this stage. The measured progress of shrinkage corresponded well to the progress of mass loss.

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Hall, Jon G. "AI Spots Crumbling Concrete". ITNOW 66, n. 1 (15 febbraio 2024): 28–29. http://dx.doi.org/10.1093/itnow/bwae014.

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BURMAN, A., D. MAITY, S. SREEDEEP e I. GOGOI. "LONG-TERM INFLUENCE OF CONCRETE DEGRADATION ON DAM–FOUNDATION INTERACTION". International Journal of Computational Methods 08, n. 03 (settembre 2011): 397–423. http://dx.doi.org/10.1142/s0219876211002472.

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The dam–foundation interaction behavior under the application of seismic load has been investigated in the present paper using finite element technique in the time domain. Since the dam face is in constant contact with water, concrete degradation due to hygromechanical loading is inevitable and should be considered in the analysis procedure. This ageing process of concrete leads to loss of stiffness and strength of the material. Therefore, to assess the behavior of the dam at a later stage of its life, it is important to determine the proper strength of the concrete at a certain age. An approach to include the time-dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic degradation index is presented. An iterative scheme has been developed to model the dam–foundation interaction effects of the coupled system. The strains and the displacements are observed to increase if the ageing procedure of the gravity dam is taken into account. The long-term behavior of the aged concrete gravity and foundation interaction has been observed by using a developed ageing model for concrete.

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Radziszewski, Piotr. "MODIFIED ASPHALT MIXTURES RESISTANCE TO PERMANENT DEFORMATIONS". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, n. 4 (31 dicembre 2007): 307–15. http://dx.doi.org/10.3846/13923730.2007.9636451.

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Permanent deformations, primarily in the form of ruts, are one of the basic asphalt pavement damages impairing its service properties. Application of appropriate asphalt mixtures and binder modification are effective methods for improving asphalt courses resistance. While being manufactured, stored, fitted into a road pavement and during long term service, bitumen binders and asphalt mixtures are subject to continuous unfavourable ageing processes during which pavement courses characteristics change considerably, resistance to permanent deformations being among them. This article presents rut and dynamic creep test results of concrete, SMA (stone mastic asphalt), MNU (thin courses of non‐continuous grain mixtures), Superpave mixture and porous asphalt mixture of two air void content percentages: 15 %, 20 %. Asphalt concrete mixtures, MNU's and porous asphalt mixtures contained elastomer, plastomer and fine rubber modified binders. Samples for laboratory rut tests were made by slab compaction because this method, as the author's previous research had shown, was the closest to ‘in‐situ’ conditions. Resistance to permanent deformations of the examined specimens was evaluated before aging, after technological aging (short term ageing) and after service ageing (long‐term ageing). The test results show that resistance to permanent deformations depends on the kind of asphalt mixture and binder applied. Concrete asphalts with fine rubber modified bitumens and concrete asphalts with 7 % polymer modified binders as well as SMA's and Superpave mixtures with unmodified binders appeared to be most resistant to permanent deformations after a long‐term laboratory ageing. It was proved that the overall evaluation of resistance to permanent deformations could be obtained by rut and creep testing of asphalt mixtures exposed to short‐ and long‐term ageing. Simultaneous determining 4 parameters: maximum rut depth after short‐term ageing, rutting coefficient after operational ageing, stiffness creeping modulus after long‐term ageing and cumulated deformation after short‐term ageing, facilitates full characteristics of modified asphalt mixes designed to be built in the wearing course of a road pavement.

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Sistonen, Esko, Fahim Al-Neshawy e Miguel Ferreira. "Ageing Management Platform For NPP Concrete Structures". IABSE Symposium Report 103, n. 1 (11 febbraio 2015): 280–87. http://dx.doi.org/10.2749/222137815815622942.

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Hanna, S., e R. Jones. "Composite wraps for ageing infrastructure: concrete columns". Composite Structures 38, n. 1-4 (maggio 1997): 57–64. http://dx.doi.org/10.1016/s0263-8223(97)00041-x.

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Dunster, Andrew, e Ian Holton. "Assessment of ageing high alumina cement concrete". Structural Survey 18, n. 1 (marzo 2000): 16–21. http://dx.doi.org/10.1108/02630800010322454.

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Alasali, Bader Eddin, e Srinivasa Reddy N. "Ageing Behavior Analysis of Concrete Tunnel Lining". International Journal of Civil Engineering 9, n. 11 (30 novembre 2022): 43–49. http://dx.doi.org/10.14445/23488352/ijce-v9i11p106.

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Radziszewski, Piotr, Robert Ziolkowski e Donatas Čygas. "TECHNOLOGICAL AGEING INFLUENCE ON VISCOSITY OF SELECTED BITUMENS". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 9, n. 1 (31 marzo 2003): 20–24. http://dx.doi.org/10.3846/13923730.2003.10531297.

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The article presents one of the main parameters of bitumens used for asphalt concrete mixtures production—viscosity. The authors analyse technological ageing process and its influence on viscosity of selected bitumens. Dependence of the viscosity of bitumens on type and amount of the additives, temperature and ageing is described through experiments. Research findings show that the employment of different types of additives increases bitumen viscosity and positively effect the bitumen ageing resistance. Practical application of presented conclusions and recommendations will enable to improve the main characteristics of asphalt concrete pavements and traffic conditions on roads.

