Upcycling waste plastics to fabricate lightweight, waterproof, and carbonation resistant cementitious materials with polymer-nano silica hybrids

Abstract

Most of the plastic waste, that rapidly and massively accumulates in the environment, does not get recycled but ends up in landfills and oceans causing pollution of water, soil, and air. This work presents an enhanced recycling scheme of waste plastics as aggregates in cementitious materials with ethylene-vinyl acetate (EVA) and nanosilica (nS) hybrids. 10% and 15% of natural sand were replaced by recycled waste plastic (RWP), and density, mechanical properties, capillary sorptivity and carbonation resistance of the RWP cementitious materials were evaluated. Results showed that not only the fabricated RWP specimens were 15%–18% lighter than the reference mixture but also the hybrid effect of EVA-nS was efficient in mitigating mechanical strength reductions and improving ductility up to 107%. Significant ameliorations of around 50% were observed in waterproof performance owing to the polymeric films created by EVA, while over 70% increase in carbonation resistance was noted owing to the filling and pozzolanic effects of nS. The replacement of natural sand with RWP by 10% would have the potential of reducing the annual sand consumption by 0.56–1 billion tons, which would substantially decrease the global CO2 emissions by 2.8–13.9 million tons annually. These findings pave a green path for upcycling RWPs in the sustainable, durable and lightweight construction material industry.