Effect of polyethylene powder and heating treatment on the microstructure and hardened properties of foam concrete

To tackle the energy consumption issue and meet the energy-efficiency building requirement, this study proposes a method by incorporating polyethylene (PE) powder as a multi-function and low-cost construction material in the foam concrete to enhance the thermal insulation. The effects of heating treatment and dosages of PE powder on the dry density, compressive strength, water absorption, thermal conductivity and microstructure of foam concrete were investigated. The pore structure and morphology were examined using Image-Pro-Plus software, electron microscope and SEM-EDS. Results indicate that the dry density and compressive strength of foam concrete generally decreased, while the water absorption overall increased with higher dosage of PE powder. Thermal conductivity of foam concrete containing PE powder without heating treatment exhibited a rising trend with the increase of dosage, while that of foam concrete prepared with the PE powder was greatly inhibited by heating treatment. Both the average roundness of pores and the porosity of foam concrete increased with the incorporation of PE powder, but the smaller effective pore size in the foam concrete with heating treatment was significant. The PE membrane coated on the pore wall and clogged the pore structure, which was verified by SEM-EDS analysis on the microstructure of foam concrete after heating treatment.