Investigating the impact of crumb rubber aggregates on the fresh and physical characteristics of self-compacted concrete: a comprehensive review

Incorporating the substantial waste generated by the disposal of end-of-life tires into the manufacturing process of self-compacted concrete (SCC) presents a viable and environmentally responsible approach to address significant environmental concerns. An extensive study has been conducted to enhance the technical benefits and viability of using scrap vehicle tires as a substitute for traditional aggregates in concrete, particularly the performance of self-compacting concrete containing crumb rubber from waste tires. This study provides a comprehensive review and evaluation of the data derived from over 43 distinct studies on using crumb rubber (CR) as sand replacement in SCC to emphasize and verify the fundamental characteristics of such concrete. The primary objective of this review paper is to provide an in-depth evaluation of the impact of CR on the performance of SCC in its fresh and physical state. Moreover, in this study, fresh properties, including slump flow diameter, T500, V-funnel flow time, L-box height ratio, J-ring flow diameter, TJ500, J-ring high, sieve segregation, air content, and U-box test, and physical properties including porosity, water absorption, and fresh and dry density have been conducted. It has been found that the addition of CR has a detrimental effect on SCC's physical and fresh characteristics, apart from resistance to segregation. The predicted decrease/increase in the fresh and physical characteristics of the SCC, including CR, was given based on the findings of the studied papers. Furthermore, empirical models that illustrated the relationships between various fresh attributes were established using the findings of the examined research. Moreover, recommendations for future work and directions for this field of research have been detailed.