(1.School of Architecture Engineering, Zhejiang University, Hangzhou 310058, China) (2.School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China) (3.School of Materials Science and Engineering, Tongji University, Shanghai 201804, China)
In order to understand the affect factors of weathering resistance of foam concrete cast-in-place roof insulation system, five accelerated weathering tests of foam concrete were carried out, including humid-heat cycle, dry-wet cycle, high-low temperature cycle, freeze-thaw cycle and multi-field coupling cycle. By analyzing the evolution rule of its pore structure, volume water absorption and thermal conductivity, the weathering resistance of foam concrete was revealed. The results show that the volume water absorption of foam concrete increases only 1.77% and its thermal conductivity decreases by 6% after 112 humid-heat cycles. After 112 dry-wet cycles, the volume water absorption of foam concrete increases from 20.64% to 25.63%, and its thermal conductivity increases from 0.0724 to 0.0836 W/(m·K), which has increased by 15.47%. After 112 high-low temperature cycles, the volume water absorption of foam concrete increases from 21.13% to 2514%, and its thermal conductivity has increased by 6.68%. After 112 freeze-thaw cycles, the volume water absorption of foam concrete increases from 23.97% to 29.38%. Meanwhile, its thermal conductivity increases from 0.0789 to 0.0980 W/(m·K), which has increased by 24.21%. After 112 multi-field coupling cycles, the volume water absorption of foam concrete increases from 14.12% to 16.88%. Its thermal conductivity has increased by 18.06%, which increases from 0.0720 to 0.0850 W/(m·K). Through four kinds of accelerated weathering tests, which are dry-wet cycle, high-low temperature cycle, freeze-thaw cycle and multi-field coupling cycle, the pore structures in foam concrete has broken and collapsed seriously. Furthermore, the foam concrete sheet has cracked and collapsed. Therefore, the thermal insulation performance of foam concrete decreases and its volume water absorption increases. The foam concrete shows good performance in humidheat cycle test. During this process, the pore structure, volume water absorption and thermal conductivity of foam concrete have no significant variation.