EFFECT OF EXPOSURE TO ELEVATED TEMPERATURES ON GEOPOLYMER CONCRETE PROPERTIES

Researchers head for replacing cement in concrete with materials with lower CO2 emissions and energy demand. Geopolymer concrete is environmental friendly concrete based on industrial solid wastes and by products just like Ground Granulated Blast Furnace Slag (GGBS) and Fly ash (FA). This research aims to produce geopolymer concrete using local available materials in Egypt and suits the structural purposes. The research investigates also the residual mechanical characteristics and microstructure of geopolymer concrete after exposure to elevated temperatures. Specimens of four cement and geoplymer concrete mixes with different intended compressive strengths, 25 MPa and 40 MPa, were produced. Concrete specimens were tested at the ambient temperature and at elevated temperatures of 300⁰C and 500⁰C for exposure durations of 60 and 120 minutes. Comparisons were carried out between the properties of geopolymer and cement concrete before and after the exposure to the elevated temperatures. The results showed that, it is possible to produce geopolymer concrete with the target compressive strength based on the local GGBS as source materials. Splitting tensile strength and modulus of elasticity of geopolymer concrete were lower than the counterpart of cement concrete. Exposure to elevated temperature decreased the mechanical properties of both types of concrete. However, cement concrete showed better behavior at elevated temperature than geopolymer concrete.