Asphalt core cutting is a quality control technique used to verify the thickness of the asphalt pavement and determine the in-place density of the compacted asphalt. The extracted core sample can also be used to verify the asphalt binder content through laboratory testing and confirm whether the aggregate gradation complies with the approved mix design.
Core cutting is normally carried out using a 100 mm diameter diamond core cutter. The cutting depth should extend through the entire asphalt layer and slightly into the base course to ensure a complete core sample is collected. The number and location of cores are determined by the project specification or the engineer's instruction. To obtain representative results, core locations are often alternated between the center, left, and right side of the pavement.
During cutting, a continuous supply of water should be provided to cool the diamond bit, reduce dust, and produce a smooth cut. After extraction, each core is carefully packed in a bag and labelled with the chainage, lane, and side of the road before being sent to the laboratory for testing.
Core cutting also plays an important role in the Interim Payment Certificate (IPC). Thickness is one of the major acceptance criteria. If the measured thickness is significantly less than the specified value, the contractor may be required to remove and replace the asphalt. For small variations that fall within the project specification, the engineer may accept the work, but payment may be adjusted based on the measured average thickness for that section.
Although asphalt paving crews continuously monitor the laying thickness during construction, core cutting remains one of the most reliable quality control methods for verifying the actual thickness, density, asphalt binder content, and compliance of the completed pavement.
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