CONCRETop method: Optimization of concrete with various incorporation ratios of fly ash and recycled aggregates in terms of quality performance and life-cycle cost and environmental impacts

This study shows how to optimize traditional and non-traditional concrete mixes from various perspectives, specifically technical performance (e.g. mechanical and durability characteristics), and economic (cost) and environmental (e.g. global warming and energy consumption) life cycle. Firstly, the weight to be considered for each of these perspectives (dimensions) of performance depends on the concrete application and on the user's requirements. In this study, concrete mixes containing various amounts of recycled concrete aggregates (RCA) and/or fly ash (FA) are optimized for different applications in the construction sector, namely high-rise building, sustainable residential housing, economical residential housing and residential housing close or far from the sea. For that purpose, the CONCRETop (a multi-criteria decision method for concrete optimization) methodology (developed by the authors of this study) was applied to these concrete mixes by considering the global requirement scenarios (e.g. cost, strength, green, service life and business as usual) that are normally demanded by users. This study is an example of CONCRETop's application and also contributes to its validation. The results show that, for all applications and scenarios that users may demand, the optimum concrete mixes in terms of concrete characteristics, cost and environmental impact are the ones produced with both FA and RCA incorporation, rather than their individual incorporation. This study shows that CONCRETop is straightforward in its application, i.e. it does not require excessive time and resources, and is focused on the final output, where the selection of the optimal concrete mixes can be directly used by the user, avoiding therefore lengthy inventory analysis and modifications.