Concurrent paste replacement and aggregate replacement strategy for producing eco-efficient and low-carbon concrete

Abstract

To reduce the consumptions of cement and natural aggregate, and thereby achieve better eco-efficiency in concrete production, the strategy of adding a powder waste as a filler to substitute part of cement paste without changing paste composition and substitute part of aggregate for widening particle size range of aggregate is proposed. Such addition of a powder waste as both paste and aggregate replacement reutilises the waste to reduce waste disposal, reduces the cement content to lower carbon footprint, and reduces the aggregate content to minimise dredging and quarrying. Herein, the feasibility of such concurrent paste and aggregate replacement strategy was studied by using granite polishing waste (GPW) as the filler to be added. A series of 25 concrete mixes with GPW added as paste and/or aggregate replacement were tested. It was found that the concurrent paste and aggregate replacement strategy would not just reduce the cement and aggregate contents, but also significantly improve the workability, strength and strength/cement ratio of the concrete produced. Hence, it is a good strategy for the production of high-performance, eco-efficient and low-carbon concrete.