Title: Waste Concrete as Aggregate for New Concrete

Author(s): S. Frondistou-Yannas

Publication: Journal Proceedings

Volume: 74

Issue: 8

Appears on pages(s): 373-376

Keywords: aggregates; coarse aggregates; composite materials;compressive strength; concretes;consistency tests;crushed concrete;demolition; gravel; mechanical properties;modulus of elasticity; mortar bond strength; waste disposal;waste treatment; wastes.

DOI: 10.14359/11019

Date: 8/1/1977

Abstract:
The mechanical properties of conventional concrete and of concrete containing pieces of concrete from demolition waste in the place of conventional coarse aggregate were evaluated and compared. The results suggest that recycled concrete best matches the mechanical behavior of conventional concrete when the former contains recycled aggregates enriched in gravel at the expense of mortar, The water-cement ratio does not appear to significantly affect the relative merits of the recycled product and its control. The strength of the aggregate-matrix mortar bond is reduced to about 55 to 88 percent of the strength of the control when conventional coarse aggregates are replaced with pieces of old concrete. Furthermore, recycled aggregate concrete is equally workable as the control, and has a compressive strength of at least 76 percent and a modulus of elasticity from 60 to 100 percent of the control. It is suggested that recycled concrete is a possible substitute for aggregate in areas where concrete disposal is a problem or in areas where natural aggregates are not accessible.