What is the maximum percentage of Recycled Concrete Aggregate (RCA) I can use in RCC?

For reinforced cement concrete (RCC) up to grade M25, a maximum of 20% of the natural coarse aggregate can be replaced with RCA (Table 3).

Can Recycled Masonry Aggregate (RMA) be used for structural concrete?

No, IS 16389 does not recommend the use of RMA in reinforced or prestressed structural concrete. Its use is limited to plain cement concrete (PCC) up to grade M20, with a maximum replacement of 20% (Table 4).

What is the maximum allowable water absorption for coarse RCA?

The maximum water absorption for coarse Recycled Concrete Aggregate (RCA) is 5.0% by mass (Table 1).

Do I need to modify the concrete mix design when using recycled aggregates?

Yes, mix design must be modified. Clause 8 states that due to higher water absorption, a two-stage mixing approach or adding extra water to compensate for absorption by the RA is recommended.

IS 16389

: 2015

Guidelines for use of demolished concrete and masonry waste as recycled aggregate in concrete

CurrentSpecializedGuidelinesBIMMaterials Science · Green Building and Sustainability

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This standard provides guidelines for using waste from demolished concrete and masonry structures as aggregate for new concrete. It classifies Recycled Concrete Aggregate (RCA) and Recycled Masonry Aggregate (RMA), specifies their required properties, and recommends permissible replacement levels for various grades and types of concrete to promote sustainability.

Provides guidelines for the utilization of construction and demolition waste as recycled aggregates, promoting circular economy principles.

Quick Reference Values

Max Water Absorption (Coarse RCA)5.0 %

Max Impurities (Coarse RCA)3 % by mass

Max RCA Replacement in RCC (upto M25)20 %

Max RCA Replacement in PCC (upto M25)100 %

Max RMA Replacement in PCC (upto M20)20 %

Max Los Angeles Abrasion Value (Coarse RCA)45 %

Practical Notes

Recycled aggregates exhibit higher water absorption than natural aggregates, which must be accounted for in mix design to maintain workability and water-cement ratio.

The source of demolition waste is critical; avoid using materials from structures contaminated with chlorides, sulphates, or other deleterious substances.

Recycled Masonry Aggregate (RMA) is generally weaker and has higher porosity than Recycled Concrete Aggregate (RCA), limiting its use to non-structural, lower-grade concrete applications.