Compressive strength, Bending and Fracture Characteristics of High Calcium Fly Ash Geopolymer Mortar Containing Portland Cement Cured at Ambient Temperature

Abstract

This article presented the compressive strength, modulus of rupture and fracture characteristics of high calcium fly ash (FA) geopolymer mortars containing Portland cement type I (PC) with different sodium hydroxide (NaOH) concentrations (6, 10 and 14 molars). PC was added at the dosages of 0, 5, 10 and 15 % by weight of solid powder binder. Sodium silicate (Na2SiO3) and NaOH solutions were used as the alkali activators. Na2SiO3 to NaOH ratio of 2.0, alkaline liquid to binder ratio of 0.60, sand to binder ratio of 1.00 and curing at ambient temperature were used for all mixtures. Test results indicated that the use of PC as additive enhanced compressive strength, modulus of rupture and fracture characteristics of high calcium fly ash geopolymer mortar and NaOH concentrations also had significant affect on these properties. The use of 10 % PC with 14M NaOH resulted in high calcium FA geopolymer mortar with improved modulus of rupture and fracture characteristics.