EFFECT OF GLASS FIBER ADDITION ON THE STRENGTH PROPERTIES AND PORE STRUCTURE OF FLY ASH BASED GEOPOLYMER COMPOSITES

This paper presents the results of an experimental program to determine the properties of glass fiber reinforced geopolymer mortar which is a mixture of fly ash, alkaline liquids, fine aggregates, and glass fibers. The effects of inclusion of glass fibers on density, compressive strength, splitting tensile strength, absorption and sorptivity of hardened geopolymer composite (GPC) was studied. Alkaline liquid to fly ash ratio was fixed as 0.33. NaOH and NaSiO3 solutions were used as alkaline liquids for activation of fly ash. The alkaline liquid combination ratio of 2.5:1 were used for Na2SiO3:NaOH. Glass fiber was added to the mixes in 0.2%, 0.4%, 0.6%, 0.8%, 1.0% and 1.2% by volume of mortar. A curing regime of 48 hours with 60 ˚C temperature was applied. The experimental results indicated that inclusion of the glass fibers resulted in a decrease in the workability, yet, an improvement in compressive strength and splitting tensile strength of fly ash based GPC was obtained by increasing the fiber content. However, the inclusion of glass fiber did not indicate a remarkable change in the water absorption and sorptivity of GPCs.