City of Regina - Asphalt Rut Susceptibility Testing Results

The City of Regina is planning to implement new asphalt specifications for the 2018 construction season. One of the proposed changes is to include a requirement for rut susceptibility testing of the asphalt mixes used on arterials, industrials and bus routes in the core area. Asphalt mixes used on residential and collector streets would not require rut susceptibility testing.

Rut susceptibility testing is completed using an Asphalt Pavement Analyzer (APA). The APA uses an aluminum wheel that is loaded onto a pressurized linear hose and tracked back and forth over the asphalt pavement sample. The depth of rutting is measured after the wheel has been tracked for a set number of cycles at a constant load and hose pressure. The proposed new specifications would allow no more than 5 mm of rutting depth after 8,000 cycles.

The City of Regina committed to completing rut testing on samples of asphalt obtained from local suppliers used on City projects over the summer. Therefore, samples were obtained from two local suppliers and sent to the National Center for Asphalt Technology (NCAT) at Auburn University for rut susceptibility testing.

One local supplier provided a standard City of Regina, 50 blow Marshall, 16 mm mix while a second supplier provided a 75 blow Marshall, 16 mm mix typically used on Ministry of Highways projects.

The results of the rut testing are as follows:

Type of Mix Average Rut Depth (mm) as reported by NCAT
Standard City of Regina, 50 blow Marshall, 16 mm aggregrate 4.9 mm
Ministry of Highways, 75 blow Marshall, 16 mm aggregrate 7.1 mm






The results indicate that a 75 blow Marshall Asphalt mix does not necessarily guarantee rut resistance.

If you have any concerns or require any additional information, please contact Bill Wright at, phone 306-570-1562.

December 4, 2017

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