A Comparative Midpoint-Based Environmental Impact Assessment of Conventional and Eco-Friendly Controlled Low-Strength Materials for Utility Trench Applications

The rapid industrialization and urbanization of recent decades have posed severe challenges to the natural environment, resulting in a significant increase in waste production. Ready-mixed concrete (RMC) manufacturers face the dual challenges of managing returned concrete and the disposal of waste generated during the washing process. The volume of returned fresh concrete presents environmental and economic challenges, requiring sustainable solutions for resource recovery and waste minimization. Given the need for sustainable development, an increasing number of recycled waste materials and industrial by-products are being utilized to develop sustainable, eco-friendly, controlled low-strength materials (CLSM). Nonetheless, the environmental benefits and impact of this type of material are still insufficiently quantified. This research study employed a Life Cycle Assessment (LCA) to compare the environmental impacts of conventional and eco-friendly CLSM alternatives. A comparative LCA was performed using the ReCiPe 2016 Midpoint (H) life cycle impact assessment method in the OpenLCA software. The results indicated that eco-friendly CLSM, which incorporates returned concrete waste and industrial by-products, is the more sustainable option across all six impact categories when compared to conventional CLSM. Therefore, this study will be helpful for RMC and contractors in facilitating their decision-making process for selecting a more sustainable CLSM.