Valorization of industrial by-product gypsum for sustainable lightweight brick: Performance, microstructure and environmental safety assessments

Abstract

Sustainable development and the utilization of renewable resources are crucial for addressing environmental degradation and resource depletion, particularly in the construction industry. Bricks are one of the common construction materials, and their production has a substantial environmental impact. Phosphogypsum (PG), an industrial by-product gypsum with low recycling rates, is being explored as an alternative material for bricks. This study aims to conduct a comprehensive assessment of a novel lightweight PG-based brick (LPB), focusing on its engineering performance and environmental safety as a critical scientific evaluation prior to industrial application. The evaluation emphasizes the brick's service performance and safety characteristics. Additionally, the properties of the produced LPB were compared with three different types of commercial bricks, namely autoclaved aerated concrete (AAC) brick, cement sand brick (CSB), and red clay brick (RCB). The results demonstrate that LPB exhibits compressive strength (5.2 MPa) comparable to that of AAC bricks and CSB, along with good water resistance. Although LPB has a lower compressive strength than RCB, its lightweight nature (890 kg/m³) offers distinct advantages. Furthermore, the leachability of heavy metals from LPB, as well as the content of radionuclides in LPB, are below the limits outlined in GB 5085.3–2007 and GB 6566-2010, respectively. Therefore, LPB is suggested to be a viable brick option for non-load bearing applications in the construction industry without causing adverse environmental impacts. The research output can contribute to the promotion of sustainable building materials and the efficient utilization of PG resources.