IRC 107:2013 is the Indian Standard (IRC) for specifications for bituminous concrete (bc), bc (ac) as wearing course on roads. IRC 107:2013 specifies Bituminous Concrete (BC) — the premier dense-graded wearing course for Indian flexible pavements. BC 13 (13 mm maximum aggregate) is widely used for urban arterials and moderate-traffic highways; BC 19 (19 mm) for heavier-duty corridors. IRC 107:2013 covers every aspect from aggregate source to acceptance: crushing value ≤ 30%, Marshall stability ≥ 12 kN, binder content 5.0-6.5%, field density ≥ 98% of target, and rutting resistance verification. The specification interfaces tightly with [IRC 37:2018](/code/IRC-37-2018) pavement design (where BC properties are the elastic modulus input) and [IS 73](/code/IS-73-2013) bitumen specifications. Every modern Indian NH / SH BC laying is governed by IRC 107 or the closely-aligned IRC 29:2019 (Dense Bituminous Concrete). The specification bridges the gap between laboratory research and field practice — giving engineers clear, enforceable criteria for pavement quality.
Specifies the materials, mix design, production, laying, compaction, and acceptance of Bituminous Concrete (BC), Asphalt Concrete (AC), and similar dense-graded bituminous wearing courses used on Indian roads and highways.
Bituminous Concrete wearing-course mix design, Marshall properties, gradation and field control.
| Reference | Value | Clause |
|---|---|---|
| Bituminous Concrete (BC) — purpose | Wearing course (top layer) | Cl. 1.1 |
| BC Grade 1 — nominal max aggregate size | 19 mm (layer thickness 50-65 mm) | |
| BC Grade 2 — nominal max aggregate size | 13.2 mm (layer thickness 30-40 mm) | |
| BC — minimum bitumen content (Grade 1) | 5.2% by mass of mix | Table 3 |
| BC — minimum bitumen content (Grade 2) | 5.4% by mass of mix | Table 3 |
| Bitumen grade — typical | VG-30 / VG-40 / Modified (CRMB / PMB / NRMB) | Cl. 3.2 |
| Marshall stability — min (VG-30, 60 °C) | ≥ 9.0 kN | Table 3 |
| Marshall stability — modified bitumen | ≥ 12.0 kN | Table 3, Note (i) |
| Marshall flow — range | 2.5-4.0 mm | |
| Air voids — design (compacted) | 3-5% | Table 3 |
| VMA — minimum (NMAS 19 / 13.2) | 13% / 14% | Table 100-12 |
| VFB | 65-75% | Table 100-12 |
| Mix temperature — VG-30 / VG-40 | 150-165 °C / 160-175 °C | Cl. 10.4.1 |
| Mix temperature — modified bitumen | 165-180 °C | Cl. 10.4.1 |
| Laying temperature — min at paver (VG-30) | 130 °C | Cl. 10.4.3 |
| Aggregate — LA Abrasion max | ≤ 30% | Table 100-10 |
| Aggregate — flakiness + elongation max | ≤ 35% | Table 100-10 |
| Aggregate — water absorption max | ≤ 2% | Table 100-10 |
| Stripping value — coating retained min | ≥ 95% (water sensitivity) | Table 100-10 |
| TSR — moisture susceptibility | ≥ 80% | Table 100-12 |
| Field density — % of lab Marshall | ≥ 98% | |
| Roughness — IRI (post-laying max) | ≤ 2.0 m/km (NH new construction) | Cl. 10.7.2 |
IRC 107 (2013) provides Specifications for Bituminous Concrete (BC) — BC (AC) — as Wearing Course on Roads — specifically focused on the top-most bituminous layer of a flexible pavement, the layer that vehicles run on directly. It complements IRC:29:2019 (which covers both DBM + DBC binder + wearing courses) by providing detailed specifications for the wearing course application.
