Reduction of the environmental impacts of reinforced concrete columns by increasing the compressive strength: a life cycle approach

Redução dos impactos ambientais de pilares de concreto armado ao aumentar a resistência à compressão: uma abordagem de ciclo de vida

Abstract

The building industry is one of the greatest environmental impact causers in the planet. Cement is the second most used material in the world and the consumption of concrete ranges between 20 to 30 Gt yearly. This demand for the materials ten ds to increase for the next 100 years. The increase of concrete strength to reduce the material consumption is one of the options proposed in literature to reduce the environmental impacts in building industry. However, few studies have been carried about the actual advantages of this strategy in building production. In this paper, a 15-storey reinforced concrete building was designed with three different concrete grades for its columns: 30 MPa, 40 MPa and 50 MPa. The results for the volume of concrete and the amount of reinforcing steel to produce the columns were used to perform a cradle-to-gate life cycle assessment (LCA) to determine the alternative with less environmental impacts in the production stage. Results indicate an advantage to adopt higher strength concretes in columns to reduce environmental impacts and the consumption of materials. Direct effects of higher strength in concretes made possible to reduce the consumption of concrete by 15%. There was also a significant reduction caused by indirect effects of higher strengths in concrete, with the reducing of steel consumption up to 22%. With the combination of the direct and indirect effects of higher compressive strengths, it was possible to reduce the environmental impacts of reinforced concrete in all categories studied in the LCA.

Keywords:
reinforced concrete; life cycle assessment; sustainability; concrete columns