Road Base & Subbase Works
NLS Contractors builds road base and subbase layers in Riyadh, Jeddah, Dammam, Khobar and across the Kingdom: subgrade preparation, subbase, aggregate base course and compaction. Layers are tested to modified Proctor ASTM D1557 and CBR ASTM D1883, and handover includes survey levels, test records per layer and as-builts.
The asphalt is the visible part of a road, but the pavement lives or fails in the layers under it. The package covers subgrade preparation, subbase, aggregate base course and compaction, built in lifts from the formation up to the underside of the asphalt, with each layer approved before the next one starts.
Thickness, material class and gradation limits come from the pavement design and the owning authority's specification, not from the contractor. National roads follow the Roads General Authority, city streets follow the municipality, and private compounds follow the consultant's specification. The enquiry should say which applies, because the material class and the test frequency differ between them.
The subgrade comes first. The formation is cleared, shaped to the design levels, proof rolled and compacted, and soft areas found at proof rolling are removed and replaced as the engineer directs. Subbase and aggregate base are then placed in lifts, watered to the right moisture for compaction, graded and rolled, with the surface tolerance checked before the next lift.
Tests decide acceptance. Modified Proctor (ASTM D1557) gives the maximum dry density and optimum moisture for each material source. CBR (ASTM D1883) confirms the bearing strength of the subgrade and the subbase material. Gradation is checked on the aggregate, and field density tests confirm the compaction achieved in every layer at the frequency the specification sets. Survey levels are taken after each layer, so the thickness is known before paving starts.
Three inputs move the price: where the aggregate comes from and how far it is hauled, where the water for compaction comes from on an arid site, and how much of the formation needs replacing. The offer states these assumptions. Send the pavement design and cross-sections, the specification, the BOQ with quantities, the geotechnical report, the site city and the programme. Price and lead time depend on the scope.
Specifications
- ✓Layers: subgrade preparation, subbase, aggregate base course and compaction in lifts
- ✓Density: modified Proctor ASTM D1557 with field density tests on every layer
- ✓Strength: CBR ASTM D1883 on subgrade and subbase material
- ✓Design basis: the pavement design and the owning authority's specification
- ✓Checks: aggregate gradation and survey levels after each layer
- ✓Handover: survey levels, test records per layer, as-builts
Frequently Asked Questions
What is CBR and why is it tested?+
California bearing ratio (ASTM D1883) measures the bearing strength of soil and subbase material. The pavement design assumes a minimum value, so the test shows whether the layer can carry the road above it.
Who decides layer thickness?+
The pavement design and the owning authority's specification. The contractor builds to the thickness shown and proves it with survey levels and tests.
Can asphalt start before the base tests are signed?+
No. Each layer is approved with its density and level results before the next one goes on. Paving on an unapproved base is a common cause of early cracking and rutting.
Does the offer include supplying the aggregate?+
The package can include supply and placing of subbase and base aggregate from an approved source, with the haul distance stated. If the client supplies the material, the offer covers placing and compaction.
Who supplies Road Base & Subbase Works in Saudi Arabia?+
NLS Contractors (Northlane Solutions Company) supplies Road Base & Subbase Works across Saudi Arabia, including Riyadh, Jeddah, Dammam and Jubail. Send your specification and quantities to info@nlscontractors.com or info@northlanesolution.com for a quotation.