Studies on mechanical performance of treated and non-treated coarse recycled concrete aggregate and its performance in concrete-an Indian case study

Abstract

In India, utilization of construction & demolition (C&D) waste-based coarse recycled concrete aggregate (CRCA) for RCC work is limited up to 20% for M25 grade of concrete as codified in IS 383:2016. However, enhanced utilization is not possible until classification based on quality grading of C&D waste-based aggregate is made available. One of the possible ways to classify C&D waste-based aggregate can be routed based on specific gravity and water absorption value of the parent rock which is generally affected by the adhered mortar. In the present study, C&D waste-based coarse recycled concrete aggregate (CRCA) sourced from two different sources was studied holistically. CRCA aggregates were subjected to mechanical treatment in a Los Angeles machine and Characteristics of CRCA before and after treatment were evaluated and compared. Further, a comparative study in fresh, hardened, and durability stages was conducted on the properties of concrete made with treated and non–treated CRCA. Fresh, hardened, and durability properties of concrete made with C&DW-based CRCA investigated for the (a) Fresh properties – workability in terms of slump, and air content. (b) Hardened properties–compressive and flexural strength, modulus of elasticity, drying shrinkage (c) Durability properties –resistance to chloride (RCPT, as per ASTM C1202), resistance to carbonation as per ISO 1920 Part 12 and resistance to water penetration as per IS 516 Part2 / Section-1. From the study, it can be concluded that physical properties such as specific gravity and water absorption of CRCA can be used as a tool for the grading of C&D waste-based CRCA. Based upon fresh, hardened, and durable behavior of concrete made with CRCA, it was observed that non-treated CRCA can be used up to 40 % for a grade of concrete up to M 30 whereas treated CRCA can be used up to 100 %. This was attributed to the improvement in the ITZ.