Standard Operating Procedure for Granular Sub Base (GSB) road construction, ensuring stability, durability, and compliance with industry standards and IS Codes.
To define a structured procedure for Granular Sub Base (GSB) road construction, ensuring stability, durability, and compliance with industry standards and IS Codes.
This SOP applies to all GSB road construction projects, covering material selection, preparation, laying, compaction, quality control, and testing procedures as per relevant IS codes.
Ensures compliance with specifications, IS codes, and project timelines
Monitors execution & verifies compliance with drawings
Ensures availability of materials, tools & workforce coordination
Perform material spreading, grading, and compaction
Checks material quality, layer thickness, and compaction density
Ensures all safety measures are followed at the construction site
Aggregates, crushed stone, sand, gravel as per IS 383:2016
For compaction as per IS 456:2000
If required for stabilization
Excavator, loader, dumpers, grader
For moisture control during compaction
Vibratory or static roller
Tape, level indicators, survey tools
Core cutter, sand replacement apparatus, moisture meter
Sieve analysis as per IS 2386 to verify material gradation requirements
Check thickness at min. 3 locations per 500 sq.m (tolerance: ±10mm)
Field density tests (minimum 98% MDD) at 1 test per 500 sq.m
Verify moisture content (OMC ±2%) using rapid moisture meter
Maximum 8mm deviation under 3m straight edge
Check crossfall (2-2.5%) and longitudinal grade as per design
Impact, abrasion, and flakiness index tests as per IS standards
Verify drainage pattern after completion using water flow tests
Safety boots, gloves, helmets, and high-visibility vests for all personnel
Ensure proper barricading and warning signs around work areas
Control traffic movement during material transportation and construction
Maintain safe distance between working equipment and personnel
First aid kits and trained personnel available on site at all times
Clear communication protocols between equipment operators and ground staff
Daily inspection of all equipment before operation
Regular hydration breaks and shade provisions during hot weather
Problem: Separation of coarse and fine aggregates during transportation or spreading.
Solution: Remix material using grader or dozer, control dump heights during unloading, ensure proper moisture content before spreading, and adopt proper spreading techniques to minimize segregation.
Problem: Areas failing density tests despite multiple roller passes.
Solution: Adjust moisture content to OMC, increase number of roller passes, reduce layer thickness if too thick, check roller functionality and vibration settings, consider different roller types for problematic materials.
Problem: Uneven surface with depressions or high spots after compaction.
Solution: Scarify affected areas, add or remove material as needed, reshape to proper profile, and recompact. Ensure proper control of grader operations and frequent level checks during spreading.
Problem: Material too dry (dusty) or too wet (pumping).
Solution: For dry material, add water in controlled amounts with uniform distribution. For wet material, allow drying time with occasional turning, or consider adding dry material to balance moisture content.
Always maintain OMC (Optimal Moisture Content) for best compaction results
Avoid GSB laying during heavy rain to prevent material washout
Compacting in thinner layers (max 150mm) achieves better density than single thick layer
Start compaction from edges and move toward center for uniform density
Install reference pegs at 10m intervals for better thickness and level control
Store GSB material on elevated platforms during monsoon season
Plan material deliveries to match daily laying capacity to avoid stockpiling
Maintain consistent roller speed (2-4 km/hr) for effective compaction
By following this Standard Operating Procedure, GSB road construction can be executed efficiently, ensuring stability, durability, and compliance with IS standards. Proper execution and strict adherence to safety measures will result in strong, stable, and durable road foundations. The GSB layer provides essential support for subsequent pavement layers and contributes significantly to the overall performance and longevity of the road structure. Regular quality checks and documentation will help maintain high standards throughout the construction process, resulting in roads that provide reliable service throughout the project's operational life.