- منطقة بودونغ الجديدة ، شنغهاي ، الصين .
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However, when the mortar is at rest, the cement particles get together due to hydration and flocculation, the fluidity of mortar decreases and its viscosity increases with time [4]. To quantitatively investigate thixotropy of fresh concrete, Roussel developed a thixotropy model to describe the change in the viscosity of cement paste over time ...
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If the foremost particle network is completely de-flocculated or the introduced shear is limited and not strong enough to break further agglomerates, equilibrium is obtained [11,23,25,26]. After shear (at rest), particles will agglomerate again. Thus, the particle network is a function of the cement paste's shear history (i.e., mixing) [18,20 ...
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the rate of structural buildup at rest, the degree of hydration, mechanical properties, and durability [2–7]. ... of the presence of the cement particles and other added particles. In this approach, the material parameters, such as viscosity, may depend on the particle concentration, also ...
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The thixotropic behavior of cement paste was measured using a DV-II + Pro viscometer (Brookfield, USA) equipped with a coaxial cylinder sample adapter and a temperature controlling system. A three-step shearing procedure was carried out to characterize the breakage and aggregation kinetics of cement particles as illustrated in …
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In cement-based suspensions, once the shear energy is removed, the initial particle structural build-up is dominated by colloidal surface interactions. Furthermore, as cement-based suspensions have high solid volume fractions, particle contact interactions also play an important role in particle structuration.
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Oscillatory rheology has proved a promising method to measure the nature of interactions between inorganic particles in suspension. In this work, small oscillatory rheology (SAOS) is used to compare the nature of interactions in an ordinary Portland cement (OPC) and a more sustainable alkali-activated binder (AAB).
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The structural build-up of cement-based materials describes the increase in rheological parameters with resting time [1,2,3,4,5,6,7,8,9].It originates from flocculation and the bridging effect of C-S-H between cement particles [2,10].This behavior is time-dependent and reflects the structuration of cement paste at rest.
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ed concrete materials based on sulpoaluminate cement were prepared by the chemical ing method. The effects of water–cement ratio, ing agent, and ing stabilizer on the mechanical and thermal properties of ed concrete were studied. Meanwhile, a portion of cement was replaced with ed phenolic particles …
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Predominantly granular soils that have minute amounts of clay particles can be stabilized by blending them with ____. Portland cement ____ hammers use a heavy weight lifted up vertical rails called leads. Drop ... ____ may rest on a continuous concrete footing below grade, such as a basement wall, and extend above grade to form the exterior or ...
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The shape of cementitious materials at stoppage is well accepted to be related to the yield stress [33,34,35,36]. Over the past years, a greater attention has been taken to quantitatively obtain reliable relations between yield stress values and either spread flow or slump tests. Roussel and …
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Additives such as nano-silica and fly ash are widely used in cement and concrete materials to improve the rheology of fresh cement and concrete and the performance of hardened materials and increase the sustainability of the cement and concrete industry by reducing the usage of Portland cement. Therefore, it is important …
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Surface area and size distribution of cement particles in hydrating paste as indicators for the conceptualization of a cement paste representative volume element. ... approaches for multiphase composite materials commonly applied within the continuum solid mechanics domain rest on defining a representative volume element (RVE) of a …
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The cement used in this study was Type I cement from Lehigh Hanson and its chemical composition is shown in Table 1.The specific gravity of cement and the synthetic calcium carbonate polymorphs are shown in Table 2.Distilled water was used to prepare all of the specimens and the water-to-solid (w/s) ratio was kept constant at 0.4.
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In the present work, rheological behaviors of fresh cement paste are studied based on multi-disciplinary approaches, i.e., colloidal suspension using attractive van der Waals force, rheology using the Bingham model and Bingham–Papanastasiou model, which are able to describe the behavior of cement pastes before and after yield stress, and …
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The laser diffraction (LD) measurement of the entire particle size distribution is currently being used by cement producers for quality control of their cements while still measuring the Blaine, which is based on surface area measurement. Despite its wide use by the cement industry, LD is not a standardized test.
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General behavior of fresh cement-based systems at rest described through yield stress evolution and underlying cement particle interaction and C-S-H nucleation and growth. The freshly sheared suspension starts in a dispersed state (a), then exhibits initial flocculation due to non-contact interactions.
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