Utilizing recycled aggregate concrete in sustainable construction for a required compressive strength ratio

Selecting efficient and economical methods to recycle the original concrete in construction and demolition wastes is regarded as one of the obstacles for construction companies to successfully achieve sustainable development. This study explored this challenging task by examining the influences of the compressive strength ratio between original concrete and recycled aggregate concrete on the slump, compressive strength, and carbonation resistance of recycled aggregate concrete. The microstructures of new and old mortars in the recycled aggregate concrete before and after carbonation were further investigated. A new sustainable construction design reflecting the compressive strength ratio effect was proposed. Results revealed that adjusting the compressive strength ratio can furnish different slump, compressive strength, and carbonation depth values, while also reducing mortar inhomogeneities. Specifically, increasing the compressive strength ratio could improve these properties, which are in agreement with the results using some time-consuming and uneconomical strengthening techniques in the published literature. Therefore, construction companies can use more original concrete by adjusting the compressive strength ratio according to the requirements of different structures. Additionally, the construction waste treatment organizations should classify the waste concretes from different sites rather than mixing them and then directly utilizing them in actual projects. (C) 2020 Elsevier Ltd. All rights reserved.