BIS: Enhancing Standards for Recycled Aggregates in Concrete
S. Divya, Scientist D/Joint Director, Civil Engineering Department, BIS, discusses the inclusion of C&D waste in concrete standards through IS 383:2016 and the development of guidelines for recycled aggregates. She highlights ongoing efforts to refine processing stages and maximize the use of C&D waste effectively in construction materials.
We have IS 383:2016 for aggregates used in concrete, which introduces the term "manufactured aggregates." This category includes C&D waste and other industrial byproducts. These materials can be processed and used in concrete, including PCC, RCC, and lean concrete, up to a certain percentage.
Currently, C&D waste is classified into two categories: RA (Recycled Aggregates) and RCA (Recycled Concrete Aggregates). RA includes bricks, tiles, and stones, while RCA consists of original aggregates covered with a layer of hydrated concrete paste. This paste can be removed, and the aggregates can be washed, segregated, and processed as needed.
The standard provides basic guidelines for processing these aggregates. Manufactured aggregates are expected to match the quality of conventional aggregates. They must undergo the same tests, with additional checks for alkali, sulfate, water-soluble chloride, water absorption, and specific gravity to ensure they do not negatively impact the concrete.
We are conducting further studies to refine the processing stages and revise standards and utilization values. Our goal is to maximize the use of C&D waste effectively.
Recent studies have shown that C&D waste can be utilised to an increased extent in concrete and the same will be reflected in the ongoing revision of the standard.
In addition to C&D waste, the standard also covers the utilisation of other industrial byproducts like steel slag, iron slag and copper slag, as aggregates in concrete.
