Fig. 3 Compressive strength of SSC made with 10, 15 and 20% calcium sulfate (CS) and 0.2, 0.5, and 0.8% KOH: effect of alkaline activator for each CS content Hydration mechanisms of supersulfated cement: the role of alkali …
Nowadays, the inclusion of calcium sulfate is an integral ingredient in Portland cement. Despite thousands of studies over several decades, many questions about the role of calcium sulfate on the cement phases (C 3 A and C 3 S) hydration, its mechanisms, and the so-called "optimum sulfate content" persists.
Calcium sulfate. J L RICCI, ... H ALEXANDER, in Bioceramics and their Clinical Applications, 2008. 14.2.1 Gypsum and its derivatives. CS cements begin as gypsum, or calcium sulfate dihydrate (CaSO 4 · 2H 2 O), which is either mined from the earth or produced through more controlled chemical processes (Randolph, 1971).Gypsum and …
As a major mineral of Portland cement, the hydration of tricalcium aluminate (C 3 A) has a significant impact on various properties of cement-based materials. However, there is little consensus on its mechanism, especially the interaction between C 3 A and gypsum which usually co-exist in cement systems. Recent researches have shown that …
Sulfate-bearing soils is widely distributed around the world, and this type of soil is prone to rock and soil disasters such as dissolution, corrosion of foundations, and …
External sulfate attack (ESA) is a dominant threat to the durability of concrete exposed permanently to sulfate environments, such as groundwater, sea water, salted soil, and saline lakes [1–3].The durability deterioration of concrete caused by ESA is a complicated chemo-mechanical process, which involves the sulfate diffusion in …
sulphate in portland cement clinker may originate from the clay or calcium sulphate of the raw mix, from the fuel, or from the use of mineralizers. its retention in the clinker is influenced by the kiln atmosphere. studies are in progress of the role of sulphate in the cement making process and the ways in which it may alter either the compound ...
Calcium sulfate is used in Portland cement to control the C 3 A reaction to induce the optimum hydration of C 3 S to occur. The amount of calcium sulfate in the Portland cement influences the hydration, rheology, setting, phase assemblage, …
The amount of calcium sulfate in the Portland cement influences the hydration, rheology, setting, phase assemblage, porosity distribution, and strength in cementitious materials.
Sulfate-Resistant Cement: The primary ingredient in concrete is cement, and using sulfate-resistant cement is the foundation of sulfate attack prevention. This type of cement contains a lower percentage of tricalcium aluminate (C 3 A), which is highly reactive with sulfates. It helps mitigate the chemical reactions that lead to expansion and ...
Calcium sulfoaluminate-belite (CSAB) cement is considered a viable and environmentally friendly alternative to Portland cement. Ye'elimite or calcium sulfoaluminate which is the primary phase of CSAB cement undergoes rapid hydration, leading to the formation of ettringite or monosulfate as the major hydration product. The …
Abstract High-belite sulfoaluminate cement (HBSC), with low carbon dioxide emissions, can be used to repair old concrete. Calcium sulfate plays a significant role in hydration of ye'elimite, but a comprehensive study of the effects of the four different types and dosages of calcium sulfate on the hydration of HBSC is lacking. This study …
🕑 Reading time: 1 minute Sulphate attack on concrete is a chemical breakdown mechanism where sulphate ions attack components of the cement paste. The compounds responsible for sulphate attack on concrete are water-soluble sulphate-containing salts, such as alkali-earth (calcium, magnesium) and alkali (sodium, potassium) sulphates that are …
SSC have been used for decades and are usually composed of up to 90% blast furnace slag (BFS, SSC-BFS), 5-15% calcium sulfate (CS) and 5-15% of an alkaline activator; the latter is mainly Portland ...
Sulfate in concrete has connotations of being negative and causing durability issues. Issues with sulfate in concrete do emerge when there is too much sulfate present, but it is actually a necessary …
The calcium sulfate (CS) plays a crucial role in pro-viding the SO 3 2-ions, which react with the Ca2? and Al3? ions contained in GBFS to form ettringite (C 6AS 3H 32). With …
The self-regulating on cohesion properties of calcium phosphate/ calcium sulfate bone cement improved by citric acid/sodium alginate Colloids Surf B Biointerfaces. 2023 Nov:231:113548. doi: 10.1016/j ... which also played a regulating role in the conversion of materials to HA. The morphology, physicochemical properties, and cell compatibility ...
Temperature plays a significant role in determining the hydration behavior of calcium sulfoaluminate (CSA) cement, which is a sustainable alternative to Portland …
Even if cement is a well-consolidated material, the chemistry of cement (and the chemistry inside cement) remains very complex and still non-obvious. What is sure is that the hydration mechanism plays a pivotal role in the development of cements with specific final chemical compositions, mechanical properties, and porosities. This …
The results show that the OPC content in the SSC composition also plays a central role to optim ize the . ... partially anhydrous calcium sulphate (90%) and Portland cement (10%), mixed …
The amount of calcium sulfate in the Portland cement influences the hydration, rheology, setting, phase assemblage, porosity distribution, and strength in cementitious materials.
Precautions against sulfate attack. Q. What are the precautions against sulfate attack? A. Sulfate attack is either a chemical or physical reaction, or both, between sulfates—usually in soil or ground water and concrete or mortar.The chemical reaction is primarily with calcium aluminate hydrates in the cement-paste matrix, often causing deterioration.
The sulfate ions, which come from soil, seawater, react with the cement hydrates (calcium hydroxide, C-S-H. AFm phases) to form ettringite, gypsum and thaumasite in presence of carbonates [1,2,3]. The use of supplementary cementitious materials to control the expansion is well established and a number of reviews have …
a b s t r a c t Presented within is a critical overview of the effect of sulfates on cement hydration, properties, and optimum sulfate content in Portland cement. Calcium sulfate is used in ...
4.1 Calcium Sulfate Solutions (CaSO 4) The action of calcium sulfate is limited by its solubility in water, 15.2 mmol/l at 20°C (≈1.46 g SO 2− 4 /l). However, when these ions enter concrete, the pH is different and there is a change in the reactivity and solubility with respect to ground water.
Calcium - Compounds, Reactions, Role: The most important calcium compound is calcium carbonate, CaCO3, the major constituent of limestone, marble, chalk, oyster shells, and corals. Calcium carbonate obtained from its natural sources is used as a filler in a variety of products, such as ceramics, glass, plastics, and paint, and as a …
Calcium sulfate (CaS) has been shown to be a reasonable alternative to autogenous bone graft for treating bone lesions in dentistry. The aim of this work was an histological study of the bone healing of defects treated with calcium sulfate in the form of cement or beads, in animal. Eight New Zealand …
The effect of C 3 A polymorphism, the calcium sulfate source, and the addition of limestone on the hydration kinetics and rheology of cement pastes and their interaction with a lignosulfonate-based admixture were analyzed. Two clinkers produced in industrial cement rotary kilns using the same raw materials and process were produced; …
Calcium sulfoaluminate (CSA) cement can be used as a replacement for Portland cement to reduce CO 2 emissions. However, the performance of CSA …
1.Introduction. Over the past few years, there has been a growing effort to reduce CO 2 emissions in cement production and enhance the mechanical properties of cement-based materials. Pozzolanic clay has many applications in all fields and is used as an additive in cement (Zhang et al., 2022).One effective additive that has been widely used for this …
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