Bond characteristics of concrete made of recycled aggregates from building demolition waste

Abstract

This paper presents the experimental results of pull-out tests conducted to determine the bond characteristics of concrete using aggregates made from the recycling of concrete waste from demolished buildings. Factors such as water–cement ratio (0·5, 0·4 and 0·3), bar diameter (ø = 10, 12 and 16 mm), embedment length (2·5ø, 5ø and full depth of specimen) are considered. The pull-out test is performed on concrete produced from both natural aggregate and recycled concrete aggregate, and an assessment of the subsequent performance is made. Mechanical properties such as compressive strength, split tensile strength and modulus of rupture are also reported. The bond stress and slip at failure are determined by experimentation and a comparison is made. The recycled aggregate concrete performed better than the natural aggregate concrete in terms of normalised bond stress. Lowering the water–binder ratio has the effect of increasing the bond stress and slip values. With the increase in bar diameter and embedment length, a decrease in bond stress and increase in slip can be observed. An equation to determine the bond stress is proposed based on the experimental results obtained. A comparison is made with various models proposed in the literature.