Mechanical Properties of Geopolymer Concrete Exposed to Combustion

This paper presents the change of material properties, such as decreasing of the compressive strength, splitting tensile strength, and porosity. The main objective of this paper is to analyze the mechanical properties of fly ash-based geopolymer concrete after being exposed to high temperature. The 28th-day test specimens were burned for one hour at specified temperature variation of 200 degrees C, 400 degrees C, 600 degrees C, and 800 degrees C. Ordinary Portland Cement (OPC) concrete was used as a comparison. After burning at 400 degrees C, the compressive strength of geopolymer concrete was surprisingly increased up to 27% of its normal strength. On the other hand, the compressive strength of OPC concrete decreased 67% from its normal strength. The splitting tensile strength of geopolymer concrete also decreased at the range of 50-70%. The porosity of concrete has a sufficient effect to compressive strength and splitting strength. X-Ray Diffraction (XRD) test of geopolymer concrete at temperature 400 degrees C until 600 degrees C showed some minerals change. Geopolymer concrete is proved to have better fire resistance compares to Portland Cement Concrete.