What is the maximum permissible water absorption for coarse recycled aggregate?

5.0% by mass, as per Table 1 of the standard.

What is the maximum allowed Los Angeles Abrasion value?

The maximum permitted value is 45%, according to Table 1.

Can recycled aggregate concrete be used for structural purposes?

Yes, Table 3 provides guidance on end-use, allowing it in M25 grade concrete and below for certain RCC elements, often with limitations on the replacement percentage.

What is the main difference between 'Recycled Aggregate' and 'Recycled Concrete Aggregate' in this code?

'Recycled Aggregate' is derived from waste concrete, whereas 'Recycled Concrete Aggregate' can be derived from waste concrete mixed with other materials like bricks and mortar (Clause 4).

IS 16758

: 2018

Coarse Recycled Aggregate for Use in Concrete - Specification

CurrentSpecializedSpecificationBIMMaterials Science · Aggregates and Sand

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This standard specifies the requirements for coarse recycled aggregate (CRA) produced from construction and demolition waste for use in concrete. It covers classification, quality, physical properties, grading, and testing of CRA to ensure its suitability for various concrete applications.

Specifies requirements for coarse recycled aggregates derived from concrete, masonry, or mixed debris, intended for use in concrete.

Quick Reference Values

Maximum Water Absorption5.0 % by mass

Maximum Los Angeles Abrasion Value45 %

Maximum Combined Flakiness and Elongation Index40 %

Maximum Content of 'Other Materials' (Wood, Plastic, Metal)1.0 % by mass

Maximum Content of Asphalt1.0 % by mass

Minimum Dry-rodded Unit Weight1300 kg/m³ for 20mm nominal size

Practical Notes

The higher water absorption of recycled aggregates compared to natural aggregates must be accounted for in the concrete mix design by adjusting the water content to maintain the target water-cement ratio.

The source of recycled aggregate is critical; aggregate derived purely from crushed concrete waste generally has superior properties to that from mixed demolition debris.

Careful monitoring of deleterious materials like gypsum, plastic, and soil is essential as they can negatively impact concrete strength and long-term durability.