Measurement of Asphalt Density Using Microwaves

In a typical paving operation, several parties are involved in producing a quality asphalt pavement (e.g., design mix specifier, hot mix plant operator, QA/QC inspector, asphalt laying operator, and roller compactor operator). However, quite often it is the roller operator’s skill that ultimately determines the density of the compacted asphalt mat and therefore the final quality of the pavement. An under-compacted asphalt mat is permeable to air and water which shortens the pavement life. On the other hand, unnecessary roller passages will lead to over-compaction that is associated with insufficient air void content in the asphalt. An over-compacted pavement is susceptible to permanent deformation [1], leave alone the waste of time and equipment in the compaction process. Hence, it would be highly advantageous if the roller operator is able to continuously monitor the compaction level of asphalt during the paving operation