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Jamshaid, Hafsa, Husnain Ali, Rajesh Kumar Mishra, Shabnam Nazari e Vijay Chandan. "Durability and Accelerated Ageing of Natural Fibers in Concrete as a Sustainable Construction Material". Materials 16, n. 21 (27 ottobre 2023): 6905. http://dx.doi.org/10.3390/ma16216905.

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This paper presents an experimental study on the influence of alkaline environments on natural fibers of plant and mineral origin in concretes. The durability of concrete-based composite materials is influenced by the properties of the reinforcing fiber, and the serviceability of concrete is dependent on its durability. The aim of the present study is to investigate the strength, weight loss %, and surface degradation of jute, sugarcane, coconut, sisal, as well as basalt fibers through an accelerated aging method when used as reinforcements in concrete. The samples were immersed in an alkaline environment of sodium and calcium hydroxide at two different levels of pH for one week. Further, the fibers were immersed in NaOH and Ca(OH)2 solutions of 1 M, 2 M, 4 M, and 6 M concentrations for 48 h in order to investigate the gradual effect of an alkaline environment on the mechanical properties of the fiber. It was concluded that the weight loss % was greatest for jute fibers when used in concrete composite, while there was no significant effect on the basalt fiber samples. The strength of jute fiber in the concrete sample was also most severely affected by the aging process, compared to other fibers. The strength of basalt fibers in a concrete composite was least affected by the aging process. In some cases, the sisal fiber sample showed an increase in fiber tenacity after the aging process due to fibrillation, which might have increased the interfacial area. The fiber microstructure before and after the aging was evaluated through the use of scanning electron microscopy (SEM). SEM analyses of different fibers were carried out to investigate surface degradation. The fiber pull-out strength was found to be the greatest for basalt fiber, followed by jute and sisal. This is indicative of the excellent adhesion of such fibers with cement in a concrete composite. In these cases, the use of sisal fiber results in defibrillation and increased specific surface area. Sugarcane and coconut fibers ruptured due to their inherent weakness and provided only a small increment in the mechanical performance of the concrete. Basalt fiber-reinforced concrete offered the greatest compressive strength, followed by jute and sisal. These observations provide crucial information regarding the durability and aging of natural fiber-reinforced concrete.

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Osburg, Andrea, Alexander Gypser e Martin Ulrich. "Development of Polymer Concrete with Non-Standardised Fillers for Innovative Building Materials". Advanced Materials Research 1129 (novembre 2015): 484–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1129.484.

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The use of polymer concrete in building construction is a relatively new application. A building block system (Modular Assembly System: MAS-System) and the mobile fabrication technology for the reversible construction of buildings with regionally available aggregates, were developed in a project of applied research. The aspects of the successful material development are described, especially with regard to the characterisation of both the binders and the polymer concretes, considering strength and durability. The polymer concrete consists approximately of 90 % fillers, 10 % polymer binder and additives. The investigation of the binder-system included the determination of gel time and temperature development, shrinkage, wetting of formwork materials and immersion tests with marine water. The aim was an adaptation and optimisation of the binder system. The characterisation of mechanical properties of the polymer concrete was realised by determining its strength in a temperature range between - 40 °C and 60 °C. Compression tests on wall segments were also realised. Ageing is an important aspect of the durability of polymer bonded materials. Special tests were used for an accelerated ageing, including impacts of temperature change, cold rain water and natural radiation.

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Ding, Yuqing, e Shahzma Jaffer. "DEVELOPMENT OF FINITE ELEMENT MODELS FOR THE STUDY OF AGEING EFFECTS IN CANDU 6 CONCRETE CONTAINMENT BUILDINGS". CNL Nuclear Review 5, n. 1 (giugno 2016): 37–48. http://dx.doi.org/10.12943/cnr.2015.00060.

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In nuclear power plants (NPPs), concrete containment buildings (CCBs) provide the final physical barrier against the release of radioactive materials into the environment and protect the nuclear structures housed within the containment building. CCBs have to be maintained to ensure leak tightness and sound structural integrity for the safe operation throughout the life of NPPs. However, the integrity of CCBs may be affected by the ageing of its concrete, post-tensioning cables and reinforcing bars (rebars). Finite element models (FEMs) of CANDU 6 CCBs have been developed using 2 independent finite element programs for the study of the effect of ageing of CCBs. These FEMs have been validated using multiple-source data and have been used for preliminary analyses of the effect of thermal load and ageing degradation on the concrete structure. The modelling assumptions and simplifications, approach, and validation are discussed in this paper. The preliminary analyses for temperature effects and potential applications to the study of ageing degradation in CCBs using the FEMs are briefly introduced.

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Josserand, Laurent, Olivier Coussy e François de Larrard. "Bleeding of concrete as an ageing consolidation process". Cement and Concrete Research 36, n. 9 (settembre 2006): 1603–8. http://dx.doi.org/10.1016/j.cemconres.2004.10.006.

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Gu, Chongshi, Xinran Cui, Hao Gu e Meng Yang. "A New Hybrid Monitoring Model for Displacement of the Concrete Dam". Sustainability 15, n. 12 (15 giugno 2023): 9609. http://dx.doi.org/10.3390/su15129609.

