A megaton-scale industrial demonstration study on hydrothermal mineralization enabled silty waste upcycling

Abstract

The continual large-scale urbanization and urban renewal in coastal cities of China have accumulated massive silty residue (SR) that may alter the coastal lines and always exerts high stresses to local environments. To meet China’s sustainable development policy, the need for green and high-efficient industrial treatments and reuse of SR is urgent. In this work, we may, for the first time, report a megaton-scale industrial project to upcycle low-quality SR and recycled aggregate (RA) to manufacture construction materials with hydrothermal mineralization (HM). In-situ pilot tests on five batches of SR-RA blocks were conducted. Results demonstrate that the produced blocks possess the compressive strengths of 11.4–15.8 MPa, densities of 1280–1430 kg/m3, porosities of 35–44%, CO2 emissions of 170.22–187.29 kg e-CO2/m3 and costs of 126.49–156.51 CNY/m3, comparable with or superior than the commercial blocks. The silica in SR could react with lime to produce tobermorite with stable pseudohexagonal plate under HM treatment, which improved the microstructure of the material. The findings validate the industrial practicability of upcycling low-quality SR and RA with HM for valuable construction block manufacture.