Lightweight geopolymers made of integrated gasification combined cycle (IGCC) slags and Si sludges exhibit an unusual breakdown, known as dentable characteristics. In this study, dentable characteristics of lightweight geopolymers were investigated under different curing and aging conditions. The relationship between these conditions and dentable characteristics was determined by measuring compressive strength, conducting XRD and FT-IR, and by optical microscopic observations of pore size, distribution, and shape. Dentable characteristics cannot be simply controlled by changing the curing and aging conditions. Homogeneous pore distribution, size, and shape by extra mixing did not enhance the dentable characteristics. Although the moisture and Si content of the geopolymer would control the dentable characteristic in some measure, aging conditions were found to be the most important effect on the dentable characteristics and stability of geopolymers in water.

Keywords: Geopolymer, Dentable characteristics, IGCC slag, Si sludge, Curing, Aging