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For the structural health diagnostic of concrete dams, the mathematical monitoring model based on the measured deformation values is of great significance. The main purpose of this paper is to reconstruct the ageing component and the temperature component in the traditional Hydraulic-Seasonal-Time (HST) hybrid model by combining the measured values. On the one hand, a better mathematical model for the ageing displacement of concrete dams is proposed combined with the Burgers model to separate the instantaneous elastic hydraulic deformation and the hysteretic hydraulic deformation, and then it subsumes the latter into the ageing deformation to describe its reversible component. According to the Burgers model, the inverted elastic modulus of the Jinping-Ⅰ concrete dam is 46.5 GPa, which is closer to the true value compared with the HST model. On the other hand, the kernel principal component analysis (KPCA) method is used to extract the principal components of the dam thermometers for replacing the period harmonic thermal factor. A multiple linear regression (MLR) model is established to fit the measured displacement of the concrete arch dam and to verify the accuracy of the proposed hybrid model. The results show that the proposed model reaches higher accuracy than the traditional HST hybrid model and is helpful to improve the interpretation of the separated displacement components of the concrete dams.

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Alj, Ismail, Marc Quiertant, Aghiad Khadour, Quentin Grando e Karim Benzarti. "Environmental Durability of an Optical Fiber Cable Intended for Distributed Strain Measurements in Concrete Structures". Sensors 22, n. 1 (26 dicembre 2021): 141. http://dx.doi.org/10.3390/s22010141.

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The present study investigates the environmental durability of a distributed optical fiber sensing (DOFS) cable on the market, commonly used for distributed strain measurements in reinforced concrete structures. An extensive experimental program was conducted on different types of specimens (including samples of bare DOFS cable and plain concrete specimens instrumented with this DOFS cable) that were exposed to accelerated and natural ageing (NA) conditions for different periods of up to 18 months. The instrumentation of both concrete specimens consisted of DOFS cables embedded at the center of the specimens and bonded at the concrete surface, as these two configurations are commonly deployed in the field. In these configurations, the alkalinity of the surrounding cement medium and the outdoor conditions are the main factors potentially affecting the characteristics of the DOFS component materials and the integrity of the various interfaces, and hence impacting the strain transfer process between the host structure and the core optical fiber (OF). Therefore, immersion in an alkaline solution at an elevated temperature or freeze/thaw (F/T) and immersion/drying (I/D) cycles were chosen as accelerated ageing conditions, depending on the considered configuration. Mechanical characterizations by tensile and pull-out tests were then carried out on the exposed specimens to assess the evolution of the mechanical properties of individual component materials as well as the evolution of bond properties at various interfaces (internal interfaces of the DOFS cable, and interface between the cable and the host structure) during ageing. Complementary physico-chemical characterizations were also performed to better understand the underlying degradation processes. The experimental results highlight that immersion in the alkaline solution induced a significant and rapid decrease in the bond properties at internal interfaces of the DOFS cable and at the cable/concrete interface (in the case of the embedded cable configuration), which was assigned to chemical degradation at the surface of the cable coating in contact with the solution (hydrolysis and thermal degradation of the EVA copolymer component). Meanwhile, F/T and I/D cycles showed more limited effects on the mechanical properties of the component materials and interfaces in the case of the bonded cable configuration. A comparison with the same specimens exposed to outdoor NA suggested that the chosen accelerated ageing conditions may not be totally representative of actual service conditions, but provided indications for improving the ageing protocols in future research. In the last part, an analysis of the distributed strain profiles collected during pull-out tests on instrumented concrete specimens clearly illustrated the consequences of ageing processes on the strain response of the DOFS cable.

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Mumenya, S. W., R. B. Tait e M. G. Alexander. "Mechanical behaviour of Textile Concrete under accelerated ageing conditions". Cement and Concrete Composites 32, n. 8 (settembre 2010): 580–88. http://dx.doi.org/10.1016/j.cemconcomp.2010.07.007.

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Momtahan, A., R. P. Dhakal e A. Rieder. "Effects of strain-ageing on New Zealand reinforcing steel bars". Bulletin of the New Zealand Society for Earthquake Engineering 42, n. 3 (30 settembre 2009): 179–86. http://dx.doi.org/10.5459/bnzsee.42.3.179-186.

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Modern seismic design codes, which are based on capacity design concepts, allow formation of plastic hinges in specified locations of a structure. This requires reliable estimation of strength of different components so that the desired hierarchy of strength of the structural components can be ensured to guarantee the formation of plastic hinges in the ductile elements. As strength of longitudinal reinforcing bars governs the strength of reinforced concrete members, strain-ageing, which has significant effect on the strength of reinforcing bars, should be given due consideration in capacity design. Strain-ageing can increase the yield strength of reinforcing steel bars and hence the strength of previously formed plastic hinges, thereby likely to force an unfavourable mechanism (such as strong beam-weak column leading to column hinging) to take place in subsequent earthquakes. In this paper, the strain-ageing effect of commonly used New Zealand reinforcing steel bars is experimentally investigated. Common New Zealand steel reinforcing bars are tested for different levels of pre-strain and different time intervals up to 50 days, and the results are discussed focussing on the extent of strain-ageing and its possible implications on seismic design provisions. The results indicate that designers need to use a higher flexural strength (in addition to overstrength) for the weaker member in checking the strength hierarchy in capacity design of reinforced concrete frames. Similarly, in designing retrofit measures to restore a damaged reinforced concrete member engineers need to take into account an increase of yield strength of the reinforcing steel bars employed in the member due to the strain-ageing phenomenon and the extent of increase in the yield strength depends on the level of damage.

