Effect of GGBS & Fly ash aggregates on properties of geopolymer concrete

Abstract

The paper deals with the influence of Ground Granulated Blast Furnace Slag (GGBS) and concentration of sodium hydroxide (NaOH) solution on the physical and mechanical properties of the Geopolymer Concrete (GPC) with fly ash aggregates. The fly ash aggregates were prepared using class C fly ash by adopting pelletization technique without adding any binders. Two types of curing techniques were adopted for aggregates i.e water curing and chemical curing (using NaOH solution). These two types of cured aggregates are called as Water Cured Aggregate (WCA) and Chemical Cured Aggregates (CCA). The tests like compressive strength, water absorption and specific gravity were carried out on the cured aggregates. The strength of CCA was 64.93%, 49.03% more when compared to WCA for 7 and 28 days curing and the water absorption of CCA were 4.0% for 7 days and 4.2% for 28 days. The GPC mixes were cast with CCA and WCA at 0% and 30% replacement of fly ash(class F) by GGBS with different concentrations of NaOH solutions (8M, 10M, 12M). It was observed that the GPC mixes with CCA and WCA at 30% GGBS with 12M NaOH concentration attained maximum compressive strengths of 64.14 MPa and 42.13 MPa cured at room temperature. Among the GPC specimens it is observed that the GPC mixes with CCA had better workability and bonding at the interfacial transition zone.