Physico-mechanical, thermal insulation properties, and microstructure of geopolymer foam concrete containing sawdust ash and egg shell

Abstract

Recently, energy conservation through building thermal insulation has gained significant importance in solving sustainability-related issues. In this context, this study investigates the potential for manufacturing geopolymer foam concrete (GFC) containing eggshell powder (ESP) and sawdust ash (SDA) using aluminium (Al) powder as a foaming agent. The role of Al-powder percentages on the mechanical and thermal properties of GFC was thoroughly investigated. The effect of ESP and SDA incorporation as partial replacements of precursors (from 0 to 20 %) on the thermal properties, durability, and microstructure of GFCs were also discussed. The experimental findings demonstrate that the bulk density and compressive strength of GFC with different Al-powder contents ranged between 1928 and 1798 kg/m3 and 17.45 and 9.37 MPa, respectively. The SEM images and MIP tests show that foams with different numbers of micro- and macropores are formed in GFCs. The ESP-based GFC had an apparent porosity range of 13.09 %–10.29 % and a bulk density range of 1823 to 1713 kg/m3. The SDA-based GFC had an apparent porosity range of 14.21 %–12.96 % and a bulk density range of 1834 to 1807.8 kg/m3. It was found that the 10 % ESP and 5 %, SDA mixtures enhanced the strength by 16.54 % and 4.45 %, respectively, compared to the control mix. The thermal conductivity, thermal diffusivity, and specific heat of 10 % ESP-mixture and 5 % SDA-mixture were 1.237 and 1.167 W/(mK), 0.795 and 0.922 mm2/S, and 1.556 and 1.266 MJ/m3K, respectively. Finally, the residual strength and microstructure investigations demonstrate that ESP-based GFCs have more stability than SDA-based GFCs and the control mix when subjected to elevated temperatures.