Effects of types and surface areas of activated materials on compressive strength of GGBS cement

Abstract

This study focused on the effects of changing the types and surface areas (Sa) of activated materials on the compressive strength of Ground Granulated Blast-furnace Slag (GGBS) cement (GGBS > 60%). This study is divided into two parts. The first part involves the selection of activated materials. The compressive strength results show that gypsum improves the early strength of GGBS cement more effectively that does sodium silicate or NaOH. The gypsum activators increase GGBS activity through sulfates, which generates ettringites and C-S-H to increase compressive strength. Chemical analysis shows that the SO₃ in GGBS cement has more stable compressive strength at 6%–8%. The second part of this study is on the influence of Sa. Gypsum was used as a strength activator. The SO₃ in GGBS cement was controlled at 6.5%±0.5%, and Sa was adjusted as the variable. Linear regression analysis shows that the change in GGBS cement Sa (M_Sa) is positively correlated with compressive strength. The M_Sa can be estimated according to the Sa and quantity of ingredients used for the study results (cement, GGBS, and gypsum). The compressive strengths of GGBS cement at various curing ages can be predicted with M_Sa.