Use IRC 107 when you are: - Specifying the bituminous concrete (BC) wearing course on a flexible pavement (NH, SH, expressway, urban arterial) - Doing detailed BC mix design for a heavy-traffic project - Cross-referencing wearing course performance in pavement design per IRC:37:2018 - Specifying dense-graded asphalt as the riding surface - Comparing BC against gap-graded mixes (SMA per IRC:SP-79, CRMB per IRC:SP-107:2015) - Doing rehabilitation / overlay on existing pavement requiring new BC layer
What IRC 107 covers: - Aggregate properties + gradation for wearing course - Bitumen grade for wearing course (typically VG-30 or VG-40) - Mix design via Marshall method - Volumetric requirements (Va, VMA, VFB) - Stability + flow + tensile strength ratio - Mixing temperatures + plant operation - Transport + paving requirements - Compaction + density specification - Quality control + acceptance criteria - Surface texture + skid resistance
BC wearing course faces unique demands compared to binder course (DBM):
1. Direct traffic loading + tyre interface — must resist surface rutting, polishing, ravelling 2. Weather exposure — UV, rain, freeze-thaw (in colder climates), thermal cycling 3. Surface texture for skid resistance — coarse enough for tyre grip 4. Smooth riding surface — for comfort + fuel economy + vehicle dynamics 5. Drainage — proper cross-fall + water shedding 6. Aesthetics — uniform appearance after construction + over service life
Differences from DBM binder course: - Smaller maximum aggregate (typically 13.2 mm or 9.5 mm) for finer surface - Higher binder content (5.0-6.0 % vs 4.0-4.5 % for DBM) - Lower voids in mineral aggregate (VMA) for denser surface - Stricter aggregate properties (polishing value, soundness) - Tighter Marshall stability for permanent deformation resistance - Smaller layer thickness (25-50 mm vs 50-100 mm for DBM)
Design life of BC wearing course: - High-volume NH (AADT > 5,000 commercial vehicles/day): 6-8 years - Medium-volume SH (AADT 2,000-5,000): 8-12 years - Low-volume district / rural (AADT < 2,000): 12-15 years - Expressway / 6-lane NH: 8-10 years with modified bitumen - After this period: resurface (new BC layer over existing)
Critical performance properties: 1. Stability (resistance to lateral spreading) — Marshall ≥ 10 kN 2. Air voids + density — Va 3-5 % for optimum durability + performance 3. Polishing value — ≥ 40 BPN for skid resistance over time 4. Tensile strength ratio (TSR) — ≥ 0.80 for moisture resistance 5. Stripping resistance — ≥ 95 % retained binder coating after immersion test 6. Surface texture (mean profile depth) — 0.6-1.0 mm for wet skid
Aggregate gradation envelope (BC, 13.2 mm max aggregate — most common): - 19 mm sieve: 100 % - 13.2 mm: 90-100 % - 9.5 mm: 75-90 % - 4.75 mm: 50-70 % - 2.36 mm: 30-50 % - 0.6 mm: 12-22 % - 0.3 mm: 8-15 % - 0.075 mm: 4-8 %
Alternative gradation for BC, 9.5 mm max aggregate (finer): - 13.2 mm: 100 % - 9.5 mm: 90-100 % - 4.75 mm: 60-75 % - 0.075 mm: 5-9 %
Aggregate properties (BC wearing course): - Los Angeles abrasion: ≤ 30 % (stricter than DBM) - Aggregate impact value: ≤ 24 % (stricter) - Crushing value: ≤ 27 % - Polishing value (wet): ≥ 45 BPN (higher than DBM for skid) - Flakiness + elongation: ≤ 30 % combined - Soundness (Sodium sulphate, 5 cycles): ≤ 12 % - Stripping resistance: ≥ 95 % retained - Water absorption: ≤ 2 % - Specific gravity: 2.6-2.9 (typically) - Sand equivalent: ≥ 50
Filler (limestone powder / hydrated lime / cement): - Acceptable type 1: ≤ 75 µm; passing 0.075 mm sieve 100 % - Filler dosing: 2-5 % by mass of dry aggregates - Function: void filling + improved binder adhesion + anti-stripping
