Guidelines for the use of Construction and Demolition Waste in the Road Sector
2017 Edition

IRC 121 (Clause 7.1) recommends several key steps for preparing C&D waste for road use: Firstly, segregate waste at source to remove soil, wood, plastics, and metals. Metallic components like steel and wires should be extracted before or during demolition. Glass and ceramic tiles can remain but require careful handling. Next, crush the debris using jaw crushers or manually where suitable, reducing it to the desired size. Then, verify the particle size distribution against specifications and perform mechanical sieving if necessary. Mechanical stabilization, such as mixing particles with tractor-driven rotavators, improves compaction. These processed materials are then used in granular sub-base, base layers, cement-stabilized layers, concrete pavements, paving blocks, and kerbs. This process ensures quality recycled aggregates and aligns with sustainable international practices.

Per IRC 121 Clause 1.5, the maximum particle size for crushed C&D waste in earth embankments should not exceed 75 mm. For rockfill embankments, particles up to 300 mm are permissible, provided satisfactory compaction in the field can be demonstrated. If crushing to 75 mm is not cost-effective, the engineer may approve larger sizes up to 300 mm. Additionally, side slopes must be protected with a suitable earth cover thickness based on embankment height to prevent erosion—for example, 0.5 m cover for embankments under 1 m tall, scaling up to 1.5 to 2 m for heights over 3 m. Embankments 6 m or taller require stability design as per IRC:75, with a conservative internal friction angle of 40°. Use of C&D waste in reinforced soil walls is discouraged to maintain structural integrity.

IRC 121 permits replacing natural mineral aggregates with recycled concrete aggregate up to 30% in rigid pavements such as plain cement concrete (PCC) and roller compacted concrete pavements (RCCP) for rural and urban colony roads with traffic less than 200 vehicles per day. This substitution applies to concrete grades up to M30; higher grades (M40 and above) are not recommended for RCA use in pavements. For kerb stones and paving blocks in light traffic areas, RCA can replace up to 100% of natural aggregates given the compressive strength criteria are met. Additionally, in dry lean concrete base courses, RCA replacement can reach 30%. Mix designs must ensure the combined gradation of RCA and natural aggregates meets required standards to maintain durability and performance.

Ensuring durable roads with C&D waste involves comprehensive quality control measures as highlighted in IRC 121. These include: sorting and removing organic matter, plastics, metals, chlorides, and sulphates exceeding acceptable thresholds before processing; crushing and grading the waste to match specified particle size distributions, often via mechanical sieving; confirming aggregate strength and stability through tests like Aggregate Crushing Value (ACV), Aggregate Impact Value (AIV), and California Bearing Ratio (CBR); designing cement-stabilized mixes to meet minimum compressive strengths (1.7 MPa for sub-base, 3.0 MPa for base course at 7 days); implementing proper concrete mix designs with optimum water, cement, and admixture ratios; and adopting a two-stage mixing process for uniformity. Regular testing and documentation assure compliance with IRC and MORTH/MORD standards, safeguarding structural integrity and sustainability.

Yes, IRC 121 explicitly restricts the use of processed C&D waste, including recycled aggregates (RA) and recycled concrete aggregates (RCA), in prestressed concrete and structural or load-bearing concrete elements like bridges, culverts, and flyovers. This is due to variability in strength, durability concerns, and potential contamination. The code endorses C&D waste primarily for embankments, sub-base and base courses, cement concrete pavements up to M30 grade in low traffic roads, kerb stones, paving blocks, and dry lean or roller compacted concrete applications. RCA usage beyond 30% replacement for concrete grades above M30 is not recommended. These restrictions are vital to ensure safety and performance of critical infrastructure components.