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Tang, Ning, Kaikai Yang, Wenhao Pan, Limei Wu, Qing Wang e Yanwen Chen. "Displacement Investigation of KNN-Bitumen-Based Piezoceramics in Asphalt Concrete". Advances in Materials Science and Engineering 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/1924753.

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Piezoelectric material has excellent characteristics of electromechanical coupling so that it could be widely applied in structural health monitoring field. Nondestructive testing of piezoelectric technique becomes a research focus on piezoelectric field. Asphalt concrete produces cumulative damage under the multiple repeated vehicle load and natural situation, so it is suited material and structure for nondestructive application. In this study, a test system was established by driving power of piezoceramic, laser displacement sensor, computer, and piezo-embedded asphalt concrete. Displacement, hysteresis, creeps, and dynamic behavior of KNN piezoceramic element embedded in asphalt concrete were tested. The results indicate that displacement output attained 0.4 μm to 0.7 μm when the loads were from 0 N to 150 N. The hysteresis was not obvious when the load was from 0 N to 100 N, aside from higher loads. The creep phenomenon can be divided into two parts: uptrend and balance. The more serious the asphalt binder ageing is, the larger the displacement is, when piezo-asphalt concrete has already been in serious ageing.

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Torres, Pablo Peña, Elhem Ghorbel e George Wardeh. "Towards a New Analytical Creep Model for Cement-Based Concrete Using Design Standards Approach". Buildings 11, n. 4 (9 aprile 2021): 155. http://dx.doi.org/10.3390/buildings11040155.

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Creep properties are determined in design standards by measuring the creep coefficient, noted φ, as a function of time, t, and the age of the concrete at loading, t0. The work aims to study the validity of the analytical models proposed in the most used international standards and to check the possibility of their extension to estimate the creep of recycled aggregates concrete (RAC). A database was built from experimental results available in bibliographic references including 121 creep curves divided into 73 curves for natural aggregates concrete (NAC) and 48 curves for RAC. The comparison between the experimental and predicted values showed a significant dispersion for NAC and RAC. For the remediation of this dispersion, a new analytical model was developed for NAC. The parameters being the conventional creep coefficient, φ0, the power of the ageing function, named α, and βh, which accounts for the relative humidity and the compressive strength in the ageing function, were identified by inverse analysis. It was found that the power of the ageing function is 0.44 and not 0.3, as fixed by Eurocode 2 (EC2). Moreover, new expressions were proposed for φ0 and βh. The presence of recycled aggregates was considered through the equivalent replacement ratio.

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Lucquiaud, V., L. Courard, O. Gérard, F. Michel, M. Handy, S. Aggoun e A. Cousture. "Evaluation of the Durability of Hydrophobic Treatments on Concrete Architectural Heritage". Restoration of Buildings and Monuments 20, n. 6 (1 dicembre 2014): 395–404. http://dx.doi.org/10.1515/rbm14.20.6-0038.

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Abstract The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products - mainly silane or siloxane in either water or solvent based formulations - were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions.

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Zvolánek, Lukáš, e Ivailo Terzijski. "Methods Considering the Concrete Creep due to Shrinkage". Solid State Phenomena 259 (maggio 2017): 3–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.259.3.

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Creep of concrete is a phenomenon that is not only significant in the long term, but also at young concrete. The paper deals with methods considering the tensile creep of concrete due to shrinkage. It was proved, that the tensile creep can be taken into account by simplified methods called Age-adjusted Effective Modulus Method with the ageing coefficient χvalue falling between 0.4 and 0.45. Calculated values were experimentally verified by means of Ring-test.

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Sarsam, Saad Issa, e Nuha Mashaan. "Detecting the Influence of Additives on Asphalt Concrete Durability". Jurnal Kejuruteraan 34, n. 1 (30 gennaio 2022): 51–58. http://dx.doi.org/10.17576/jkukm-2022-34(1)-05.

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Modification of asphalt cement with additives is a sustainable issue. An attempt was made in the present assessment to detect the influence of modification of the asphalt binder by 2 % silica fumes and 4 % fly ash additives on the durability in terms of fatigue life of asphalt concrete mixture under short-term and long-term ageing processes and moisture damage. Asphalt concrete slab samples of wearing course was prepared and compacted by roller. The beam specimens of 400 mm length and 50 mm height and 63 mm width were extracted from the slab samples. The beam specimens had practiced the four-point repeated flexural bending beam test. The fatigue life was monitored as the number of load repetitions to reach the failure under three constant micro strain levels of (250, 400, and 750). The reduction in fatigue life after long-term ageing for control, silica fumes modified, and fly ash modified mixtures was (74.7, 38.4, and 60) %, (66.2, 52.4, and 64.3) %, (63.9, 63.1, and 57.5) % under 250, 400, and 750 microstrain levels respectively. However, the reduction in fatigue life after practicing moisture damage for control, silica fumes modified, and fly ash modified mixtures was (71.2, 59.6, and 37.2) %, (37.1, 64.9, and 11.2) %, (71, 84.8, and 32.2) % under (250, 400, and 750) microstrain levels respectively. It was concluded that Fly ash exhibit lower susceptibility to long-term ageing process as compared to other mixtures, while silica fumes exhibit lower susceptibility to moisture damage as compared to other mixtures.

