Studies on compressive strength of sand stabilized by alkali-activated ground bottom ash and cured at the ambient conditions

Abstract

Bottom ash is a by-product generated during the coal combustion of thermal power plant. Bottom ash-based geopolymer has been reported as a promising substitute of cement in concrete. In this study, bottom ash collected from Honam Coal Power Plant was ground to be used as a soil stabilizer. Sodium hydroxide solution (NaOH) with different molarity concentration and sodium silicate solution (Na2SiO3) were added to enhance the polymerization reaction of ground bottom ash. The effects of water/ground bottom ash, Na2SiO3/NaOH ratio and concentration of NaOH solution on the unconfined compressive strength of sand mixture at the ambient curing conditions were investigated. The results indicated that ground bottom ash can be utilized to stabilize sand as a main binder at the ambient curing conditions. In particular, with the 4 M concentration of sodium hydroxide solution, the Na2SiO3/NaOH ratio of 1.5 and the water/binder ratio of 0.35, the highest compressive strength obtained at 28 days was around 9 MPa. The compressive strength of sand mixture increased with an increase of NaOH solution concentration and the ratio of Na2SiO3/NaOH, however, it dramatically decreased with the addition of water to the mixture.