Thermal Performance of Lightweight Concrete Made of Sewage Sludge Ash

摘要

In this study, sewage sludge ash is used as the main ingredient, to be mixed with Portland cement and a foaming agent to produce lightweight construction materials, which meets the environmental protection requirements for energy saving and heat insulation. Through burning tests, the sludge ash lightweight concrete is studied at both fixed temperatures and different thermal degradation levels, to determine the influence on the engineering properties and the microstructure at high temperatures of changing the amount of sewage sludge ash, the foaming agent, and the water to solid ratio. The tests show that if bumt under 1,000°C, the properties and microstructure of sewage sludge ash lightweight concrete will be affected by the hydration of the paste. However, if bumt over 1,000°C, these are affected by the sintering effects of the paste. If the buming temperature is lower than 600°C, the bulk density will not change observably. When the buming temperature reaches 800°C, the volume shrinkage rate will grow by 2.2 to 2.6 times, but in appearance, the specimen appears shrank evenly and fused. Under a high temperature, the compressive strength increases positively with the increase of sewage sludge ash used, and more sludge ash will slow down specimen cracking and enhance the strength. Moreover, after being bumt at high temperatures, the total porosity will decrease and the capillary pore volume will increase, but the gel pores will decrease. The properties of the sewage sludge ash lightweight concrete become more stable after being bumt at a high temperature, which indicates that the material should be good to use, both at normal temperatures and after being treated at high temperatures.