• Resources Recycling
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• v.32 no.6
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• pp.10-17
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• 2023

Calcium silicate cement (CSC) is an environmentally sustainable, low-carbon cement and has garnered significant attention in recent studies. However, the pre-curing step required to activate the carbon dioxide reaction and to handle the sample. This study aimed to examine the viability of extending the application of CSC without pre-curing by enhancing initial strength by mixing calcium sulfoaluminate (CSA) fast-hardening cement into CSC. The investigation assessed changes in compression strength and Q-XRD mineral characteristics concerning variations in the mixing ratio of CSC and CSA fast-hardening cement within a carbon dioxide atmosphere. The compressive strength results indicated that the 3-day and 7-day strengths were 14.18 MPa and 22.98 MPa, respectively, under the 50% CSC condition, meeting the type 1 cement KS standard. Mineral characteristics analysis revealed an increase in calcite mineral, a byproduct of the carbon dioxide reaction, contributing to strength enhancement. Even after seven days, substantial quantities of unreacted rankinitene and pseudowollastonite were observed, as well as dicalcium silicate and yeelimite, which are hydrated minerals. This observation was confirmed the possibility of strength improvement after 7 days.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.631-637
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• 2002

This paper deals with hydration properties of the OPC with CSA-system expansive materials. In OPC using CSA, that was formed monosulfate for the main part. but In OPCs using CSA and gypsum, using CSA and gypsum and lime, that were formed ettringite for the main part. On the shrinkage ratio, the former is larger than the latter And CSA-system with gypsum and lime is smallest of all systems. According to dimension of shrinkage ratios are as follows; OPC using CSA only＞ OPC only＞ OPC using CSA and gypsum＞ OPC using CSA, gypsum and lime. And "R"s are 0.32, 0.37, 0.8, 0.8, 0.8 each others. In OPC with CSA-system expansive materials, we know that expansive properties were depend upon the value of "R". "R" means supplying quantities about demanding quantities for ettringite. In the case of expansive materials with CSA-system and lime, it is to be rich Ca(OH)$_2$ in the solution. so, it is formed small ettringite as the needle shapes. they are contribute to expansive.