Concrete and aggregates

Concrete waste is one of the highest proportions of the total construction and demolition materials. Most of the concrete waste generated is sent to landfills. Part of the concrete waste is used as recycled aggregate for producing recycled aggregate concrete; however, recycled aggregate concrete is only used on a limited basis as subgrade and in pavement applications. Depending on its quality, recycled aggregate can be employed in various civil engineering works, which can help the economic and environmental sustainability of countries. One of the downsides is the low quality of recycled aggregate. It has low density, high water absorption rate, and low strength. The existing technologies for improving recycled aggregate quality to increase its use in high-grade applications include the heating and grinding method, screw grinding method, mechanical grinding method, and gravity concentration method. The globally published data on recycled aggregate standards (normative documents) of various countries have been systematically analyzed and compared to provide producers, consumers, and researchers with a wider outlook on the properties of recycled aggregate, which are desired and specified in the legislation of various countries. This chapter may help to alleviate the concerns of consumers and further promote the use of recycled aggregate in civil engineering projects.