Engineering products’ sustainability has changed from being a choice to a crucial requirement. In this study, the impact of employing 20 % fly ash (FA) and/or 12 % silica fume (SF) as cement substitutes in the production of recycled aggregate concrete is examined. The examination was conducted in two stages, evaluation stage and analysis stage. In the evaluation stage, the mechanical characteristics, environmental impact, and production costs of ten concrete mixtures were assessed with laboratory experiments and data collection. While in the analysis stage, three multi-criteria decision-making techniques (namely: EDAS, VIKOR, and TOPSIS) were utilized to optimize the most valuable and sustainable concrete mixture. The key results displayed that utilizing up to 70 % of recycled concrete aggregate with an optimal dosage of a combination of 20 % FA and 12 % SF provides high-quality, environmentally friendly, and costly effective concrete.

In this study, a wide-ranging life cycle assessment and multi-criteria analysis for close-loop cycling of concrete are conducted. Considering six performance keys in the technical (compressive strength at short and long ages), environmental (human health, ecosystem quality, climate change, resources), and economic (costs), a solid framework is created and analyzed by three multi-criteria decision-making techniques, namely, TOPSIS, VIKOR, and EDAS. The weight that must be taken into account for each of the applied criteria depends on the specific application and the demands of the user. Nevertheless, two different weighted methods, namely, the equal performance method and the entropy method, have been employed in this work to optimize for various construction-related applications, specifically sustainable residential buildings and residential housing. The findings demonstrate that the concrete mixtures produced with 20% FA+12% SF and MRCA incorporation are the best in terms of the criteria used for all applied techniques and the two weighted methods. This study demonstrates that multi-criteria decision-making techniques are simple to apply, requiring minimal time and effort and focusing on the finished result, allowing users to choose the best concrete mixtures. The proposed framework recommends the closed-loop recycling of concrete by introducing supplementary cementitious materials for sustainable, economical, and performance-based design applications.

Through experiments with two generations of recycled aggregate concrete and the application of Multi-Criteria Decision-Making techniques, this research aims to establish a sustainable framework of second generation recycled aggregate concrete selection. The technical and environmental performances of seven concrete mixtures were evaluated experimentally and analytically. In addition to the control mixture, six mixtures were produced with two proportions of recycled concrete aggregate or multi-recycled concrete aggregate (30 % and 70 %). Four Multi-Criteria Decision-Making techniques, namely TOPSIS, EDAS, WSM, and WPM, were applied for optimizing the best concrete mixture in terms of technical and environmental based. The results of the four techniques agreed that reusing recycled aggregate concrete is possible as high quality and environmentally friendly concrete. Yet the highest CO2 emissions have belonged to the control mixture where no recycled or multi-recycled aggregate concrete was used.