Use of recycled aggregate in concrete application: Case studies

This paper describes initial findings of work undertaken to demonstrate the suitability of coarse recycled aggregate for use in concrete paving applications. During this work, scientific and applied research was combined. Recycled aggregates obtained from a local aggregate supplier were used. Concrete was produced using blend of natural gravel and up to 100% recycled aggregate contents. All mixes were designed for equivalent 28-day compressive cube strength of 30 and 35 N/mm 2 for specific paving applications- PAV1 and PAV2 mixes respectively. In the first instance fresh, engineering and durability performance of concrete was assessed. Fresh property results showed no effect due to the coarse RCA inclusion with results remaining within the required tolerance of ±20 mm. The study of engineering properties showed similar performance (strength development, flexural strength, static modulus of elasticity, drying shrinkage and swelling) between two types of concrete. Durability performance (near surface absorption, carbonation (CO 2) penetration, freeze thaw scaling, resistance to chloride ingress and abrasion) of RCA concrete was assessed and results for RCA equivalent strength concrete were very similar to NA concrete