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Abstract-
Reusing waste materials as an alternative to natural aggregates can help in reducing environmental problems, pollution, waste disposal and global warming. From the last few years, it has been found that the waste generated from demolition of construction site and old structures is increasing at more rapidly. Thus, reusing and recycling these wastes may reduce the usage of natural aggregates and thus contribute in reducing environmental hazards. . The latest trend in construction industry is to use alternate materials which can be best substitute of natural aggregates so that there is no compromise in terms of strength and durability considerations of structure. As one of the most commonly used building materials in the world, concrete, composed of aggregate, sand, cement and water, can be recycled and reused in a variety of applications. Using crushed concrete as fill and subgrade material under roads, sidewalks and foundations has been the most common of these applications. However, research has been ongoing over the past 50 years in many countries including Germany, India, Canada, Japan, the United States, China, and Australia investigating the use of crushed concrete from demolished old concrete structures to fully or partially replace the virgin
aggregate used to produce new concrete for use in building and pavement applications. Producing concrete using recycled concrete aggregates (RCA) has several advantages, namely, the burden placed on non-renewable aggregate resources may be significantly decreased, the service life and capacity of landfill and waste management facilities can be extended, and the carbon dioxide emissions and traffic congestion associated with the transport of virgin aggregates from remote sites can be reduced. Sustainable resource management and development have been at the forefront of important issues concernin the construction industry for the past several years. Specifically, the use of sustainable building materials and the reuse and recycling of previously used building materials is= gaining acceptance and becoming common place in many areas. This research investigates the interrelationships between aggregate properties, concrete properties and the bond properties between reinforcing steel and RCA concrete. Forty pullout tests were carried out in order to investigate the bond behaviour between recycled coarse aggregate concrete and steel bars. Four recycled coarse aggregate (RCA) replacement percentages (i.e., 0%, 50% and 100%) with water-cement ratio 0.43, 0.44, are considered in this paper. Based on the test results, the influences of both recycled coarse aggregate replacement percentages and water- cement ratio on the bond strength between the recycled coarse aggregate concrete and steel rebars were investigate.