Characterization of Alkali-Activated Nonwood Biomass Ash–Based Geopolymer Concrete

Abstract

The combustion ash of a common nonwood biomass (wheat straw) was evaluated for value-added use in production of geopolymer concrete where alkali aluminosilicate hydrates are the primary binder constituents. The wheat straw ash was supplemented with other raw materials in order to achieve a desired chemical balance. The binder composition that performed well in experimental work comprised wheat straw ash:coal fly ash:metakaolin:gypsum at 0.50:0.25:0.25:0.05 weight ratios. The wheat straw ash–based concrete as well as a control portland cement concrete were subjected to a comprehensive experimental investigation. The workability, set time, compressive strength, residual compressive strength after immersion in boiling water, flexural strength, density, moisture absorption, voids content, capillary sorptivity, and acid and fire resistance of concrete materials were evaluated. The experimental results indicated that the nonwood biomass ash–based geopolymer concrete materials with proper binder formulation can provide desired mechanical attributes, moisture barrier qualities, durability, and fire resistance when compared with normal portland cement concrete.