Self-compacting concrete produced with recycled concrete aggregate coated by a polymer-based agent: A case study

Understanding the effects of recycled concrete aggregate (RCA) and polymer impregnation on the properties of self-compacting concrete (SCC) is crucial for the construction industry's efforts to reduce environmental impact and utilise recycled materials. This study aims to examine the impact of RCA inclusion and polymer impregnation on the properties of SCC, in response to the urgent demand for sustainable construction practices. Two different methods of polymer impregnation were evaluated to assess their impact on the workability and hardened characteristics of SCC. The SCC mixtures were prepared using river sand (natural fine aggregate (NFA)), natural crushed limestone (natural coarse aggregate (NCA)) and a polymer impregnation level of 0.05 wt% of the water content, with a water-to-cement ratio of 0.34. RCA was used as a complete replacement for NFA and NCA, adhering to the American Society for Testing and Materials (ASTM) C33 standards for recycled fine concrete aggregate (RFCA) and recycled coarse concrete aggregate (RCCA)The workability of the SCC mixtures was evaluated based on the criteria set by the European Federation of National Associations Representing for Concrete (EFNARC). Among the hardened properties, the compressive strength of the hardened properties was tested at four different time intervals (1, 3, 7 and 28 days), and the integrity of the SCC specimens was assessed using ultrasonic pulse velocity. The polymer impregnation process resulted in a slower compressive strength development rate compared to that observed in the control concrete. However, combining polymer impregnation type 1 with either RFCA and NCA or RCCA and NFA significantly increased the 28-day compressive strength by 5.02% and 1.80%, respectively. These findings provide valuable insights into the behaviour of SCC incorporating RCA and polymer impregnation. Optimising the selection and combination of materials can enhance the performance and sustainability of SCC in construction applications.