Developing geopolymer concrete by using cold-bonded fly ash aggregate, nano-silica, and steel fiber

This experimental study presents the effect of nano-silica and steel fiber on the transport properties and compressive strength of alkali-activated slag/fly ash concrete incorporated cold-bonded fly ash aggregate. In order to reduce energy consumption and provide environmental impact, the cold-bonded process was used to manufacture cold-bonded fly ash aggregate. Twenty four geopolymer concrete mixtures incorporated cold-bonded fly ash aggregate, nano-silica, and steel fiber were produced with sodium hydroxide concentration of 12 M and cured at ambient temperature. Transport properties of geopolymers were examined through water penetration, water sorptivity, and gas permeability at 28 and 90 days. Results indicate that geopolymer concrete incorporated cold-bonded fly ash aggregate can be produced with compressive strength as high as 28.23 and 36.62 at 28 and 90 days, respectively. However, 2% nano-silica and 1% steel fiber volume fraction were the most significant parameters that caused remarkable improvement of investigated properties. Moreover, the incorporation of waste materials in aggregate and geopolymer concrete production can alleviate environmental problems.