This paper investigates the cement hydration, and the slag reaction contributes to the compressive strengths of mortars mixed with ground river sand (GRS) and ground-granulated blast furnace (GGBF) slag with different particle sizes. GRS (inert material) and GGBF slag (reactive material) were ground separately until the median particle sizes of 32 ± 1, 18 ± 1, and 5 ± 1 micron and used to replace Portland cement (PC) in large amount (40–60%) by weight of the binder. The results showed that, at the early age, the compressive strength obtained from the cement hydration was higher than that obtained from the slag reaction. The results of compressive strength also indicated that the GGBF slag content and particle size play important roles in the slag reaction at the later ages, whereas cement hydration is more prominent at the early ages. Although the results could be expected from the use of GGBF slag to replace PC in mortar or concrete, this study had presented the values of the compressive strength along with ages and the finenesses of GGBF slag that contributed from cement hydration and from GGBF slag reaction.

This paper investigated the heat evolution of pastes containing inert and active materials with different particle sizes. Ground river sand was used as an inert material while ground granulated blast furnace (GGBF) slag was used as an active material. Ground river sand (GRS) and GGBF slag were ground to have the same particle size and were used separately as a replacement of Portland cement type I at rates of 50-70 % by weight of the binder. Heat evolution of pastes containing GRS and GGBF slag was measured using an isothermal conduction calorimeter up to 72 h. The results showed that GRS with different particle sizes had a slight effect on the heat evolution of pastes. GGBF slag with median particle size d50 of 4.4 µm and d50 of 17.8 µm had a small effect on the heat evolution of pastes during the first 24 h, and the pastes also had very low heat evolution for up to 72 h. At the same replacement rate of Portland cement, however, the heat evolution due to the slag reaction was slightly increased when the particle size of the GGBF slag was decreased. Finally, the higher is the cement replacement by GGBF slag, the higher is the slag reaction.