Effect of Coarse Recycled Concrete Aggregate on the Microstructural and Durability Properties of Self Compacting Concrete

Abstract

This paper presents the influence of different amounts of Coarse recycled concrete aggregate (CRCA) obtained from a Construction and Demolition Waste (CDW) Plant in Delhi, on the durability properties of a 40 MPa Self Compacting Concrete (SCC). 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 mixes was prepared. In addition, SCC was also made using aggregate mixtures in which the Natural coarse aggregate (NCA) was replaced with CRCA at 0% and 100 % (of the total coarse aggregate content). It has also been observed with the Mercury intrusion porosimetry (MIP) and Scanning electron microscopy (SEM) analysis that the incorporation of fly ash in SCC mixtures containing different contents of CRCA, resulted in the production of SCC-CRCA mixtures, with higher/comparable performance to that of control SCC mixture. The test results indicated that the SCC mixtures SCC mixtures exhibited very low chloride ion permeability at 28 days, lower carbonation depth. SCC made with CRCA up to 45% replacement can be used for structural concrete which is higher than that recommended in Indian specification (20 %) for normal concrete.

Keywords

• self compacting concrete, natural coarse aggregate, coarse recycled concrete aggregate, aggregate packing density, durability