Towards an eco-efficient ready mix-concrete industry: Advances and opportunities. A study of the Metropolitan Region of Buenos Aires

There is a growing demand in Latin America and the Caribbean for building materials to satisfy the need for adequate housing and infrastructure in urban areas. This paper examines the consumption of materials and environmental impact of ready-mix concrete produced in the Metropolitan Region of Buenos Aires in a certain period of time. Material flow analysis and life cycle assessment (LCA) were performed. The average composition concrete was estimated by means of surveys conducted with ready-mix concrete producers. The material efficiency (ME), CO2 equivalent emissions (ECO(2)eq), materials and energy use were used as environmental indicators. Feasible impact reduction strategies and their influence on the LCA were also explored. 7.16 Mt of materials were required to produce 2,604,862 m(3) of ready-mix concrete, within 99.1% corresponded to raw materials, while 0.9% corresponded to secondary raw materials. 5.36 Mt (similar to 78.6%) of the extracted materials belong to aggregate production and they represent similar to 19.5% of the ECO(2)eq. Portland cement is the largest contributor to ECO(2)eq and the constituent material with the lowest ME. Using recycled aggregates is the strategy that contributes the most to the reduction of the use of raw materials (similar to 8.9% lower use of raw material by using 20% recycled coarse aggregate), while replacing Portland cement with supplementary cementitious materials (SCM) is the one that reduce the most the ECO(2)eq (the use of Portland cement without SCM would increase ECO(2)eq by similar to 13.6%). This research provides a novel approach that quantifies the effect of modifying the concrete mix and replacing raw materials by secondary raw materials, bringing a new understanding to the sustainability of building materials.