Life cycle assessment of sustainable concrete with recycled aggregate and supplementary cementitious materials

Massive emissions and energy consumption during concrete production, together with the demand for concrete, continuously threaten sustainable development and human health. To offset the negative impacts of concrete while maintaining the engineering properties, raw material alternations such as using recycled aggregate (RA) and supplementary cementitious materials (SCMs) are promising and frequently studied. Although these studies recognize such concrete products as strong, cost-saving, and environmental-friendly, only limited research has been integrated the technical properties of sustainable concrete to measure the environmental impacts by life cycle assessment (LCA). In this research, 570 experimental mix designs of concrete exclusively incorporating RA and SCMs are extracted from multiple scientific studies, to conduct a comprehensive analysis of their environmental behaviour. During the process, the multifunctional allocation issues in SCMs and the increase of alternative fuel utilization to the impact of sustainable concrete are explored. The results are also used to develop a multilayer perceptron (MLP) model to predict the carbon emission and energy consumption of sustainable concrete. It is found that the environmental impact of sustainable concrete are generally related to the compressive strength, effective water-to-binder ratio, and RA and SCMs incorporation ratios, and the proposed MLP model using these variables can make predictions. Allocation coefficient determined has a significant effect on the impact of sustainable concrete, especially when the silica fume is applied. In addition, promoting higher portion of alternative fuel utilization, leading to a cleaner production of cement, could be an opportunity to greatly reduce carbon emissions and energy consumption of sustainable concrete.

Automated summary

Massive emissions and energy consumption in concrete production pose threats to sustainable development and human health. Studies on sustainable concrete mainly focus on technical properties, while limited research has integrated life cycle assessment (LCA) to measure environmental impacts. This research examines 570 concrete mix designs incorporating recycled aggregate (RA) and supplementary cementitious materials (SCMs) to analyze their environmental behavior and develop a model to predict carbon emissions and energy consumption. The results show that the environmental impact of sustainable concrete is related to compressive strength, water-to-binder ratio, and RA/SCMs ratios, and the allocation coefficient and alternative fuel utilization significantly affect the impact.