Which- where the cement product in its early age is exposed to harsh ever may be the case, loss of water in the fresh mixes or during atmosphere, faster rate of drying should be expected with conse- the early age brings cement particles and other conglomerate sub- quent formation of harmful cracks, and this is also the case when stances closer ...Web
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The presented research aims to evaluate the performance of concrete against environmental issues such as alkali-silica reactivity, drying shrinkage, and sulfate resistivity to ensure long life. Ultrafine SBR powder at 0%, 3%, 5%, 7%, and 10% cement replacement is used.Web
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The changes in the moisture content and porosity led to variations in the concrete strength. In this study, the compressive strength of concrete during drying at elevated temperatures (40 °C, 105 °C, 150 °C, 200 °C, and 250 °C) was tested. The results showed that the compressive strength first decreased and then increased with a …Web
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In particular, silica fume is mainly utilized for ultra-high performance concrete (UHPC), ... Creep and drying shrinkage performance of concrete composite comprising waste polypropylene carpet fibres and palm oil fuel ash. J Build Eng, 30 (2020), Article 101250, 10.1016/j.jobe.2020.101250.Web
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Traditionally, performance of fresh dry concrete is commonly indicated by the consistency and unit weight, and Vebe time (VBT) is used to characterize the …Web
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Accurate modelling of moisture diffusion is essential, as it dominates the drying process in concrete and governs the development of shrinkage strains that affect the short- and long-term deformation and cracking behaviour of structural elements. Key models available in the literature use porosity as the main parameter to predict the diffusivity of …Web
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Drying times vary depending on the cement type, aggregate size, and admixtures used in your mix design. Quick-setting concrete has additives that speed up drying times, …Web
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In this work, shrinkage performance of ordinary portland cement (OPC) paste containing various alkali salts was characterized at two drying conditions, namely: nitrogen gas and air. The results show that incorporation of alkalis dramatically increases shrinkage magnitude, but reduces shrinkage kinetics of OPC, regardless of source and type of …Web
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To elucidate drying shrinkage effect and characterize early-stage microcracking development in PLC and OPC concretes [8], this study employs the SHG technique [30], [31]. Drying shrinkage over a 55-day period is considered as a damage mechanism that results in microcracks near the surface of early-age concrete.Web
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The drying of concrete may induce micro-cracks inside cement paste or between cement paste and aggregates. The rewetting could not only lead to self-sealing of microcracks, but also to changes in mechanical properties and to decrease in permeability and diffusivity. ... Role of pore pressure on cracking and mechanical performance of …Web
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The dredged silt exposed to the air is highly expected to be used to replace cement in large quantities due to its richness in aluminosilicates, which is in line with the dual-carbon background. Herein, a systematic exploration on the basic properties and hydration products of sintered silt ash-blended (SSA-blended) cement is conducted, …Web
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Drying times vary depending on the cement type, aggregate size, and admixtures used in your mix design. Quick-setting concrete has additives that speed up drying times, allowing you to walk on its surface in just two hours. Standard and high-performance concrete takes up to 48 hours to dry. Mixtures with large aggregate pieces can extend drying ...Web
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Concrete is a porous composite material made up of cement stone, coarse and fine aggregates, and pores. The drying of concrete is primarily manifested as the water loss of cement stone, accompanied by changes in cement stone structure and performance due to the low water absorption capacity of aggregate [16].Web
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The large volume of hydrated cement paste can increase drying shrinkage in high-performance concrete. As the volume of the cement paste is large, loss of water from within can cause a considerable reduction in the volume of the concrete mass. This makes the concrete with high cement content and/or low water to cement ratio more prone to …Web
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Melo Neto A A, Cincotto M A, Repette W. Drying and autogenous shrinkage of pastes and mortars with activated slag cement. Cement and Concrete Research, 2008, 38(4): 565–574. Article Google Scholar Song W, Yin J. Hybrid effect evaluation of steel fiber and carbon fiber on the performance of the fiber reinforced concrete.Web
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The amount of drying shrinkage that occurs in concrete structures depends on the constituent materials, mixture proportions, curing, drying environment, and restraint. Tensile stresses caused by restraint to drying shrinkage can occur before concrete tensile strength is fully developed. When concrete is restrained by reinforcement, subgradeWeb
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Drying shrinkage deformation due to moisture migration is a major concern in cementitious materials and can lead to a high probability of cracking, resulting in a deterioration in long-term performance and serviceability.In this paper, the primary mechanisms of drying shrinkage, mitigation strategies and the research gaps are …Web
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During the wetting and drying (W-D) regimes, volumetric shrinkage and microcracking are cyclically produced by the removal of water in the pores and cement paste in drying processes and water is ...Web
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As part of the research on cement composites using cellulose nanocrystal (CNC) aqueous solution instead of general water, this study produced high-toughness cement composites reinforced with flax and steel fibers to improve the tensile deformation capacity, assessing the isothermal conduction calorimetry analysis, drying shrinkage, …Web
