Sustainable structural material combining recycled aggegate and steel fibres

Recyclable concrete is now increasingly recognised as a sustainable building material, which could be effectively used in building construction. However, at present, recycled concrete created from recycled aggregate has mainly been used for non-structural and sub-grade applications around the world because companies have long believed that it is inferior to the normal aggregate generation. This research was undertaken with the hypothesis that recycled concrete can be as strong as the normal concrete which is suitable for structural applications when incorporated with steel fibres. Previous research has shown that steel fibre can effectively improve the toughness, shrinkage, and durability characteristics of concrete. Recycled concrete, which is weak in shrinkage properties, can therefore be enhanced by incorporating steel fibres. This paper reports initial experimental results that aims to explore the behaviour of recycled concrete when steel fibre is added. The experiments considered varying steel fibre volumes of about 0%, 30% and 60% with recycled aggregate replacement ratios of about 0%, 30% and 100%. It is found that the more recycled aggregate replacement ratio of the recycled concrete, the lower the compressive strength is. However, the addition of steel fibre can improve the compressive strength of the concrete mixes. The initial experiments reveal the possibility of creating a new material for structural purposes and will thereby contribute to sustainability by resolving environmental issues such as carbon emissions and wasted management. Future research will be carried out to conduct further tests when the material is used in structural members.