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Randl, Norbert. "Innovative approaches for strengthening existing concrete structures". MATEC Web of Conferences 323 (2020): 01020. http://dx.doi.org/10.1051/matecconf/202032301020.

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The demand of effective and low-invasive methods for strengthening existing concrete structures is continuously increasing due to the ageing infrastructure. High performance materials can beneficially be applied to provide sustainable and robust strengthening solutions. The present article presents some exemplarily selected methods and innovative approaches for subsequent strengthening of existing RC structures. Main results of experimental investigations are summarized and future research topics identified.

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Zvolánek, Lukáš, e Ivailo Terzijski. "Relaxation of Structural Concrete due to its Shrinkage in Terms of Age-Adjusted Effective Modulus Method". Key Engineering Materials 737 (giugno 2017): 471–76. http://dx.doi.org/10.4028/www.scientific.net/kem.737.471.

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This paper focuses on the calculation of residual stresses due to shrinkage with a tensile creep effect. Whereas the shrinkage of concrete causes stresses in the material, the tensile creep counteracts the shrinkage as a stress relaxation mechanism. The main objective of this paper is to evaluate the ageing coefficient c (referred to as Trost-Bazant Coefficient) reflecting the load history. The coefficient is used for the residual stress analysis by means of a simplified method called Age-adjusted Effective Modulus Method. The tensile creep effect was evaluated according to the rheological model provided by Eurocode 2. Although the Eurocode predicts the creep for the structural members subjected to compressive stresses, this study proves that it can be used for the tensile creep prediction as well. We tested three types of concrete: reference concrete, high-performance concrete with reduced shrinkage magnitude by means of special admixtures, and fibre concrete with the content of polypropylene fibres. From the obtained results, it can be stated, that the ageing coefficient can be considered to be the value of 0.45 for any shrinkage development. It was also proved, that the tensile creep value essentially affects the magnitude of residual stresses, even in the “early age” concrete. The correctness of the calculated residual stresses was verified by means of a Ring-test.

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Sarsam, Saad Issa. "Monitoring the Durability Issues of Asphalt Concrete Mixtures". October 2023 4, n. 4 (1 dicembre 2023): 1–5. http://dx.doi.org/10.36937/cebel.2023.1804.

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The asphalt concrete mixture is prone to environmental issues such as moisture damage and ageing. This may exhibit a great significance in the service performance of asphalt concrete pavement mixtures which may be more susceptible to many types of early distresses throughout its fatigue life. In the present investigation, asphalt concrete mixtures were prepared and compacted with the aid of laboratory roller compaction into a slab samples. optimum binder content was implemented. Extra samples were prepared at higher and lower binder content of 0.5 % (above and below the optimum). Asphalt concrete beam specimens were obtained from the prepared slab samples with the aid of a diamond saw. Part of the Asphalt concrete beam specimens were tested under four point’s repeated flexural stresses after practicing moisture damage while another part was subjected to long term ageing. The rate of change in the flexural strength was monitored and compared among the various testing conditions at 20 ºC environment and under constant micro-strain level of 750. It was observed that the lower flexural strength was observed for moisture damaged specimens while higher flexural strength could be detected for aged specimens as compared with the control mixtures. The binder content exhibits a significant influence on flexural strength of the asphalt concrete specimens since it declines significantly at higher or lower binder content as compared with that of specimens prepared at the optimum.

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Mohammed, Abdullahi Ali, Ramadhansyah Putra Jaya, Étienne Joseph Marie Delbrel, Choong Wee Kang, Sien Ti Kok, Haryati Yaacob, Norhidayah Abdul Hassan, Nor Hayati Abdul Hamid e Noram Irwan Ramli. "Stiffness Modulus of Asphaltic Concrete Incorporating Coir Fibre and Subjected to Aging". E3S Web of Conferences 65 (2018): 02003. http://dx.doi.org/10.1051/e3sconf/20186502003.

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The aim of this paper is to investigate the performance response of a set of coir fibre modified asphalt samples subjected different ageing conditions and containing three different fibre contents. The laboratory experimental programs are indirect tensile test at 25°C and repeated load axial test at 40°C. The results showed that the fibres improved the mixture’s performance. The main findings obtained at 25°C for short and long-term ageing reveal that low fibre content at around 0.3% per aggregate weight display a stiffness modulus up to 14% higher than that of unmodified mixtures, hence showing that fibres may improve the bearing capacity and rut-resistance of asphalt mixtures. Conversely, as the amount of fibre increases to 0.5% and 0.7%, the stiffness decreases to the point of becoming unacceptably low, almost 80% lower than unmodified mixes stiffness. However the data also reveal that high fibre contents at 0.5% and above completely neutralize the impact of ageing on the mixture, indicating that fibre-modified mixtures would yield longer lives.

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32

McGovern, M. E., B. Behnia, W. G. Buttlar e H. Reis. "Concrete Testing: Characterisation of oxidative ageing in asphalt concrete – Part 2: Estimation of complex moduli". Insight - Non-Destructive Testing and Condition Monitoring 55, n. 11 (1 novembre 2013): 605–9. http://dx.doi.org/10.1784/insi.2012.55.11.605.

