Profile Corrective Course Using Bituminous Concrete (BC) – Construction Methodology

Bituminous Concrete (BC) Profile Corrective Course is a thin, dense graded bituminous layer laid to correct minor surface undulations, rutting, shallow depressions and riding quality issues prior to or as part of the final wearing course.

1.0 Scope and Surface Preparation

This work consists of providing a Profile Corrective Course using Bituminous Concrete of variable thickness, generally ranging from 30 mm to 50 mm, to restore the pavement profile as per approved longitudinal and cross levels.

1.1 Existing Bituminous Surface

• Repairs: Potholes, cracks, ravelled areas repaired as per MoRTH Clauses 3004.2 & 3004.3.
• Milling / Scarifying: Where required, shallow milling carried out to remove surface irregularities.
• Cleaning: Surface cleaned using mechanical broom and air compressor.
• Tack Coat: Uniform tack coat applied prior to BC laying.

1.2 Existing Granular Surface (If Applicable)

• Surface made firm, even and free from loose materials.
• Priming carried out as per MoRTH Clause 502.
• Tack coat applied after priming and curing.

1.3 Pre-Laying Level Checks

Existing levels shall be checked jointly with Engineer’s representative and recorded to determine thickness and extent of profile correction.

2.0 Plant, Machinery & Equipment

3.0 Materials & Mix Design

3.1 Materials

• Coarse & fine aggregates conforming to MoRTH Table 500-18
• Bitumen: VG-30 / VG-40 / Modified Bitumen (as per contract)
• Mineral Filler: Cement / Lime / Stone Dust
• Tack Coat: Rapid Setting Cationic Bitumen Emulsion

3.2 Job Mix Formula (JMF)

BC mix design shall be carried out using the Marshall Method as per MoRTH Clause 509. Approved JMF shall specify grading, binder content, temperature limits and target density.

3.3 Hot Mix Plant Operation

• Bitumen temperature: 150–165°C
• Aggregate temperature: 150–170°C
• Mix discharge temperature: 140–165°C
• Uniform coating ensured with controlled mixing time

4.0 Laying & Compaction

4.1 Transportation of Mix

• BC mix transported in insulated, tarpaulin-covered trucks.
• Truck beds coated with approved release agent.
• Temperature at paver hopper: ≥135°C.

4.2 Tack Coat Application

• Application rate: 0.20–0.25 kg/m² on bituminous surface.
• Applied by calibrated mechanical sprayer.
• Laying commenced only after tack coat breaks.

4.3 Laying & Finishing

• Sensor wire fixed at 10 m intervals for level control.
• Minimum laying temperature: 130°C.
• Loose thickness allowance: approx. 20–25%.
• Manual finishing permitted in confined or irregular areas.

4.4 Compaction

• Initial rolling by tandem vibratory roller.
• Intermediate rolling by PTR.
• Final finish rolling by static tandem roller.
• Rolling continued till specified density achieved.
• Transverse joints cut full depth and edges painted with hot bitumen.

5.0 Quality Control & Traffic Management

• Core cutting after 24 hours for density verification.
• Marshall properties verified as per approved JMF.
• Surface regularity and levels checked as per Clause 902.
• Traffic opened minimum 24 hours after completion.
• Traffic diversion with barricades, cones and flagmen.