Durability performance of low calcium Flyash-Based geopolymer concrete

Abstract

This investigation aims to systematically evaluate the durability performance of 30 MPa grade of low calcium fly ash-based geopolymer concrete. The geopolymer concrete with fly ash as binder is manufactured using an alkaline activator solution (of 14 Molar and Na2Sio3/NaOH ratio of 2.5). The results were also compared with the Portland cement concrete of similar grade. The concrete samples were subjected to water absorption, water permeability, sorptivity, acid resistance, sulphate resistance, and rapid chloride penetration tests. Water absorption study findings revealed less water absorption by low calcium fly ash-based geopolymer concrete than Portland cement concrete. Also, the water permeability tests on geopolymer concrete indicated lower water penetration depth compared to Portland cement concrete. Sorptivity test results depict lower sorptivity by geopolymer concrete over ordinary Portland cement concrete. Geopolymer concrete shows better acid resistance and sulphate resistance performance than Portland cement concrete in terms of residual compressive strength. Rapid chloride penetration test results indicated moderate chloride penetrability of geopolymer concrete and low chloride penetrability by Portland cement concrete. In general, low calcium fly ash based geopolymer concrete outperformed Portland cement concrete in most durability indices, which led to the conclusion that low calcium fly ash based geopolymer concrete durability performance was superior to that of concrete of a similar grade made of Portland cement concrete.