Concrete Mix Design of Recycled Concrete Aggregate (RCA): Analysis of Review Papers, Characteristics, Research Trends, and Underexplored Topics

Recycled concrete aggregate (RCA) has been widely adopted in construction and emerged as a sustainable alternative to conventional natural aggregates in the construction industry. However, the study of holistic perspectives in recent literature is lacking. This review paper aims to provide a comprehensive analysis of RCA, highlighting its properties, applications, and overall sustainability benefits to facilitate the comprehensive points of view of technology, ecology, and economics. This paper explores the manufacturing process of RCA, examines its mechanical and durability characteristics, and investigates its environmental impacts. Furthermore, it delves into the various applications of RCA, such as road construction materials, pavement bases, and concrete materials, considering their life cycle performance and economic considerations. This review reveals that there is a need for systemic data collection that could enable automated concrete mix design. The findings concerning various mix concrete designs suggest that increasing the 1% replacement level reduces the compressive strength by 0.1913% for coarse RCA and 0.2418% for fine RCA. The current critical research gaps are the durability of RCA concrete, feasibility analyses, and the implementation of treatment methods for RCA improvement. An effective life cycle assessment tool and digitalization technologies can be applied to enhance the circular economy, aligning with the United Nations’ sustainable development goals (UN-SDGs). The equivalent mortar volume method used to calculate the RCA concrete mix design, which can contain chemical additives, metakaolin, and fibers, needs further assessment.