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33

Abdulrazeg, Aeid Ali, Jamaloddin Noorzaei, Mohamed Saleh Jaafar, Parvin Khanehzaei e Thamer Ahmed Mohamed. "THERMAL AND STRUCTURAL ANALYSIS OF RCC DOUBLE-CURVATURE ARCH DAM". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, n. 3 (9 giugno 2014): 434–55. http://dx.doi.org/10.3846/13923730.2013.801897.

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This paper focuses on the development, verification and application of a three-dimensional finite element code for coupled thermal and structural analysis of roller compacted concrete arch dams. The Karun III Arch dam located on Karun River, Iran, which was originally designed as a conventional concrete arch dam, has been taken for the purpose of verification of the finite element code. In this study, RCC technology has been ascertained as an alternative method to reduce the cost of the project and make it competitive. A numerical procedure to simulate the construction process of RCC arch dams is presented. It takes into account the more relevant features of the behavior of concrete such as hydration, ageing and creep. A viscoelastic model, including ageing effects and thermal dependent properties is adopted for the concrete. The different isothermal temperature influence on creep and elastic modulus is taken into account by the maturity concept. Crack index is used to assess the occurrence of crack and evaluate the level of safety of the dam. This study demonstrates that, high tensile stress concentration has been observed at the lower part and the abutment boundaries of the dam.

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Okajima, Tatsuo, Shinji Kawabe, Yosuke Hayashi e Taizo Mizutani. "The Surface Finish Evaluation of Concrete Buildings Effected by Ageing". Concrete Research and Technology 9, n. 1 (1998): 63–70. http://dx.doi.org/10.3151/crt1990.9.1_63.

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35

Mamand, H., J. Chen e S. J. Barnett. "Experimental and modelling investigation of mechanical behaviour of ageing concrete". Construction and Building Materials 155 (novembre 2017): 1138–46. http://dx.doi.org/10.1016/j.conbuildmat.2017.08.123.

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36

Bilcik, Juraj, Vladimir Benko e Ludovít Fillo. "Ageing of Concrete Containers for the Disposal of Nuclear Waste". IABSE Symposium Report 86, n. 6 (1 gennaio 2002): 92–99. http://dx.doi.org/10.2749/222137802796337080.

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Aniskin, Nikolai, Alexey Shaytanov e Mikhail Shaytanov. "Geosynthetic liner: A modern solution for a concrete dam constructed from particularly lean roller-compacted concrete". E3S Web of Conferences 410 (2023): 05013. http://dx.doi.org/10.1051/e3sconf/202341005013.

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This paper discusses the issue of seepage control in gravity dams made of compacted lean concrete. Several possible design options are outlined. The benefits of using geocomposite impervious blankets are explained. A description of different types of geocomposites is given, including their composition and component parameters. Basic properties of geosynthetics are discussed, along with methods for defining them, such as water permeability, tensile strength, puncture resistance, and ageing. Finally, the main areas for future research are formulated, although it may be helpful to provide more detail on the specific focus of this research.

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Hsino, Mahmoud, e Jerzy Pasławski. "Phase Change Materials as a Modifier of Ageing Cement Concrete in Hot and Dry Climate". Advanced Materials Research 804 (settembre 2013): 129–34. http://dx.doi.org/10.4028/www.scientific.net/amr.804.129.

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This paper is devoted to the use of Phase Change Materials as a cement concrete modifier in Middle East climate. Due to large amplitude of daily air temperature in these conditions, Phase Change Materials can be used to reduce the dynamic of thermal peak in an ageing concrete. Partial results of studies to determine the influence of various factors on the effects of modifications are presented

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Zhang, Jin Yang. "The Tests and Measures of Concrete Ageing and Steel Bar Corrosion of the Salt Free Contaminated Inland Waterlocks". Applied Mechanics and Materials 71-78 (luglio 2011): 4525–32. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.4525.

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Abstract (sommario):

There are mainly three phenomena, i.e. cracks, infiltration and denuding for judging the aging and defects from hydraulic concrete constructions. The inland waterlocks’ concrete ageing with salt free contamination are found basically the concrete denuding, rebar erosive expansion cracks and concrete surface gravel exposure and freeze thawing peeling-off as well occasionally. The severe aging phenomena always occur in some small structures in work bridges, sub work bridges, railway bridges and concrete waterlocks etc, especially in boundary beams or flange plates of the said beams. The result manifests that the test result is completely in conformity with the actual situation in the test of internal concrete steel bar erosion by means of Eigenvalue K method and half-cell potential method. In order to prevent steel bars in the concrete from eroding and guarantee the durability of waterlocks, currently the treating method used most frequently is the waterlock concrete surface carbonization resistance treatment

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40

Alma’aitah, Mohammad, Bahman Ghiassi e Ali Dalalbashi. "Durability of Textile Reinforced Concrete: Existing Knowledge and Current Gaps". Applied Sciences 11, n. 6 (19 marzo 2021): 2771. http://dx.doi.org/10.3390/app11062771.

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This paper aims to provide a review of the current literature on the durability of textile-reinforced concrete and mortar (TRC/TRM) composites. Most previous studies have focused on the role of chemical attacks, freeze-thaw conditions, and high temperatures on the mechanical performance of these composites. Information on the long-term performance of TRCs under synergistic action of mechanical and environmental loads is scarce. Considering the variety of fabrics and matrices used for the production of TRC composites, the existing data are still very limited and comprehensive studies are needed in this field. Additionally, due to the lack of standard procedures, different approaches are often followed for durability or post-ageing mechanical tests, or sufficient data on the curing and post-ageing preparation procedures followed are not provided. These have led to incompatibility of the existing data and in some cases contradictory results on the durability of these materials.

