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Fine-graded Stone Mastic Asphalt – Pavement Rehabilitation of Bloomington Road (York Region Road 40)


Bloomington Road is a two-lane roadway that carries more than 10,000 AADT with approximately 10 % heavy commercial vehicle mostly hauling aggregate to the Greater Toronto Area. Prior to rehabilitation, the pavement was severely oxidized and thermal cracking was extensive. The pavement design included an in-place recycling technique to mitigate reflective cracking and 100 mm of new surfacing HMA. The partial depth recycling process was selected using a rapid curing recycling system to accelerate the build up of cohesion of the recycled material. A heavy duty dense graded HMA was selected as a binder course, while a fine-graded SMA was selected as a thin surfacing course. Both HMA mixes were tested for rutting using a European rut testing device to ensure rut resistance performance. Both mixes were produced using polymer-modified bitumen to mitigate both thermal cracking and permanent deformation. The current concept of Stone Mastic Asphalt (SMA) or “Splittmasticasphalt” was developed in Germany in the mid-sixties and introduced in Canada in 1991. Stone Mastic Asphalt is a gap graded bituminous mixture with a high content of chippings which constitute an interlocking mineral skeleton to resist permanent deformation. The space within the chippings skeleton is filled to a large extent by a mortar rich in bitumen-filler mastic to provide durability. Fine-graded SMAs is a specific category of SMA produced using single-size chippings no greater than 6.7 mm. The resulting mixture provides an aggressive but fine macro-texture conducive to surface drainage and good frictional properties. The rolling noise reduction has been reported to be as much as 3dB(A) compared to dense graded surfacing mixes. This paper presents the Bloomington Rd. project including details related to the roadway characteristics, the pavement design, the material and process selection and the field construction. Finally, the paper provides performance information of the various techniques with an emphasis on the surface characteristics of fine-graded SMA, including skid resistance and noise reduction.

Conference Paper Details

Session title:
Croteau, JM
Hanasoge, N
Construction, Maintenance and operations