Recycled concrete as an aggregate in the concrete mix

Concrete has been the most common construction materials for many decades. Recently, sustainability associated with concrete use has become an important concern within construction industry and more pressure is being placed to change/modify current construction practices and reduce the waste that is generated to develop a more sustainable environment. Waste product recycling has been continually gaining support over the past few decades and research and investigations into the feasibility of utilizing particular waste products for recycling have been continually increasing. A number of studies have been reported on the use of recycled concrete in concrete mix in recent years. However, these studies mainly concentrated on the recycled concrete with known properties such as initial strength (before being used as recycled concrete). This paper presents the preliminary results of a project at Central Queensland University, which aims to understand the effect of recycled concrete on the properties of concrete in order to develop the applications of recycled concrete. For this purpose, recycled concrete with unknown initial properties, which was obtained from a local recycle yard, was used in the concrete mixes. Varying amount of recycled concrete was used to replace the aggregate and, initially, the samples were tested for its strengths. In addition the material properties of recycled concrete are also tested for the use as aggregate in concrete mix. The experimental results will be analyzed and discussed in terms of concrete strength, the properties of recycled concrete used and amount of recycled concrete used in the concrete mix.