Performance of lightweight foamed concrete partially replacing cement with industrial and agricultural wastes: Microstructure characteristics, thermal conductivity, and hardened properties

The production of eco-friendly concrete has been made possible by reusing agricultural and industrial wastes. This paper presents an experimental investigation of the characteristics of lightweight foamed concrete (LWF) produced from a protein-based foaming agent and including granulated blast furnace slag (GGBS), fly ash (FA), rice husk ash (RHA) and palm oil fuel ash (POFA) at various substitution levels (0, 10 %, 20 %, 30 %, 40 %, 50 %, and 60 %) with cement. By executing a slump test, the fresh characteristics of mixes were assessed. In addition, a total of 25 different LWF mixtures were produced and tested for their porosity, bulk density, compressive strength, bending strength, splitting tensile strength, water absorption, ultrasonic pulse velocity (UPV), and thermal conductivity. To elucidate the causes for the experimental findings acquired, microstructural analysis was also performed. The findings indicate that the GGBS, FA, RHA, and POFA ratios of the LWFs increased due to a reduction in slump, porosity, water absorption, bulk density, and thermal conductivity up to 40 % GGBS, 30 % FA, 20 % RHA, and 30 % POFA. However, the compressive strength, bending strength, splitting tensile strength, UPV were raised up to 40 % GGBS, 30 % FA, 20 % RHA and 30 % POFA as substitution for cement. LWF containing 40 % GBS as a cement substitution also demonstrate larger compressive strength, bending strength, splitting tensile strength, and ultrasonic pulse velocity in comparison with the control, 30 % FA, 20 % RHA, and 30 % POFA LWF. The findings are promising and reveal a major opportunity for developing eco-friendly LWF by partially substituting cement with GGBS and FA industrial by-product material, RHA and POFA agricultural waste materials as well.