4 - The use of construction and demolition waste as a recycled aggregate in sustainable concrete production: workability, strength and durability properties

Abstract

Aggregate is one of the most used construction material for infrastructural construction. Recently, depletion in aggregate is now encountered by construction workers globally. This depletion calls for a need to reuse and develop aggregates in an innovative and ecofriendly manner. This is in a bid to improve on the abundance of aggregates and to also improve the life cycle of infrastructures. This chapter will assess recycled and artificial aggregate, innovative ecofriendly binders and life cycle assessment in the construction industry and in the built environment. This was achieved by focusing on artificial and recycled aggregates' material composition. Additionally, a comparative assessment of the physicomechanical properties of recycled aggregate was espoused. The result revealed that the water absorption and crushing index of recycled aggregate concrete are higher than the normal aggregate concrete. This invariably affects the mechanical properties of recycled concrete aggregate (RCA). The major reason for the reduced mechanical properties of recycled aggregate concrete is the increase in the water-cement ratio in order to make the concrete mix workable due to the roughness of the aggregate and the elongated shape of the aggregate. Consequently, this has an adverse effect on the concrete's structural strength compared with the natural aggregate concrete. The review also revealed that the carbonation treatment method was the most effective for recycled aggregate. However, the presaturation method of treatment improved the frost resistance of recycled aggregate. Using the polymer emulsion treatment method enhanced the workability and the durability of concrete. Additionally, in frost-prone regions the use of fly ash and metakaolin improved the frost resistance of recycled aggregate in concrete production. The outcome of the review will guide construction workers, engineers, researchers, and material specialists on the treatment methods of recycled aggregates and the workability, strength, and durability properties of recycled aggregate concrete for the construction of ecofriendly infrastructure now and in the foreseeable future.