Bituminous Work

Top 9 Proven Steps for Bituminous Concrete (BC) | MoRTH Clause 507 Top 9 Proven Steps for Bituminous Concrete (BC) Construction Quick Summary: Bituminous Concrete (BC) is the final wearing course of flexible pavement laid in 30–50 mm thickness over DBM or bituminous base. Construction shall strictly follow MoRTH Clause 507, including approved mix design, controlled laying temperature, proper compaction and quality control tests. 1. Scope Methodology for laying of DBM in this project is detailed herein under. This method statement is based on parameters conforming to MoRTH, MS-2 Specifications. The construction of pavement layers on existing road involves the dismantling of existing bituminous layers, widening and strengthening of the existing road. This work covers preparation of surface, tack coat application, production of BC mix, transportation, laying, compaction, joint treatment and quality control testing in accordance with MoRTH Clause 507. 2. Reference Standards MoRTH Specifications – Clause 507 (5th Revision) IRC: SP: 84 – Manual of Specifications IS: 73 & IS: 15462 – Bitumen Standards IS: 2386 (All Parts) – Aggregate Testing Standards ASTM / AASHTO and MS-2 7th Rev– Marshall Mix Design Top Level Sheet – DBM (Dense Bituminous Macadam): Approved Mix Design & Approved GFC Drawings 3. Equipment Required Hot Mix Plant with automatic controls Self-propelled sensor paver with electronic, tamping/vibrating extendible screed (as per Clause 501.5) Tandem vibratory rollers Pneumatic Tyred Roller (PTR), 12–15 tonnes with minimum tyre pressure of 5.6 kg/cm² Bitumen pressure distributor/sprayer with accessories (as per Clause 502.4.1) Mechanical broom and air compressor for surface cleaning Core cutting machine for density testing Sufficient number of tippers for continuous and uninterrupted laying Materials & Job Mix Design Test Procedure of DBM & BC Mix Design (as per MoRTH & IRC Specifications) 1: Raise RFI for sampling of aggregates for DBM/BC mix design. 2: Sample the cold bin individual aggregates jointly. 3: Conduct individual gradation for aggregate as mentioned in MoRTH 500-10. 4: Blend the aggregate to meet the specified limits as mentioned in MoRTH 500-10. 5: Conduct the tests for aggregate to confirm its suitability for asphalt mix works: 6: AIV or LAAV, FI & EI, Stripping value, Water Absorption, Sand Equivalent value test to meet its suitability for DBM & BC as mentioned in MoRTH. 7: Feed the cold bin blending aggregate proportion in the Hot Mix Plant & take the individual hot bin aggregates. 8: Conduct specific gravity & water absorption test in the hot bin aggregates. 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No. 9: Conduct the individual gradation for aggregate & blend the aggregate to achieve the limit specified in MoRTH Table 500-10. 10: Feed the obtained blending proportion in the Hot Mix Plant and take the combined mix sample and check the combined gradation tests as mentioned in MoRTH 500-10. 11: Conduct the following tests for bitumen: Softening Point Test, Penetration Test, Viscosity Test from the approved bitumen source. 12: Prepare the mix with different binder content & find the Maximum Specific Gravity of the mix as per ASTM D-2041. 13: Cast the Marshall moulds with different binder content to check VMA, VFB, GSA, Air Voids, Stability & Flow of the mix. 14: With the obtained result plot the graph for Bulk Density, Marshall Stability, Air Voids, Flow, VMA & VFB. 15: All test data are interpreted & marked at which % all criteria passes. 16: Optimum Binder Content (OBC) has been found from chart. 17: Retained Stability Test conducted at OBC. 18: Refusal Density of the BC mix to be checked at 75, 150, 300 blows. 19: Marshall Quotient found for BC as per Table 7 of IRC SP:53-2002. 20: Confirmatory moulds casted & tested for Stability, Flow, VFB, VMA. Bituminous material of VG-40 grade shall confirm to the specifications of IS-73(2013). If modified binder is used then CRMB / PMB conforming to the requirement of CL.501.2.1, 507.2.1, IRC-SP-53-2010 and IS 15462-2004. Approved Aggregate and filler shall confirm two of MoRTH Cl.501.2 & Cl.507.2. Job Mix Formula (JMF): The Job Mix Formula (JMF) for Bituminous Concrete (BC) shall be developed and approved for use in the works in the presence of the Authority Engineer. The JMF shall include the following details: Source and location of all materials (bitumen, coarse aggregate, fine aggregate, and filler) Proportions of all constituent materials Binder type and percentage by weight of total mixture Coarse aggregate, fine aggregate, and mineral filler percentage Combined grading with specified sieve passing limits as per BC requirements Marshall test results as per Table 500-11 (Stability, Flow, Density, Air Voids, VMA, VFB) Aggregate compliance with MoRTH Clause 501.2 & Clause 507.2 Mixing, laying, and compaction temperature ranges Optimum Bitumen Content (OBC) and volumetric properties of mix Job Mix Design for BC shall be conducted in the Field Laboratory using Marshall Method. The materials shall be collected directly from the stockyard / storage tank and shall be checked for various physical requirements. The testing shall be carried out in the presence of the Consultant and submitted for approval. Approval of JMF: Approval shall be based on witnessed testing by the Independent Engineer. Samples shall be tested in in-house QC lab. Any change in material source requires submission of new JMF for approval prior to execution. Plant Trials: After laboratory approval, plant trials shall be conducted to ensure uniform mix production. Permissible variations shall comply with Table 500-13 limits. Laying Trials: Once the plant trials have been successfully completed and approved, the laying trials are executed to demonstrate that the proposed mix can be successfully laid and compacted in accordance with Clause 501. The laying trial shall be carried out on a suitable area which is not to form part of the works. The area of the laying trials shall be a minimum of 100 sq. m. of construction similar to that of the project road, and it shall be in all respects, particularly compaction, the same as the project construction, on which the bituminous material is to be laid. Information to AE is given of the proposed method for laying and compacting the material. The density

Bituminous Concrete (BC) Profile Corrective Course – Construction Methodology | MoRTH 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 Sl. No. Equipment Quantity 1 Batch Type Hot Mix Plant (150–200 TPH) 01 2 Sensor Paver with Electronic Screed Control 01 3 Tandem Vibratory Roller 02 4 Pneumatic Tyred Roller 01 5 Bitumen Pressure Distributor 01 6 Mechanical Broom / Air Compressor 01 7 Tipping Trucks As required 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. Frequently Asked Questions – BC Profile Corrective Course Purpose of BC PCC? To correct minor profile defects and improve riding quality. Typical thickness? 30–50 mm. Where used? Rutting, shallow depressions, uneven surface. Material? Bituminous Concrete as per MoRTH Clause 509. Tack coat rate? 0.20–0.25 kg/m². Compaction? Tandem roller + PTR. Joint treatment? Full depth cut with hot bitumen painting. Traffic opening? After minimum 24 hours.