Reuse of Fine Concrete Demolition Wastes as a Supplementary Cementitious Material in Concrete

Abstract

Materials from demolition are only recycled if they are economically competitive on the one hand and technically acceptable on the other, meaning they can be implemented without risking disruption to the performance of the construction material. Among these materials are demolished concretes. This type of material (waste) is currently reused as recycled aggregate, commonly referred to as gravel. Indeed, the latter contains grains of anhydrous clinker, which may play a significant role in determining the properties of concrete. In the context of waste valorization, this study focuses solely on the influence of incorporating finely crushed concrete demolition waste (CDW) as an active additive or as a supplementary cementitious material in the cement matrix used to make concrete. The results showed that the addition of up to 10% of concrete demolition waste significantly improved physical properties such as the air void content and workability of fresh concrete. Furthermore, the compactness of hardened concrete also improved based on adding 10% of CDW as a result of increasing the speed of sound. Therefore, the compressive strength of concrete was also improved by 20% when 10% waste was added compared to the control concrete. This indicates that concrete demolition waste (finely crushed) can replace cement and therefore contribute to reducing binder consumption.