Quality control in urban road construction

Quality

Quality is the degree to which a set of inherent characteristics of a product or service meets the requirements: the specified standards, the client's needs and fitness for use. In construction, quality means the work follows the drawings, specifications and codes and is safe, durable and functional.

Quality control in urban road construction

Quality control checks every stage of the road work against the specification (for example the Standard Specification for Road and Bridge Works of the Department of Roads, Nepal) using inspection and tests.

 Wearing course  (bituminous)
 Binder / base course
 Sub-base (granular)
 Subgrade (compacted)

1. Survey and setting out: check alignment, levels, width and camber before work.
2. Subgrade: test soil (CBR, Proctor density); compact to the required density and check by field density (sand replacement) test.
3. Sub-base and base: test aggregate gradation, Los Angeles abrasion value and plasticity; check layer thickness, moisture and compaction.
4. Drainage and utilities: make drains, culverts and utility ducts first, so that the road is not cut after paving.
5. Bituminous work: check bitumen grade and content, aggregate quality, mix temperature, and laying and rolling; do Marshall test and core density.
6. Concrete work (kerb, footpath, rigid pavement): control mix, slump, cubes and curing.
7. Finish: check surface regularity with straight edge, levels, cross fall and thickness.
8. Traffic and safety management during construction to protect workers and the public.
9. Documentation: daily records, test results, inspection and approval before the next layer; corrective action for failed tests.
10. Supervision by trained engineers, regular audits and final inspection before handing over.