Evaluation on the Surface-Modified Recycled Coarse Aggregate for the Development of Sustainable Pavement Quality Concrete

The construction industry generates a huge amount of concrete waste that needs to be recycled, which is said to be recycled aggregate (RA) being used for partial or total substitution of natural aggregate. Upscaling recycled aggregate in concrete production reduces dumped waste and decreases energy consumption in the extraction of new materials. However, the high water demand and poor interfacial transition zone of recycled aggregate contribute to inferior compressive strength and durability properties of concrete. Therefore, in this study, the inherent properties of recycled aggregate are improved by precoating it with pond ash material discarded from the thermal power plant industries. The pretreated recycled aggregate is then used in the replacement of natural coarse aggregate at various substitution levels (0%, 30%, 50%, 70%, and 100%), and the effects of these replacements on the mechanical and durability aspects of concrete are explored. The compressive strength, flexural strength, elastic modulus, water absorption, water sorptivity, and carbonation properties are assessed in pretreated recycled aggregate concrete. Test results indicate an increase in compressive strength (20.68%) and flexural strength (13.33%) in concrete with 50% pretreated recycled aggregate, while the elastic modulus in the same replacement shows marginal improvement. Durability aspects such as water absorption and sorptivity were enhanced with the precoated RCA and fell within permissible limits. Recycling construction and demolition waste using this pretreatment technique can help to protect the environment and reduce the depletion of natural resources, contributing to sustainable development goals.