Investigation the effect of Different Types of Recycled Concrete Aggregates on the Engineering Properties of Concrete

In recent decades, concurrent with expansion of cities, the demand for new buildings and structures has increased. On the other hand, aggregates constitute the biggest portion of concrete. As such, providing natural aggregates for producing concrete has become a challenge due to shortage of resources. Also, treatment of construction waste materials resulted from demolition of old structures has been another concern. One way to handle these problems is reusing concrete waste as a new material in new construction. Nowadays, recycled concrete aggregate (RCA) is used in concrete as a partial or complete replacement for natural aggregate (NA). Performance of recycled aggregate concrete (RAC) is influenced by the characteristics of the parent concrete from which RCA is obtained. In this research, the mechanical properties and the durability of three types of RCAs from different sources were evaluated. For this purpose, the aggregates' Los Angeles abrasion value and freeze/thaw soundness value were determined. Moreover, eight concrete mixes incorporating different amounts of the RCAs as coarse aggregate were cast and their water absorption coefficient, compressive strength and deicer-salt scaling resistance were assessed. The results showed that the mechanical properties of RCAs had a direct relationship with the mechanical properties and durability of RACs. Also, the type of RCAs had no significant impact on the performance of RACs. However, increasing the replacement amount of RCA decreased the strength and deicer-salt scaling resistance of RACs.