Geopolymer Cement Based on Alkali Activated Slag

Abstract

The aim of this investigation is to prepare  geopolymer cement by mixing various amounts of granulated blast furnace slag (GBFS) with Fly ash (FA) and  cement kiln dust (CKD).  Seven blends  are  prepared  using 100 %  slag , 95% slag+5% CKD or fly ash ,  90% slag + 10% CKD or Fly ash  and  85% slag + 15% CKD or Fly ash . The dry mixes with the different mixing ratios are activated by the alkaline activator (AA) 6% sodium hydroxide solution  and 10% by volume liquid sodium silicate, the w/s ratio used is 0.24.  The pastes are moulded  into 1 inch cubic moulds and left within the moulds at 100% relative humidity for 24 hrs, then demoulded  and cured under tap water for 1,3,7,28,90 and 180 days. At each hydration time, compressive strength, combined  water , bulk density , total porosity are determined . X-ray diffraction measurements showed CSH as the main  hydration constituent of the geopolymer structure being amorphous and glass-like. The results indicate that the mix containing 85% slag + 15% fly ash give the best physico chemical and mechanical properties of geopolymer cement .