Deformational behaviour of fly-ash based geopolymer concrete at temperatures of up to 150°c

Assistant Professor, University of Sharjah, Sharjah, UAE

^* Corresponding author: mjunaid@sharjah.ac.ae

Abstract

The use of Geopolymer Concrete (GP^*C) has been on the rise over the last few decades owing to its lower carbon emissions as compared to Ordinary Portland Cement Concrete (OPC). Recent research has also established the superior thermal properties of GPC and makes it an ideal construction material for specialized application. However, the deformational behaviour of GPC at elevated temperatures has not fully understood. If GPC is to be used as a main stream construction material for specialized applications, the exact deformational behaviour of the material under thermal loading needs to be investigated. This paper looks into the deformational characteristics of GPC (with natural crushed siliceous aggregates) when dry heated up to 150°C at near zero loading. The deformations recorded using a clip-on extensometer are used to determine the strains developed in the GPC samples due to thermal loads. Coefficient of thermal expansion (CTE) for the tested GPC samples was found and was comparable to OPC concrete at the tested temperatures. Between ambient (20°C) and 80°C the CTE for GPC was determined to be between 10.3-10.9x10⁻⁶mm/mm/°C which is similar to OPC concretes. CTE for temperatures between 80°C and 150°C was determined to be 9.3-10.0x10⁻⁶ mm/mm/°C. First heating cycles resulted in much lower CTE which may be due to the presence of evaporable water in the samples. Like OPC, GPC is a non-homogeneous material and the variation in the materials between samples account for the slight variation in the CTE values determined.