Understanding Materials: Asphalt

Hot Mix Asphalt (HMA) is a mixture of Asphalt Cement (a petroleum-based “glue” that comprises less than 8%, by weight, the total pavement mixture) and Aggregates (various sized stones, dust, hard inert materials and sand, comprising approximately 92%, by weight, the remaining pavement mixture.)

Asphalt does not cure in the sense that concrete does, and once spread and rolled, it can be cut or drilled almost immediately. Unlike cured concrete, sand in asphalt never bonds as firmly, and the slurry created when sawing will be extremely abrasive. A bond matrix similar to cutting green concrete and undercutting protection steel cores are important factors when undertaking asphalt cutting operations. Some unique factors should be observed when cutting asphalt:

  • Hard & large sized Aggregates in the asphalt will cause the blade to cut slower
  • The greater the Aggregate-Sand ratio, the faster the blade will cut, but total footage may decrease
  • Total asphalt depth can vary. It is common to cut through the asphalt layer into the sub-base. Generally, the sub-base contains a high content of very abrasive materials such as sand, dirt, dusts and like materials. This undesirable situation causes rapid wear of the diamond blade
  • Chunks or broken-up asphalt to be cut often attract dirt and sand fillers within the cracks. This, too, will make the asphalt more abrasive and affect the life of the diamond blade