Restrained Shrinkage Cracking of Recycled Aggregate Concrete

Abstract

The increase in drying shrinkage and decrease in tensile properties of concrete proportioned with recycled concrete aggregate (RCA) can result in a high risk of cracking under restrained conditions. However, the reduction of the modulus of elasticity of such concrete, can lead to greater stress relaxation and reduction in cracking potential. An experimental program was undertaken to evaluate the effect of using RCA at high substitution rates of 50 and 100% (by vol.) on the cracking potential under restrained conditions. Four different types of coarse RCA, two binder types, and water-to-cementitious materials ratio (w/cm) of 0.37 and 0.40 were considered in the study. Mechanical properties, drying shrinkage, and cracking potential using the ring test were investigated. Test results indicated no cracking up to 35 days in the case of the reference mixture and the concrete prepared with 50% RCA replacement. The 28-day stress rate of such mixtures were limited to 0.12 MPa/day. Depending on the RCA type, the incorporation of 100% coarse RCA in a binary system made with 0.40 w/cm increased the 35-day cracking potential to up to 74%, with values of stress rate ranging from 0.25 to 0.34 MPa/day. The mixtures proportioned with 100% RCA developed tensile creep coefficient of 0.34–0.78 at the time of cracking compared to 0.34–0.36 for the reference concrete at the same age. However, greater elastic concrete strain and lower tensile strength resulted in reduced time to cracking at 100% RCA replacement, which was 9.0–11.0 days.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Bins; Concrete aggregates; Concretes; Cracks; Mixtures; Recycling; Shrinkage; Stress relaxation; Tensile strength; Cracking potential; Properties of concretes; Recycled aggregate concrete; Recycled concrete aggregates; Restrained conditions; Rigid pavements; Sustainable infrastructure; Water-to-cementitious materials ratio; Concrete mixtures; Restrained cracking

International Standard Serial Number (ISSN)

1359-5997; 1871-6873

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2017 Springer Verlag, All rights reserved.

Publication Date

01 Aug 2017

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