Asphalt paving in Ottawa, laid to the Ontario spec

Why we will move your date rather than pave cold

OPSS 310, the Ontario Provincial Standard Specification for hot mix asphalt, is explicit. A binder course may not be placed unless the air temperature at the road surface is at least 2 C and rising. A surface course needs at least 7 C and rising. Specialty surface mixes need 12 C. Paving is not permitted if the roadbed is frozen, the surface underneath has to be dry at the time of placement, and spreading and compacting must be finished by half an hour after sunset. Those are not our rules and they are not a scheduling preference. A crew paving a driveway on a 4 C November afternoon is working below the provincial standard, and the mat they leave behind will not have been compacted properly. If the weather turns on your booked date, we move the date.

The base is where the money should go

Ottawa’s light duty pavement standard is 50 mm of HL-3 or Superpave 12.5 over 150 mm of Granular A and 300 mm of Granular B Type II, compacted to at least 98 percent Standard Proctor maximum dry density. The heavy duty section adds a 50 mm binder course and deepens the Granular B to 450 mm. An independent geotechnical report reviewed by the City for Riverside South recommended 90 mm of asphalt over 150 mm of Granular A and 375 mm of Granular B for local roads carrying no truck traffic. A driveway carries far less load than a road and does not need a road’s full structure, but the granular layer is doing the same job in both cases, and that job is mostly drainage. Frost damage requires a frost susceptible soil, freezing temperatures and available water at the same time. Here the first two are fixed, and a clean, well graded, properly compacted base is how the third one gets controlled.

Where an asphalt paving job is won or lost

Laying asphalt is the most visible step in a paving job and the least decisive one. Two crews can lay identical mix on the same day and produce driveways that diverge completely within three winters, because everything that determines longevity happened before the truck arrived or during the twenty minutes the mix stayed workable.

Hot mix asphalt is compacted, not simply poured. Rolling squeezes air out of the mat and locks the aggregate into a dense interlocking structure, and that only works while the material is hot enough to move. A 40 to 50 mm residential mat on cool ground loses heat from below and above at once, so the crew has minutes rather than the hour a highway lift allows. Miss that window and the mat sets with air voids running through it. Water enters, freezes and expands, the surface ravels, and a compaction failure in year one presents as potholes in year four.

Binder and mix grades for asphalt paving in this climate

The asphalt cement grade in Ottawa's civil servicing standards is PG 58-34. Performance graded binders are specified by the temperature range they have to survive, and the minus 34 is the low end. Ottawa's record low is minus 36.1 C, so the material specified for this city is engineered within two degrees of the worst night it has ever had.

On mix design, Ontario uses HL-3, HL-4 and HL-8 alongside the Superpave designations 4.75, 9.5, 12.5, 19.0, 25.0 and 37.5, plus stone mastic asphalt for premium surfaces. For residential driveways, HL-3 or Superpave 12.5 is the normal surface course. Naming it on a quote costs nothing and tells you the contractor is specifying rather than ordering whatever the plant has going.

Any workmanship warranty is set out in your written quote, job by job. Call (343) 314-8525.