Evaluation of thermal conductivity, mechanical and transport properties of lightweight aggregate foamed geopolymer concrete

•The usage of industrial by-products FA and POFA as binder in geopolymer concrete.•Structural grade geopolymer foamed concrete using lightweight coarse aggregate, OPS.•Thermal conductivity of OPSFGC13 was 48% lower than the conventional brick.•Strength to density ratio of the OPSFGC was 54% higher than the corresponding NWC. Energy efficiency is the predominant criterion in green building indices, which, in turn, contributes to sustainable development. One of the materials commonly used in the insulation of buildings is foamed concrete. This investigation presents the main objective of the experimental results concerning the thermal conductivity of oil palm shell foamed geopolymer concrete (OPSFGC), utilizing waste materials such as low-calcium fly ash (FA) and palm oil fuel ash (POFA) as cementitious materials, and oil palm shell (OPS) as lightweight coarse aggregate (LWA). Three OPSFGC mixtures with densities of 1300, 1500 and 1700kg/m3 were prepared using an artificial foaming agent; a control mix without foam and conventional materials – block and brick – were used for comparison. The test results on the mechanical and transport properties are also discussed. The thermal conductivity of OPSFGC13 of about 0.47W/mK was 22% and 48% lower than the conventional wall materials, block and brick, respectively. OPSFGC, with a density of 1300 and 1500kg/m3, could be categorized as structural and insulating concrete, Class-II, whereas OPSFGC with a density of 1700kg/m3 is classified as Class-I structural grade concrete with a compressive strength and thermal conductivity of about 30MPa and 0.58W/mK, respectively.