Effect of source materials, additives on the mechanical properties and durability of fly ash and fly ash-slag geopolymer mortar: A review

Abstract

Geopolymer is a sub-class of alkali activated materials composed of base materials containing aluminosilicates which can be used for construction with reduced environmental impact by utilisation of waste material leading to economical construction. This study reviews the properties of fly ash and fly ash-slag geopolymer mortar including microstructural properties, fresh properties such as setting time and workability, hardened properties such as compressive strength and tensile strength and durability properties (thermal resistance, shrinkage, acid resistance, chloride resistance, sulphate resistance). The effect of types of alkaline solutions, its concentration, and combination of different types of alkaline activators, fine aggregate to binder ratio, alkaline solution to binder ratio, curing temperature and curing duration, and presence of different types of superplasticizers are discussed. The study also reviews the effect of different additives such as silica fume, alccofine, quartz powder, alumina, epoxy, bio-additives, different types of fibres, nano-materials in fly ash and fly ash-slag geopolymer mortar. The present study carried out elaborate discussion of the effect of mix proportioning on fresh, hardened and durability properties of fly ash geopolymer and fly ash-slag geopolymer mortar. The study summarises the common findings from the reviewed research papers.