Investigation of Geopolymer Mortar and Concrete Under High Temperature

Fly ash-based Geopolymer concrete is a new material that does not need the presence of Portland cement as a binder and the role of Portland cement is replaced by low calcium fly ash. This material is being studied extensively as a greener substitute for OPC concrete in some applications. Geopolymers are generally believed to provide good fire resistance due to their ceramic-like properties. This paper presents the results of a study on the effect of elevated temperatures on geopolymer mortar and concrete for different types of coarse and fine aggregates. Also these results are compared with the OPC concrete of M20 grade. The geopolymer was synthesized with fly ash, sodium silicate and sodium hydroxide solutions. Coarse aggregates used for concrete specimens are basalt and granite aggregates while natural river sand and crushed sand are used as fine aggregates for mortar specimens. The study identifies that the geopolymer concrete gives better performance than OPC concrete, in both ambient and elevated temperatures. In case of concrete specimens granite aggregates have better strength than basalt aggregates while for mortar crushed sand has better strength than natural river sand. Also, loss in compressive strength and weight due to thermal changes is less in geopolymer concrete as compared to OPC concrete.