Recycling of magnesium oxychloride cement: Application of crushed MOC waste as a filler in the next-generation MOC composites

This study deals with magnesium oxychloride- (MOC-) based construction composites in which, a filler formed from end-of-life MOC-based composite recyclate is used as a partial or full replacement of standard quartz sand filler. The developed composites pose as a highly environmentally sustainable alternative to Portland cement (PC), which has dominated the global construction sector, largely due to its unique properties and adaptability to various conditions. As the PC industry is a major contributor to greenhouse gas emissions, it is ultimately necessary to find a suitable alternative. In our study, we demonstrated that the proposed composite, even with a very high content of the MOC-based recyclate performs well concerning its mechanical parameters evidenced by compressive strength exceeding 64 MPa. The developed composites also yield a low water absorption of about 3.3 wt% and even when exposed to the harsh environment of 95 % RH for 7 days, their softening coefficient reaches values higher than 85 %. The acquired material parameters of the prepared composites make them suitable for application in the production of construction materials with high mechanical strength and acceptable resistance to the action of moisture. The approach which was taken, where MOC-based construction waste can be fully reutilized in the next generation of MOC composites as a filler represents a very promising route for the development of waste-free and CO 2 -neutral technology . • MOC recyclate used as filler in magnesium oxychloride cement-based composite. • Replacement of silica sand up to 100 % by volume – sawing of natural resources. • High compactness and mechanical strength of the hardened MOC composites. • Low water absorption and sufficient moisture resistance. • Route for the development of waste-free and CO 2 -neutral construction materials.