In this paper, the effect of accelerated curing on the strength properties of concrete produced by replacing natural coarse aggregates with recycled aggregates is presented, thereby establishing a correlation for flexural strength between accelerated-curing and 28-day normal curing of concrete made with recycled coarse aggregate. The investigation is performed on concrete of grade M20. The different percentage replacement of natural coarse aggregates with recycled aggregates considered are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%. A reliable correlation between accelerated curing and 28-day curing for flexural strength in the form of linear equation serves as an invaluable decision-making tool for any quality assurance program for concrete produced with recycled aggregate.

Recycling of concrete waste is necessary from the viewpoint of environmental preservation and effective utilization of natural resources. The utilization of recycled aggregates from processing construction and demolition waste in new construction has become more important over the last two decades. There are many factors contributing to this, from the non-availability of new material and the damage caused by the quarrying of natural aggregate and the increased disposal costs of waste materials. Given this background, it is essential to develop new information on the use of demolished concrete in structural applications and broaden its use in concrete industry (Shayan and Xu, 2003).

Numerous research and development projects on the reuse and recycling of demolished concrete and addition of by-products to concrete have been conducted. However, successful cases are limited to some exceptional materials. The reasons as to why it is difficult to extend the sustainable use of concrete materials are: lack of suitable laws, lack of codes, specifications standards and guidelines, cost, poor image, lack of experience, low quality, variations in quality, too many kinds and too large amounts of by-products, inefficient supply system and lack of proper information (Rao et al., 2006).

Structural Engineering Journal, Recycled coarse aggregate, Accelerated curing, Correlation