Influence of wastepaper sludge ash as partial cement replacement on the properties of lightweight foamed concrete

This study focused on the effect of using wastepaper sludge ash (WPSA) as a partial substitute for cement in the production of lightweight foamed concrete (LFC). The LFC was produced with a constant dry density of 1350 kg/m3 by controlling the foam content. In this study, six mixtures of LFC were produced using WPSA as a partial substitute of 0%, 5%, 10%, 15%, 20% and 25% of the cement mass. Setting time, spreading ability and density tests were performed immediately after the mixing process to evaluate the fresh LFC properties. Meanwhile, the compressive strength, flexural strength, cleavage tensile strength and modulus of the elasticity tests were performed at test ages 7, 14 and 28 days to evaluate the mechanical properties. Water absorption, capillary absorption, gas permeability, porosity and pore distribution were performed to evaluate the transport properties. Furthermore, SEM evaluation was performed to evaluate the microstructure. The inclusion of WPSA as a 15% partial cement replacement achieved the highest mechanical properties. The compressive strength was 11.2 MPa, the flexural strength was 2.61 MPa, the tensile strength was 1.72 MPa, and the elastic modulus was 3.253 GPa. Inclusion of WPSA as a partial substitute for cement with 25% led to the best transport properties by having the lowest water absorption and porosity by 17.4% and 37.75%, respectively.