Supplementary data for "Reduction of the environmental impacts of reinforced concrete columns by increasing the compressive strength - A life cycle approach"

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 the demand for the materials tends 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 were also a significant reductions 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.

建筑行业是对全球环境影响最为显著的行业之一。水泥是全球第二大用量的材料，混凝土的年消耗量介于20至30吉吨之间。未来100年间，此类材料的需求预计将持续攀升。提升混凝土强度以降低材料消耗，是现有文献中提出的缓解建筑行业环境影响的策略之一。然而，针对该策略在建筑生产中的实际效益的研究相对有限。本文以一栋15层钢筋混凝土建筑为研究对象，针对其柱构件采用三种不同强度等级的混凝土（30MPa、40MPa和50MPa）进行设计。基于柱构件的混凝土体积及钢筋用量数据，开展从摇篮到大门的生命周期评估（Life Cycle Assessment, LCA），旨在筛选出生产阶段环境影响最低的方案。研究结果显示，柱构件采用高强度混凝土可有效降低环境影响并减少材料消耗。混凝土强度提升的直接效应使混凝土消耗量降低15%；同时，其间接效应亦带来显著改善，钢筋消耗量降幅可达22%。综合更高抗压强度的直接与间接效应，钢筋混凝土在生命周期评估涵盖的所有类别中，其环境影响均实现了降低。