Engineering and microstructural properties of self-compacting concrete containing coarse recycled concrete aggregate

In this paper, the possibility of utilizing coarse recycled concrete (CRCA) aggregate obtained from a Construction and Demolition Waste (CDW) Plant in Delhi for making a 60 MPa Self compacted concrete (SCC) was evaluated. The CRCA was used in as-collected condition and was not processed any further. Aggregate Packing (bulk) Density (APD) method was adopted to obtain an aggregate mixture exhibiting maximum bulk density/least void content (45%) with which the SCC-CRCA mixture was prepared. In addition, SCC was also made using aggregate mixtures in which the NCA was replaced with CRCA at 0%, 20%, and 100 % (of the total coarse aggregate content) by weight. The cement, fly ash, silica fume, and water were kept constant for all SCC mixtures. The effect of CRCA on the flow behavior, mechanical strength, shrinkage characteristics, and microstructure properties of SCC mixtures were evaluated. The test results indicated that the SCC mixtures made with CRCA up to 45% replacement can be used for structural concrete which is higher than that recommended in Indian (20 %) and International specifications (35 %) for traditionally vibrated (conventional) concrete.