BIS: Integrating C&D Waste into Building Materials with Quality Control
Sanjay Pant, DDG, BIS, discusses the integration of C&D waste into building materials, focusing on standards and the challenges of maintaining quality, particularly in durability and consistency. He mentions the revisions to IS 383, which now include provisions for using C&D-derived aggregates.
Aggregate from Construction and Demolition (C&D) waste falls under the category of recyclable materials. For instance, there are various types of cement today that utilize fly ash or slag as supplementary cementitious materials, which can also be incorporated directly into concrete. Additionally, we have a range of other materials like bricks and blocks, and significant innovations have been made in this area. For example, there are standards like IS 12894 for fly ash lime bricks, IS 13757 for fly ash clay bricks, and IS 16720 for fly ash cement bricks. These standards support the extensive use of fly ash. Other examples include concrete blocks, both hollow and solid, lightweight aggregate-based blocks, preformed foamed concrete blocks, and autoclaved aerated concrete (AAC) blocks. There's also IS 12440, which allows the use of stone waste to partially replace concrete matrices, leading to the production of stone concrete masonry blocks.
However, the key question is: can these materials also incorporate aggregates derived from C&D waste? Can concrete be produced using, or should it use, C&D-based aggregates along with fly ash or slag? This is a complex topic with many potential applications, but also challenges, particularly regarding durability. Nevertheless, significant progress has been made in utilizing fly ash and slag on a large scale in the country. The combination of aggregates is another critical consideration. IS 383 is the Indian Standard that specifies requirements for aggregates for concrete from natural sources. This standard was revised around 2016, and we received extensive feedback and suggestions for improvement.
Given the rapid increase in construction activities and the corresponding generation of C&D waste after 2014, the possibility of using C&D-derived aggregates was widely discussed. One of the solutions proposed was to retrieve and convert C&D waste into aggregates. The challenge was whether a specification for aggregates derived from C&D waste could be developed. Instead of creating a separate specification, we decided to incorporate these provisions into IS 383. Since IS 383 is referenced in all types of concrete specifications and codes of practice, we revised it once more to include guidelines for the use of C&D-based aggregates, rather than publishing a separate standard.
