Suitability of Recycled Aggregate as a Replacement for Natural Aggregate in Construction

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Title: Suitability of Recycled Aggregate as a Replacement for Natural Aggregate in Construction

Author(s): Deb Dulal Tripura, Shubham Raj, Sher Mohammad, and Rima Das

Publication: Special Publication

Volume: 326

Issue:

Appears on pages(s): 37.1-37.10

Keywords: recycled concrete aggregate; interfacial transition zone; unconfined compressive strength; splitting tensile strength; modulus of rigidity, bond strength

Date: 8/10/2018

Abstract:
This study investigates the effect of recycled coarse aggregate (RCA) as replacement of natural coarse aggregate on the strength properties of concrete. The investigation was carried out by conducting unconfined compressive strength (UCS) test, indirect tensile strength (ITS) test, flexural strength test and bond strength test on five concrete mixtures using 0%, 25%, 50%, 75% and 100% by weight of RCA as replacement of natural coarse aggregate. The test samples were prepared with a target strength of 40 MPa (6000 psi). Water-cement ratio (w/c) and slump was adopted as 0.40 and 100 mm (4.0 in.) respectively. It was observed that as the percentage of RCA in concrete mixtures increased, the strength properties of concrete decreased. There was a decrease of 1.92%, 5.43%, 10.46% and 27.13% in UCS for RCA 25%, 50%, 75% and 100% respectively. Tensile strength of concrete decreased considerably on addition of RCA. All samples achieved target strength except 100% replacement. Also, as the percentage of RCA increased in concrete mixtures, the rate of strength gain over time decreased. However, RCA can be efficiently used as a replacement of natural coarse aggregate up to 25% without any major laboratory testing and up to 50% with proper testing and care for concreting where high strength is not a priority.