The below is what my natives used to do..!!
Understanding Flexible Pavement Construction: Layer by Layer
A breakdown of the essential layers involved in flexible pavement construction:
1. Subgrade (Natural Soil Layer)
🔹 Function: Acts as a foundation.
🔹 Material: Compacted natural soil.
🔹 Requirements:
🔹 Properly compacted
🔹 Free from organic/soft materials
🔹 CBR > 5% (highways)
🔹 Typical Thickness: Minimum 500 mm
2. Sub-base Course (if required)
🔹 Function: Enhances load-bearing, drainage & frost resistance.
🔹 Material: Granular Sub-base (GSB) – crushed stone, gravel, or recycled material
🔹 Thickness: 100–300 mm depending on traffic
3. Base Course
🔹 Function: Transfers load to sub-base.
🔹 Material:
🔹 Wet Mix Macadam (WMM)
🔹 Water Bound Macadam (WBM)
🔹 Thickness: 150–200 mm
4. Binder Course (Bituminous Base)
🔹 Function: Structural strength & binding.
🔹 Material: Bituminous mix – BM/DBM
🔹 Binder Content: 3.5%–5.5%
🔹 Thickness: 50–100 mm
5. Wearing Course (Surface Layer)
🔹 Function: Smooth, skid-resistant surface
🔹 Material: Bituminous Concrete (BC) or SDBC
🔹 Binder: VG-30 or VG-40 grade bitumen
🔹 Thickness: 25–50 mm
Optional Coats (for bonding & waterproofing):
🔹 Prime Coat: On granular base before bitumen
🔹 Tack Coat: Between bituminous layers
🔹 Seal Coat: Final waterproofing layer
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