Recycled coarse aggregates from precast plant and building demolitions: environmental and economic modeling through stochastic simulations

Abstract

Concrete is one of the most widely used construction materials in the world. However, its sustainability is currently being challenged by the depletion of natural resources necessary to produce it (mainly due to the mining of aggregates) and the use of landfill space for its final disposition after service use. At the same time, the need for faster construction has encouraged the utilization of precast concrete structures, including pre-stressed elements. Recycled concrete aggregates could make the fabrication of concrete more sustainable; several studies demonstrate the technical feasibility of recycled concrete aggregates in Portland cement concrete for structural use. However, the sustainability of recycled concrete aggregates needs more reliable methodologies to assess it. This paper presents a stochastic simulation model of the precast fabrication process that considers obtaining materials, materials transportation, and precast elements production to evaluate the use of water, generation of CO2 emissions, and costs incurred when using natural coarse aggregates versus recycled concrete coarse aggregates from several sources. The model is based on data from companies in the United States, Canada, and Chile. The results show that replacing natural coarse aggregates with recycled concrete coarse aggregates reduces CO2 emissions and costs for the production of precast concrete elements, compared with the conventional system. However, water consumption is increased when recycled concrete coarse aggregates is used. Therefore, this research shows that the use of recycled concrete coarse aggregates for precast plants can be beneficial in terms of CO2 emissions and cost in contexts where water is not a scarce resource.