Mechanical properties of fly ash-based geopolymer concrete using variation in maximum size of coarse aggregate

Abstract

The aim of this research was to study the mechanical properties (compressive strength and splitting-tensile strength) of fly ash-based geopolymer concrete using variation in the maximum size of coarse aggregate. The mode of study was laboratory research. Fly ash obtained from Asam-Asam Steam Power Plant, South Kalimantan, Indonesia. The maximum size of coarse aggregate was 10 mm, 20 mm and 30 mm. The geopolymer concrete proportion divided into 3 different mixtures and each contained 400 kg/m3 of fly ash. The alkaline activator used as sodium silicate and 10M sodium hydroxide in the ratio 2:1. The ratio of alkaline activator to fly ash was 0.4. Cylindrical specimens (size 100 mm x 200 mm) counted 10 pieces for each mixture proportion and cured at ambient condition. The test result showed that average of compressive strengths and splitting-tensile strengths for specimens with 10 mm, 20 mm, and 30 mm maximum size of aggregate at the age of 21 days were 11.04 MPa and 6.12 MPa, 10.82 MPa and 5.22 MPa, 10.06 MPa and 4.84 MPa respectively. In conclusion, the greater the maximum size of coarse aggregate, the smaller the value of compressive strength and splitting-tensile strength.