Bitumen specifications: - VG-30 (penetration 50-70): standard for plains, NH/SH - VG-40 (penetration 35-50): heavy traffic / high temperature - Modified bitumen alternatives: - CRMB-55 / CRMB-60: for very high traffic NH wearing course - PMB-70 / PMB-120: polymer modified, premium - per IRC:SP-53:2010 - Penetration test result, ductility, softening point: per IS 73 + IS 1206
Marshall mix design parameters: - Optimum binder content: target Va = 4 % at design point - Air voids (Va): 3-5 % (allowable range) - VMA (Voids in Mineral Aggregate): ≥ 14 % (13.2 mm); ≥ 15 % (9.5 mm) - VFB (Voids Filled with Binder): 65-78 % - Stability (Marshall): ≥ 10 kN (preferred; some heavy-NH projects spec ≥ 12 kN) - Flow: 2-4 mm - Tensile Strength Ratio (TSR, moisture susceptibility): ≥ 0.80 - Stiffness modulus (S_BIT): ≥ 2,500 MPa at 25 °C
Construction temperatures: - Mixing temperature: 155-170 °C (VG-30); 170-180 °C (VG-40) - Transport + laying: 5-15 °C above paving min - Paving temperature: 140-160 °C minimum at paver - Compaction completion: must finish before mix < 120 °C
Layer thickness: - Single BC layer (typical NH): 40-50 mm - Double BC layer (heavy traffic): 25-30 mm + 25 mm = 50-55 mm total - Thin overlay: 30-40 mm - Layer thickness ≥ 2.5-3 × max aggregate size
Tack coat (between BC + underlying binder): - Bitumen emulsion (RS-1 / SS-1) per IS 8887 - Application rate: 0.20-0.40 kg/m² (residue basis) - Spray within 5 m of paver position - Curing: 30-60 min before paving
Compaction + density: - Field density (in-place): ≥ 95 % of Marshall density (acceptable); ≥ 96-97 % for high-traffic NH - Density measurement: nuclear gauge + cores (verification) - At joints: within 1 % of mid-mat density - Roller sequence: typically: - Static rolling (1-2 passes) immediately after paving - Vibratory rolling (4-6 passes) for primary compaction - Finishing pass (1-2 static) to smooth surface
Acceptance criteria: - Density: ≥ 95 % Marshall density on minimum 90 % of measurements - Layer thickness: ± 6 mm of design (compacted) - Surface level: ± 6 mm of design - Surface evenness: 3 mm max under 3-m straight-edge (longitudinal) - Cross-fall: ± 0.5 % of design - Skid resistance (BPN test): ≥ 50 BPN at 28 days
Surface texture: - Mean Profile Depth (MPD): 0.6-1.0 mm - Mean Texture Depth (MTD): 0.5-0.8 mm - For higher-speed roads + wet-skid concerns: higher texture target
Maintenance + life-extension: - Surface dressing / micro-surfacing at year 5-7: refresh texture + skid - BC overlay at year 8-12: new wearing course over existing - Full reconstruction at year 25-30: if structural pavement has deteriorated - Continuous monitoring: IRI roughness + skid + visual distress + FWD
1. Aggregate polishing value too low. Aggregate polishes smoothly under traffic; skid resistance drops below limit within 2-3 years. Mandatory polishing value ≥ 40 BPN (≥ 45 for high-traffic NH). 2. Binder content under-spec. Marshall design at 5 % binder; mix produced at 4.5-4.7 %; mix dry + raveling + cracking. Strict binder dosing + extracted samples per batch. 3. Filler / fines content wrong. Filler at 1-2 % (low) → VMA exceeded + segregation. At 7-8 % (high) → low VMA + low binder effective volume. Target 2-5 %. 4. Mix temperature too low at paver. Mix arrives at 130 °C, compaction window short, under-compaction; density < 95 %. Insulated transport + acceptance temperature ≥ 140 °C. 5. No TSR test. Wearing course laid without moisture sensitivity verification; first monsoon causes stripping + ravelling. Mandatory TSR ≥ 0.80 + anti-stripping agent if needed. 6. Tack coat skipped at layer interface. Bond between DBM + BC fails; delamination + scuffing in 6-12 months. Tack coat 0.20-0.40 kg/m² mandatory. 