SUMMARY OF
DBM PROCEDURE.
A comprehensive step-by-step methodology for laying Dense Bituminous Macadam (DBM) ensuring optimal durability and performance.
Sasaram (NH2)
DBM Laying
VG-30 / VG-40
Dense Bituminous Macadam Execution.
The Dense Bituminous Macadam (DBM) layer serves as a critical structural component of the pavement.
The procedure involves meticulous site preparation, precise mix design using optimal binder content (4-6%), controlled heating and mixing, followed by systematic transportation, paving, and multi-stage compaction to achieve 95-98% density.
Breakdown, Intermediate, and Finish rolling to ensure structural integrity.
Step-by-Step Execution
Methodology for DBM Laying
Site Preparation
Subgrade: Compact to 95-98% max dry density using vibratory rollers. Ensure proper profile and drainage.
Base Layer: Verify leveling and compaction if laying over WMM.
Mix Design
Aggregates: Angular, durable coarse aggregates for interlocking. Fine aggregates to fill voids.
Binder: VG-30 or VG-40 bitumen.
OBC: Optimum Binder Content 4-6%. Marshall/Superpave tests required.
Mix Preparation
Heating: Aggregates to 150°C-170°C. Bitumen to 160°C-180°C. Avoid overheating.
Mixing: Thorough blending in the asphalt plant to ensure uniform coating of all particles.
Transport & Laying
Transport: Maintain temp 150°C-160°C. Use thermal covers.
Paving: Continuous paving with asphalt paver. Thickness 40mm-75mm.
Tack Coat: Apply 0.3-0.5 kg/m² diluted bitumen if laying on existing surface.
Compaction
Breakdown: Vibratory roller (130°C-160°C).
Intermediate: Rubber-tired roller for texture.
Finish: Steel-wheel roller. Final density 95%-98%. Finish before 120°C.
Finishing & Maintenance
Surface: Check smoothness (profilograph) and skid resistance.
QC: Test binder content, gradation, and in-place density (core sampling).
Cooling: Protect from traffic until cooled to 40°C-50°C.
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Plot No 3A, Northern Peripheral Rd,
Shastri Nagar, Sector 106,
Gurugram, Haryana 122006