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Asphaug, Silje Kathrin, Berit Time e Tore Kvande. "Moisture Accumulation in Building Façades Exposed to Accelerated Artificial Climatic Ageing—A Complementary Analysis to NT Build 495". Buildings 11, n. 12 (23 novembre 2021): 568. http://dx.doi.org/10.3390/buildings11120568.

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Abstract (sommario):

Building façades must endure severe climatic exposure throughout their lifetimes. To prevent damage and expensive repairs, ageing tests are used in durability assessments. The NT Build 495 describes an artificial ageing procedure to address building material and component resistance to ultraviolet (UV) light, heat, water, and frost using a climate simulator. The test has been used for decades to investigate exterior surface materials and façade products but has only recently been adopted for multi-layered systems. This study investigates moisture accumulation in a façade system for retrofitting based on concrete and thermal insulation. Hygrothermal simulations of the façade system subjected to ageing were conducted. Moisture accumulation was considered theoretically for the current test procedure and compared to a modified setup in which the interior climate was controlled at 21 °C. Physical measurements were performed in the climate simulator to determine the boundary conditions. Results showed that moisture accumulation in the thermal insulation was largely affected by the type of concrete, that applying a water-repellent surface treatment reduced moisture accumulation, and that the current setup resulted in less moisture accumulation compared to the modified setup. The latter implicates accelerated degradation with the modified setup.

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42

Xiao, Li Ying. "A Review of Detection, Evaluation and Repair Technology for Hydraulic Concrete Structures". Advanced Materials Research 690-693 (maggio 2013): 805–10. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.805.

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This paper provides a review of the progress in America, Europe, Japan and china withnumerous standardizations and investigations for the protection and repair of hydraulic concrete structures.These researches include detection technologies, evaluation methods, applications of newconcrete reinforcing and repair materials. This paper identifies the significant progress made by theInternational Commission on Large Dams(ICOLD).At the same time, some specific investigations are carried out on the ageing of hydraulic concrete structures in china. On this basis, the detection, assessment and remediation analysis of hydraulic concrete structures are summed up, and someadvice is put forward to the next stage of work.

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Angst, Ueli M., Yurena Seguí Femenias e Fabrizio Moro. "The role of durability monitoring in taking infrastructure maintenance to the level of industry 4.0". ce/papers 6, n. 5 (settembre 2023): 1014–18. http://dx.doi.org/10.1002/cepa.2066.

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AbstractOver the last years, significant advances were made with respect to sensors, data logging, data communication, and algorithm‐based data analysis. These developments have the potential to take structural health monitoring, especially structural corrosion health monitoring, to the next level. This contribution focuses on corrosion and durability monitoring of reinforced concrete structures. It is discussed how monitoring can play an important role in the diagnosis of the condition of a structure, as well as in predicting the future evolution of material's ageing and related deterioration processes. Measuring chemical and physical parameters in the concrete can serve as “early warning system” to detect potential durability issues ahead of time and optimize repair. Combined with modelling tools and taking into account the exposure conditions, such information can form the basis for predictive maintenance. In addition, the roles of monitoring as a method for checking the effectiveness of repair products in‐situ and to assess the performance of new concretes with low greenhouse gas emissions are discussed.

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Ross, Charlotte. "Imagined communities: initiatives around LGBTQ ageing in Italy". Modern Italy 17, n. 4 (novembre 2012): 449–64. http://dx.doi.org/10.1080/13532944.2012.706997.

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LGBTQ ageing is an under-researched but vital issue, given the cultural invisibility of older LGBTQ individuals and Italy's ageing population. This article explores initiatives around LGBTQ ageing, considered in relation to the hypothesis that LGBTQ populations may develop effective strategies for ‘successful ageing’, by establishing queer cultural spaces and support networks. After a brief contextualisation of key issues the author focuses on a case study of a lesbian community in Bari which is planning a residential arrangement for ‘older lesbians’. Drawing on interviews conducted in January 2011, the coping strategies or forms of ‘resilience’ developed by this community are identified and analysed. It is argued that while plans for a residential facility remain unrealised, this community demonstrates a degree of ‘resilience across the life course’, through reciprocal support, and socio-cultural and political innovation. However, interviews also reveal the difficulties of progressing from an ‘imagined community’ to its concrete realisation.

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Arel, Hasan Şahan, Ertug Aydin e Sudarshan D. Kore. "Ageing management and life extension of concrete in nuclear power plants". Powder Technology 321 (novembre 2017): 390–408. http://dx.doi.org/10.1016/j.powtec.2017.08.053.

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46

Peach, B., M. Petkovski, J. Blackburn e D. L. Engelberg. "The effect of ageing and drying on laser scabbling of concrete". Construction and Building Materials 188 (novembre 2018): 1035–44. http://dx.doi.org/10.1016/j.conbuildmat.2018.08.131.

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47

Purnell, P., e J. Beddows. "Durability and simulated ageing of new matrix glass fibre reinforced concrete". Cement and Concrete Composites 27, n. 9-10 (ottobre 2005): 875–84. http://dx.doi.org/10.1016/j.cemconcomp.2005.04.002.