7. Joint construction inadequate. Cold joints at layer ends not properly bonded; density at joints below 95 %; longitudinal cracking. Tackle joints with hot mix overlap. 8. Laying in cold weather (< 10 °C). Temperature loss too fast; localised cool spots; uneven density. Avoid cold laying; use insulated transport. 9. Layer thickness inadequate. Below 25 mm for 13.2 mm aggregate; aggregate breaks during rolling; texture rough. Minimum 30 mm for 13.2 mm mix. 10. No surface texture measurement at handover. Texture not measured; smooth surface at handover but actual texture inadequate; skid concern later. Mandatory MPD measurement + retro-reflectivity at acceptance. 11. Aggregate quality inconsistent between batches. Two suppliers; properties differ; mix performance varies. Single supplier per project + acceptance testing per batch. 12. Modified bitumen not stored properly. CRMB / PMB at 175+ °C for > 24 hrs; rubber / polymer separates; mix performance degraded. Storage ≤ 8 hrs at controlled temperature. 13. Old binder used. Bitumen aged in storage; reduced ductility; mix performance below design. Use fresh bitumen; check on receipt. 14. Marking material incompatible with surface. Standard paint chips off some surfaces; markings fail in 6 months. Specify marking material compatible with surface; pre-deploy spec. 15. Maintenance neglected. Year 5+ surface dressing skipped; texture polishes; skid drops. Schedule micro-surfacing or chip-seal at year 5-7. 16. Sub-layer (DBM) inadequate. Wearing course OK but underlying DBM poor; pavement structurally inadequate; rutting accelerated. BC alone doesn't solve sub-structural issues.
Bituminous wearing course project — IRC 107 touchpoints:
1. DPR / pavement design (per IRC:37:2018): wearing course thickness + material specification.
2. Mix design (laboratory): - Aggregate gradation within IRC 107 envelope (13.2 mm BC most common) - Bitumen grade selection (VG-30/40 + modified options per traffic + climate) - Marshall test at trial binder contents (4-6 %) - Volumetric verification (Va = 3-5 %, VMA ≥ 14 %, VFB 65-78 %) - Stability ≥ 10 kN + flow within range - TSR ≥ 0.80 - Polishing value verification - Final mix proportion design
3. Plant setup: - Batch / drum mixer capable of 155-175 °C - Storage tanks for bitumen + filler - Calibrated aggregate + bitumen dosing - QC laboratory on-site for batch testing
4. Trial section: - 100-200 m on representative subgrade + DBM - Validate plant output + paver + roller pattern - Adjust as needed - Cores for density + mix-design conformance
5. Mass production: - Plant mix at 155-170 °C - Transport in covered insulated dumpers within 1.5-2 hrs - Tack coat 0.20-0.40 kg/m² ahead of paver - Paver-laid at 140-160 °C - Roller sequence: static → vibratory → finish; complete before 120 °C
6. Quality control + acceptance: - Plant: aggregate gradation + binder content + temperature per batch - Site: laying temperature + roller pass count + density (nuclear + cores) - Cores: 1 per 1000-2000 m²; thickness + density + extracted binder content - Surface: texture + evenness + skid resistance
7. Opening + first-year monitoring: - Surface inspection for ravelling, segregation, flushing - First monsoon stripping check - Skid resistance after first dry season
8. Operations + maintenance: - Annual visual inspection - 5-year: surface texture + skid resistance + structural FWD/BBD check - Mid-life: micro-surfacing or chip-seal to refresh texture - 8-15 year design life; resurfacing with new BC overlay when rutting > 10 mm or polishing reduces skid below limit
IRC 107 is the wearing-course detail specification complementing IRC 29 — every modern NH 4/6-lane project, every state-highway upgrade, and every urban-arterial improvement applies its framework to the topmost bituminous layer.