Contribution to the reinforcement of cement composites using aggregates from industrial windshield waste

The excessive extraction of raw materials for aggregate and cement production for developing sustainable concrete results in significant environmental issues. Automotive windshield waste (WGA) is increasing daily, contributing significantly to landfills due to a rapidly growing population and limited recycling options. This research investigates the use of WGA as a substitute for fine aggregates combined with blast furnace slag (BFS) as a filler to produce a new eco-friendly self-compacting sand concrete (SCSC). For this, eleven SCSC mixtures were prepared at a constant cement and BFS content of 400 kg/m³ and 200 kg/m³, respectively. The water-to-powder ratio was kept constant at 0.44. The superplasticizer-to-cement ratio was selected for each mix to improve the fresh SCSC flowability and homogeneity. The sand was substituted in volume with the WGA at a proportion of 10 to 100% with a step of 10%. The obtained results show the feasibility of producing high-performance SCSC by completely replacing natural sand with WGA, without impairing the concrete’s workability, mechanical, and durability properties. SCSC with 20% WGA substitution was found to be optimum with compressive and flexural strength 80% and 50% higher than the reference concrete, respectively. Furthermore, the use of up to 100% WGA showed high-quality concrete with more than 80 MPa compressive strengths, a significant reduction in water absorption and porosity, a denser microstructure, and a stronger interfacial transition zone (ITZ).