Modified Special Provision of using HMA compaction core to measure pavement’s lift thickness for QA acceptance in selected MTO paving contracts

According to the current sampling and testing requirements in OPSS 313, a pavement core with 50 mm diameter is obtained from the pavement after paving to measure the HMA lift thickness for QA acceptance. Another core (compaction core) with 150 mm diameter is taken to measure the compaction density. However, excessive coring on a newly paved road will compromise its structural capacity and surface appearance and increase the workload of the construction crew.

In order to reduce the number of cores required for QA acceptance, a modified standard provision is developed and specifies using the compaction core for both the pavement’s compaction density and lift thickness measurements as the method for QA acceptance, and the requirement for taking the pavement core for lift thickness measurement can be eliminated.

To accommodate this modified sampling and acceptance method, the referee processes for pavement compaction density and lift thickness will be altered accordingly. The lot system and payment adjustment calculation for thickness acceptance will also be adjusted. This modified standard provision will apply on selective MTO paving contracts as pilot projects to evaluate the efficiency and effectiveness of using this modified QA sampling and acceptance method on MTO’s paving contracts.