A comprehensive review towards sustainable approaches on the processing and treatment of construction and demolition waste

A massive boom in global construction has led to an enormous generation of construction and demolition (C&D) waste. C&D waste is the largest stream of waste, which needs to be treated and utilized efficiently for achieving sustainable goals. Multiple economical and valuable materials are embedded in C&D waste, most of these can be reused as construction materials. Ideally, these wastes are processed or treated near the demolition sites to ensure a constant supply of raw materials such as recycled aggregates for its use in the construction of roads, buildings, and urban landscapes. Several challenges are posed in the processing and treatment of C&D waste as a result of variable material properties as well as its bulky nature. From this point of view, this article presents a structured, comprehensive review of the existing literature on various tools and techniques for procuring recycled aggregates (RA) from C&D leftovers. The latest processing technologies, and subsequent treatment processes for recycled aggregates to make it suitable for further use in concrete is discussed and critically analyzed. Also, diverse approaches for treating the RA are evaluated critically with prime focus on removal of adhered mortar fractions and surface coating techniques. In addition, the modified mixing approach and its implementation in mix design for RA based concrete is emphasized. This article also covers the studies on recycled aggregate concrete at microstructural level, which include characterization techniques such as SEM-EDAX, XRD, FTIR and TGA. Emphasis is also given to embrace the deficiencies associated with RA concrete and improvement techniques for its inclusion in construction works.

On the basis of the extensive review, it is understood that subjected to processing of the C&D debris, it yields useful recycled aggregates that can be incorporated into concrete up to an optimum percentage between 15 and 20%. Further, there is a requirement for specified pre-treatment methods that enhances the physio-chemical properties. Also, there is a necessity for the assimilation of mineral admixtures of micron, sub-micron to nano size for overcoming the shortcomings of recycled aggregates for the production of sustainable and high-performance concrete.