Investigation of the water resistance of non-sintered wrap-shell lightweight aggregates with high content solid waste and its application in water permeable bricks

Non-sintered solid waste lightweight aggregates can be used as building materials. However, its active hydration performance has brought challenges to its application. In this study, non-sintered waterproof solid waste wrapshell lightweight aggregates (W-SWSLAs) were prepared from dredged sediments, steel slag, and other solid waste materials, and activator and waterproof agent were also added. The shell phase of W-SWSLAs was treated with inorganic aluminum salt waterproof agent (IWA) and silicone waterproof agent (SWA), respectively, to investigate the effects of different kinds and dosages of waterproof agents on the properties of the bearing capacity of single grain and water resistance. The performance of W-SWSLAs was assessed from the environmental, physicochemical and mechanical perspectives, respectively. In addition, its application in water permeable bricks was also studied. The results showed that when the addition amount of SWA was 0.08%, it could reach a good balance between the water resistance and mechanical performance of W-SWSLAs. The leaching values of pollutants were well below the limit value set out in the legislation. The water absorption rate, cylinder compression strength and softening coefficient of W-SWSLAs were 8.73%, 20.35 MPa, and 0.84, respectively. The permeability coefficient of water permeable bricks prepared from W-SWSLAs (W-SWSLAPB) was 0.022 cm/s, and the strength loss rate was 10.4% after 25 freeze-thaw cycles, which all met the current Chinese National Standards. The production of W-SWSLAs, whose solid waste content is 95.17 wt%, provides an eco-friendlier approach to converting hazardous and industrial solid waste into high value-added materials.