The Relationship between Furized Gypsum Fly Ash Three Constituent Mixture Subtle Structure and Performance
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The paper aims to study the influence of furized gypsum fly ash three constituent mixture subtle structure to performance by analyzing furized gypsum fly ash three constituent IR, SEM, X-ray phase and DTA. The results show that the reason why furized gypsum fly ash three constituent has the characteristics of high strength in the early stage and good endurance quality is that furized gypsum fly ash concrete has the double actived effect of alkali-activated and sulfate-activated. The development of sclerotium strength mainly relies on ettringite and hydrated calcium silicate gel. During the process of hydration, ettringite and CSH gel hydration increase continuously, hardened structure becomes dense and strength continues to increase.Keywords:
Ettringite
Effects of gypsum and calcined gypsum on the early hydration of portland cement were investigated by means of DTA, XRD, IR, and chemically combined water and Ca(OH)2 content. Results show that the cement pastes with calcined gypsum had more Ca(OH)2, less chemically combined water and no ettringite in the first day of hydration in comparison with the cement pastes with gypsum. The research indicates that calcined gypsum instead of gypsum accelerated the formation of early hydration products because the aluminate containing phases in clinker can not hydrate to form ettringite during the first day due to the low dissolution rate of calcined gypsum.
Ettringite
Aluminate
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The paper aims to study the influence of furized gypsum fly ash three constituent mixture subtle structure to performance by analyzing furized gypsum fly ash three constituent IR, SEM, X-ray phase and DTA. The results show that the reason why furized gypsum fly ash three constituent has the characteristics of high strength in the early stage and good endurance quality is that furized gypsum fly ash concrete has the double actived effect of alkali-activated and sulfate-activated. The development of sclerotium strength mainly relies on ettringite and hydrated calcium silicate gel. During the process of hydration, ettringite and CSH gel hydration increase continuously, hardened structure becomes dense and strength continues to increase.
Ettringite
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In this article the self-hardening structure of stone based on calcium sulfate formation is described. Increase of strength of gypsum is possible by additional reinforcing of a stone ettringite crystals. The form and character of the formed crystals is defined by size рН. Dependence рН from the maintenance of additives was investigated in work. The limiting factor of formation of crystals of an ettringite of a necessary look is the maintenance of an additive. In work gypsum composites with the improved physical-mechanical properties on the basis of the modifying complex are received and investigated.
Ettringite
Hardening (computing)
Limiting
Work hardening
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Ettringite
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Ettringite
Calcium aluminosilicate
Calcium silicate hydrate
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Ettringite
Sodium sulfate
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Calcium sulfate (e.g. gypsum) is the common set regulator in Portland cement. It has been shown that ground clinker can be set regulated by calcium salts other than gypsum, in particular calcium acetate, formate and nitrate. Rheology of the paste is improved when gypsum is replaced by other salts, probably due to less water binding and surface hydration products without the needle-like morphology of ettringite. In particular, for calcium nitrate, the cumulative hydration temperature is reduced, which allows for low-energy cement without changing clinker chemistry. Removing calcium sulfate all together may also allow heat curing or evolution of hydration heat in massive structures to exceed 70°C without risking delayed ettringite formation. These aspects have been elucidated by the experiments reported in this paper.
Ettringite
Calcium nitrate
Anhydrite
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Techniques have been developed for quantitative determination of elemental and crystalline composition of fly ash by X-ray fluorescence and diffraction. In addition to being fast, the methods are accurate and the knowledge provided from quantitative crystalline composition explains many of the behavioral characteristics of fly ash. From the study on one Class C, cementitious fly ash it was found that 23 percent of its composition is crystalline and that significant amounts of aluminous cements (tricalcium aluminate and calcium aluminum sulfate) are present. The cements explain this fly ash's capability for high strengths after hydration. A study involving continuous X-ray diffraction monitoring of hydration products showed that both Ettringite and monosulfoaluminate were formed; but when sufficient quantities of gypsum were introduced, Ettringite formation became dominant. Free calcium oxide was also found in this fly ash, and its behavior with water suggests a hard burned form, which is a feature of particular importance to use of fly ash in Portland cement concrete.
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Aluminate
Cementitious
Volcanic ash
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