Thermal and mechanical performance of lightweight geopolymer concrete with pumice aggregate

Abstract

This study aims to prepare and assess the mechanical characteristics of fly ash (FA)‐based lightweight geopolymer concrete (LWGPC) utilizing pumice as a coarse aggregate. A comprehensive set of 16 LWGPC mixtures were synthesized. The first twelve mixtures produced with varying alkaline to FA ratio and varying proportions of coarse aggregates. The mixture proportion that has given the highest compressive strength (CS), was selected to create four other LWGPC mixes with water‐to‐solid ratios (w/s) ranging from 0.17 to 0.23. Fresh and mechanical properties as well as thermal conductivity (TC) of the LWGPC samples were examined. The experimental findings indicate an inverse relationship between the w/s ratio and mechanical properties of LWGPC samples. Notably, the mechanical properties attain their highest values at the lowest w/s ratio, primarily attributed to reduced porosity and higher concentration of alkali solution in the mixtures with lesser water content. The LWGPC achieved highest CS of 13 MPa, modulus of elasticity (ME) of 8.8 GPa, flexural strength (FS) of 2.2 MPa, and tensile splitting strength (TSS) of 1.64 MPa. The oven dry density (ODD) and TC values ranged from 1746 to 1815 kg/m3 and 0.119 to 0.131 W/m K, respectively. A low‐cost and eco‐friendly novel lightweight concrete composition with low TC was developed.