The use of recycled concrete aggregates has the potential to create large economic and environmental benefits for the construction industry. Use of recycled concrete aggregate not only reduces the need for dumping of demolition waste in landfill but also reduces the need for new natural aggregates. However, the effects of including recycled concrete aggregates in new concrete mixes, is an area that is currently not particularly well studied or understood.
This thesis contains two parts. Firstly it presents a review of the available literature on the topic. It then contains an experimental study designed to investigate the effects of the inclusion of various proportions of recycled concrete aggregates on the mechanical properties of concrete.
A review of the available literature reveals that concrete containing recycled concrete aggregate has lower compressive strength, lower tensile strength, lower elastic modulus and lower density than equivalent natural aggregate concrete. Recycled aggregate concrete also exhibits higher drying shrinkage and higher creep than natural aggregate concrete.
The experimental study indicates that as the proportion of recycled concrete aggregate included in the mix is increased, the compressive strength, flexural tensile strength, modulus of elasticity and density are all reduced. It also shows that the addition of recycled concrete aggregate causes an increase in drying shrinkage. It appears, however, that the addition of small proportions of coarse recycled concrete aggregate (20%) causes no significant change in the properties of the concrete.