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Investigation of the effect of early age-curing methods, including water curing, curing in elevated-temperature water, and CO2 curing, on drying shrinkage of alkali-activated slag concrete shows that water curing decreased dryingshrage of both C30 and C50 AASC moderately compared to air curing, while it was more effective for C30 AASC.Web
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Ultra-High Performance Concrete (UHPC) is a cementitious, concrete material that has a minimum specified compressive strength of 17,000 pounds per square inch (120 MPa) with specified durability, tensile ductility and toughness requirements; fibers are generally included in the mixture to achieve specified requirements.Web
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HEMC is widely used in dry-mix mortars, and the physical properties evolution of dry-mix mortars is crucial to their applications in different fields. Therefore, the aim of the current work is to investigate the long-term performance of cement mortars with HEMC, including physical properties, hydration and pore structure.Web
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With, V/S is the member volume to surface ratio (in millimeters) to take into account the size and shape influence on concrete shrinkage. Similar to the Eurocode2 shrinkage model, the ACI 209R-92 model considers the size and shape impact a couple of times, for example in the correcting coefficient γ sh,vs or γ sh,d, affecting γ sh, and …Web
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It can achieve even greater efficiency by combining the admixture with expansive agents to provide synergistic effects, giving mitigation of drying shrinkage of up to 80%. Replacing cement with ...Web
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In a paper published in the Proceedings of the National Academy of Sciences, researchers at the MIT Concrete Sustainability Hub (CSHub), French National Center for Scientific Research (CNRS) and …Web
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Creep and drying shrinkage are two important time-dependent properties of high-performance concrete (HPC). In this study, three groups of HPC with same mix proportioning except the type of binding materials were prepared. Their creep behaviour and drying shrinkage characteristics were measured in accordance with the Chinese …Web
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The popularity of high-performance concrete (HPC) has been continuously increasing due to its superior mechanical and durability properties [1], [2]. ... After the exposure to drying conditions internally cured high-performance concrete exhibits higher drying shrinkage than concrete without internal curing. Therefore, the total shrinkage of …Web
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In order to understand the influence of the vibration mixing method on the performance of cement-stabilized aggregate mixture (CSAM), in this study, an unconfined compressive strength test, drying shrinkage test and the influence of gradation characteristics on compressive strength were used to systematically analyze the …Web
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The durability of internally cured concrete (ICC) with silicon–aluminum based fine lightweight aggregate (FLWA) exposed to combined sulfate and wetting–drying attack were conducted through evaluating concrete mass, relative dynamic elastic moduli (RDEM), flexural strength, microstructure and erosion products, with the consideration of …Web
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Drying induced stress gradients [26–30] and incompatibilities between cement paste and aggregates [31–34] can lead to cracking; the larger the specimen, the larger the moisture gradient between the core and the surface of the specimen, the more likely the tensile stress may exceed the tensile strength of the material; and the most …Web
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A large number of binder ingredients such as cement and active mineral admixtures are used in the preparation of high-strength concrete, and the water:binder ratio is extremely low. This leads to a large amount of shrinkage of concrete at the early stage of curing, which poses a great threat to the safety and durability of the structure. To solve …Web
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The internal curing effect of superabsorbent polymer (SAP) on the properties of high performance concrete (HPC) under marine wetting and drying cycles (WD cycles) was investigated. Compressive strength, hydration and chloride migration were experimentally investigated and the results were evaluated by compasison with those …Web
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2.2.1. Concrete . The mixture proportion and properties of the fresh concrete are presented in Table 1, and the long-term concrete properties are shown in Table 2.W, …Web
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Biogas from the digester can also provide the corresponding energy for waste heat recovery in rainy weather or when sunlight is scarce. At the same time, solar energy can also be used to supply energy and heat the kiln to avoid a lack of biomass energy causing the overall system to fail. 1. Cold water storage tank; 2.Web
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Find out how long it takes for concrete to dry for you to be able to walk and drive on it. And learn how you can aid the curing process for best results.Web
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Dry ultra-high performance concrete (DUHPC) is a promising building material with better mechanical and durability properties, developed on the basis of …Web
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The changes in concrete performance with different dry–wet cycles were essentially consistent. Within a certain range, the erosion of concrete became more apparent upon prolonging the dry–wet cycles. The relative flexural strength and relative dynamic modulus of the T3, T7, T14, and T21 specimens peaked at 28, 12, 6, and 4 …Web
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The 56-day drying shrinkage strain of MSFRC reduces by 60% compared with that of PC, and it was confirmed that the drying shrinkage strain decreasing performance was the best. 10. Adding MSF has an effect on restrained drying shrinkage in concrete, as well as on the control of cracking.Web
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