The The eco-efficiency indicators of concretes containing mineral admixtures

Abstract

Portland cement production is responsible for around 8% of CO₂ emissions in the world, which requires measures to reduce the consumption of this material in new buildings. The use of mineral admixtures has been an alternative for reducing the cement consumption in concretes. In several studies, reductions in the mechanical strength of concretes have been reported with the reduction of cement consumption. Besides, the analysis of the eco-efficiency of concretes with additions has been little explored. This article compares the eco-efficiency of concretes produced with different mineral additions, using the indicators CO₂ intensity (CI) and binder intensity (BI). A total of 332 concrete formulations prepared in several studies available in the literature were evaluated. The determination of CI and BI was made in concretes without addition and in concretes that had the following mineral admixtures in their composition: silica fume, metakaolin, rice husk ash, fly ash, or limestone filler. The BI of the concretes produced in the consulted studies varied between 3,52 and 18,59 (kg/m³)/MPa, while the CI varied between 3,34 to 18,12 (kgCO₂/m³)/MPa, which shows that both high and low eco-efficiency concretes have been developed. The silica fume, rice husk ash and fly ash proved to be the most effective additions to reduce the CI and BI of concretes. The concretes produced with CP II E-32 and CP II F-40 had greater potential for BI reducing, while the concretes produced with CP IV-32 and CP II E-32 were the CI lowest average.