Behavior of concrete when using RAP (Reclaimed Asphalt Pavement) as a coarse aggregate material

The construction industry is one of the fast growing industries in the world and it requires vast amounts resources to be provided to produce the infrastructure needed. As natural resources begin to deplete and are over excavated there becomes a need to find alternative solutions to provide an economical alternative and to remain sustainable. In the road construction industry asphalt is one of the most commonly used materials as a base and wearing coarse material. When the asphalt pavement reaches the end of its operational lifecycle, this material is removed from the pavement surface by the use of a rotor mill where the material that it produces is processed creating a product called reclaimed asphalt pavement (RAP). Current standards allow for the RAP to be included in the production of hot and warm mix asphalts and as an addition to a manufactured granular base materials. Concrete is the most widely used product in the construction industry and the environmental and social cost of procuring the required components is quite vast. Aggregate makes up between 60 to 80% of the total mass of the final concrete product and as natural resources begin to diminish and become more expensive to procure there becomes a need to find alternative sources for the fine and coarse aggregates. The dissertation attempts to determine if RAP could be used in concrete as a coarse aggregate replacement and if so, what is the optimum amount required to produce an economical and durable product to be used. RAP and virgin 20mm aggregate were used in proportions of 0% RAP/ 100% Virgin aggregate, 20% RAP/ 80% virgin aggregate and then incrementally the RAP percentage was increased by 20% replacing the virgin aggregate until 100% RAP was used in the design mix. Plastic and hardened state properties of the concrete were undertaken on the samples at the time of batching and 3, 7, 14, 21 and 28 day mark to determine if the inclusion of the RAP into the concrete mix would be affect the properties. From the results it could be concluded that the inclusion of RAP into the design 25MPa mix would be feasible. The optimum amount to be included would be in a 50:50 ratio, this would allow the concrete to reach its design strength while utilising the available RAP to decrease the amount of virgin aggregates required in the mix. With further testing the use of RAP in concrete could become another option for the use of recycled aggregates in concrete. As this dissertation was only based on a single 25Mpa design mix this could be expanded to determine if RAP is a viable option for higher strength mixes