This study proposed a new binder as an alternative to conventional cement to reduce the heat of hydration in mass concrete elements. As a main cementitious material, low-heat cement (LHC) was considered, and then fly ash (FA), modified FA (MFA) by vibrator mill, and limestone powder (LP) were used as a partial replacement of LHC. The addition of FA delayed the induction period at the hydration heat curve and the maximum heat flow value (qmax) increased compared with the LHC based binder. As the proportion and fineness of the FA increased, the induction period of the hydration heat curve was extended, and the qmax increased. The hydration production of Ca(OH)2 was independent of the addition of FA or MFA up to an age of 7 days, beyond which the amount of Ca(OH)2 gradually decreased owing to their pozzolanic reaction. In the case of LP being used as a supplementary cementitious material, the induction period of the hydration heat curve was reduced by comparison with the case of LHC based binder, and monocarboaluminate was observed as a hydration product. The average pore size measured at an age of 28 days was smaller for LHC with FA or MFA than for 100% LHC.

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In order to use the high-volume slag cement as a construction materials, a proper activator which can improve the latent hydraulic reactivity is required. The dissolved aluminum silicon ions from ground granulated blast furnace slag (GGBFS) react with sulfate ions to form ettringite. The proper formation of ettringite can increase the early-age strength of high-volume GGBFS (80%) cement. The aim of this study is to investigate the hydration properties with sulfate activators (sodium sulfate, anhydrite). In this paper, the effects of Na 2 SO 4 and CaSO 4 on setting, compressive strength, hydration, micro-structure were investigated in high-volume GGBFS cement and compared with those of without activator. Test results indicate that equivalent SO 3 content of 3~5% improve the early-age hydration properties such as compressive strength, heat evolution rate, micro-pore structure in high-volume GGBFS cement.

High volume slag concrete is attracting new attention and are thought to have promising potential for industrial applications, partly due to the climate debate, but especially due to their very low heat of hydration and their good durability in chemically aggressive environments. However, High volume slag concretes tend to have slower strength development especially. In this study, the effect of anhydrite (CaSO4) on the mechanical and durability performance of high volume slag concrete were investigated. The main variables were anhydrite contents (0, 4, 6, 8, 10%). Test results show that 4~8% anhydrite concrete have improved engineering properties (hydration, compressive strength, shrinkage, creep, carbonation) as control concrete at early ages.

Material properties of geopolymer, whose the reaction is very complicated, have been influenced by chemical compositions and particle size distributions of fly ash, concentrations and types of alkali-activators and curing conditions such as temperatures and time. In this research, experiments with several variables such as curing temperatures, preset prior to the high temperature curing and high temperatures have been conducted in order to evaluate to investigate effects on the compressive strengths of geopolymer caused by curing condition. Experiment results were evaluated with compressive strengths and micro-structures such as SEM and MIP of geopolymer pastes. As a result, as higher curing temperature or longer preset time were applied to the pastes, higher compressive strengths were observed. However, compressive strengths of geopolymer pastes declined due to increases in macropores (>50 nm) under high temperatures elapsed after 24 hours. In this sense, it can be considered that strengths and microstructures of geopolymers depends on curing temperature and time.