Integrated assessment of the use of recycled concrete aggregate replacing natural aggregate in structural concrete

The use of recycled concrete aggregate (RCA) replacing natural aggregate (NA) to produce concrete named as recycled aggregate concrete (RAC) has gained increased importance in the last few decades. Despite many visible advantages associated with the initiative, RAC is not manufactured at commercial scale to replace natural aggregate concrete (NAC) used as structural concrete in Australia presently. To identify whether the production of RAC should be favoured against NAC, an integrated assessment combining multiple criteria is essential as the previous research findings provide mixed outcomes on financial viability, product performance and environmental performance. This paper uses an integrated assessment methodology employing cost-benefit analysis (CBA) which combines the financial, direct and indirect environmental, social outcomes associated with the initiative to evaluate its suitability. By combining several qualitative and quantitative studies published by the author/s, an integral result to compare the use of RCA replacing NA in structural applications is conducted in this study. Net present value (NPV) to society associated with a unit volume of RAC is evaluated as a representative indicator to compare RAC against NAC in this paper. The results state that a unit volume of RAC results in a positive NPV of 4.2-6.0% of the price of NAC for 30% replacement (and 16.3-22.6% for 100%), prior to being used in a building r. Simulation of application of the RAC to two case study buildings indicate that the average price of concrete used in the buildings is decreased by 4.1-6.1%. The results indicate that, if the external benefit associated with the production of RAC is internalised and passed on to the purchaser of the product, production of RAC in structural buildings result in a positive NPV and saving of building material costs to the contractor.