Influence of recycled powder derived from waste concrete on mechanical and thermal properties of foam concrete

To advance the reusing of waste concrete from construction and demolition waste, the recycled powder (RP) derived from waste concrete was used as the supplementary cementitious material to prepare foam concrete in this study. The influence of different replacement ratios of RP and cement types on the properties of foam concrete was investigated. A series of micro and macro tests were also carried out. The results show that the incorporation of RP had little impact on the wet and dry density. While the compressive strength overall decreased with the increase of RP content. The incorporation of RP could reduce the thermal conductivity of foam concrete, and it could reach the lowest when the RP replacement ratio is 30%. The maximum reduction of compressive strength and thermal conductivity of recycled powder foam concrete was 59.9% and 22.5%, respectively, which was observed in recycled powder foam concrete with sulphoaluminate cement. The porosity and maximum pore size of foam concrete gradually increased with the increase of RP content. It can be concluded that RP is suitable for the production of foam concrete and the improvement of insulating properties. • Effect of recycled powder and cement types on properties of foam concrete is explored. • 30 wt.% of recycled powder largely decreases thermal conductivity of foam concrete with a maximum reduction of 22.5%. • AFt and AH 3 content decrease with the addition of recycled powder. • Porosity and maximum pore size increase with an increase in recycled powder content.