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48

Szymanik, Barbara, Sam Ang Keo, Franck Brachelet e Didier Defer. "Investigation of Carbon Fiber Reinforced Polymer Concrete Reinforcement Ageing Using Microwave Infrared Thermography Method". Applied Sciences 14, n. 10 (20 maggio 2024): 4331. http://dx.doi.org/10.3390/app14104331.

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Abstract (sommario):

This study presents the utilization of the microwave infrared thermography (MIRT) technique to identify and analyze the defects in the carbon-fiber-reinforced polymer (CFRP) composite reinforcement of concrete specimens. At first, a set of numerical models was created, comprising the broadband pyramidal horn antenna and the analyzed specimen. The utilization of the system operating at a power of 1000 W in a continuous mode, operating at frequency of 2.45 GHz, was analyzed. The specimen under examination comprised a compact concrete slab that was covered with an adhesive layer and, thereafter, topped with a layer of CFRP. An air gap represented a defect at the interface between the concrete and the CFRP within the adhesive layer. In the modeling stage, the study investigated three separate scenarios—a sample with no defects, a sample with a defect located at the center, and a sample with a numerous additional random defects located at the rim of the CFRP matte—to analyze the effect of the natural reinforcement degradation in this area. The next phase of the study involved conducting experiments to confirm the results obtained from numerical modeling. In the experiments, the concrete sample aged for 10 years with the defect in the center and naturally developed defects at the CFRP rim was used. The study employed numerical modeling to explore the phenomenon of microwave heating in complex structures. The aim was to assess the chosen antenna design and identify the most effective experimental setup. These conclusions were subsequently confirmed through experimentation. The observations made during the heating process were particularly remarkable since they deviated from earlier studies that solely conducted measurements of the sample post-heating phase. The findings demonstrate that MIRT has the capacity to be employed as a technique for detecting flaws in concrete structures reinforced with CFRP.

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Francke, Barbara, e Artur Piekarczuk. "Experimental Investigation of Adhesion Failure between Waterproof Coatings and Terrace Tiles under Usage Loads". Buildings 10, n. 3 (17 marzo 2020): 59. http://dx.doi.org/10.3390/buildings10030059.

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Abstract (sommario):

This paper analyses the mechanism of the loss of functional properties of water-impermeable products used under ceramic tiles bonded with adhesives. Recorded damages were caused by selected ageing factors and were measured by the loss of adhesion of individual layers of the set. The analyzed phenomenon is found mainly on terraces and balconies located in a mid-European transitional climate, i.e., exposed to temperatures passing through 0 °C for three seasons a year. The tests reflected the action of three main functional factors, i.e., temperatures, water and freeze/thaw cycles. Tested waterproof coatings were grouped into three types, i.e., dispersion, cementitious and reaction resin-based products. Research kits consisted of liquid-applied water-impermeable products laid on a concrete substrate, adhesives and tiles. Comparing the effects of the action of the above-mentioned ageing factors revealed that water has the greatest impact on the reduction of the tensile adhesion strength of such sets. The adhesion of waterproof coatings to the concrete substrate showed higher values than the adhesion between the waterproof coating and the tile adhesive layers, regardless of the coating material. Both for samples not exposed to ageing factors, and for those exposed to such impacts, failure usually occurred in the adhesive layer or between the tile adhesive and the waterproof coating, without damaging the waterproof layer. The loss of adhesion of finishing layers to the substrate was not accompanied by a loss of tightness of the waterproof coating. The impact of negative water ageing was particularly destructive on the adhesion of cement-based tile adhesives to waterproof coatings made of polymer with a water dispersion of absorbability above 7% (V/V). There was no correlation among the results of adhesion of the finishing layers to the waterproofing layer after the action of the three ageing factors, i.e., water contact, elevated temperature and freeze/thaw cycles.

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Misák, Petr, Dalibor Kocáb e Petr Cikrle. "Determination of a Suitable Moment for Formwork Removal from a Concrete Structure Using Rebound Hammer Test Methods". Solid State Phenomena 322 (9 agosto 2021): 23–27. http://dx.doi.org/10.4028/www.scientific.net/ssp.322.23.

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Abstract (sommario):

Determining the compressive strength of concrete in the early stages of ageing has been an increasingly relevant topic in recent years, particularly with regard to the safe removal of formwork from a structure or its part. The compressive strength of concrete which designates safe removal of formwork without damaging the structure can be referred to as "stripping strength". It is undoubtedly beneficial to be able to determine the moment of safe formwork removal in a non-destructive manner, i.e. without compromising the structure. Modern rebound hammer test methods seem to be a suitable instrument with which it is possible to reduce the length of technological breaks associated with concrete ageing to a minimum, and consequently, reduce the total cost of the construction. However, the use of these methods presents a number of challenges. As many conducted experiments have shown, there is no single conversion relationship (regression model) between non-destructive rebound hammer test methods and compressive strength. It is therefore advisable to always create a unique conversion relationship for each individual concrete. In addition, it must be noted that conventional regression analysis methods operate with 50% reliability. In construction testing, however, the most common is the so-called characteristic value, which is defined as a 5% quantile. This value is therefore determined with 95% reliability. This paper describes the construction of a so-called "characteristic curve", which can be used to estimate the compressive strength of concrete in a structure using rebound hammer test methods with 95% reliability. Consequently, the values obtained from the characteristic curve can be easily used for practical applications.

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