January 5, 2012

Late season paving is an avoidable reality for road construction

DAN O’REILLY

correspondent

Late season paving is going to occur in road construction despite precautions which should be taken to avoid it, members of the Ontario Hot Mix Producers Association (OHMPA) were told at the association’s recent annual conference.

Contractors and the municipal officials who award their contracts should work to avoid late season paving, if possible, said the association’s technical director, Sandy Brown.

In the cool weather of late fall paving asphalt cools faster and it’s more difficult to achieve compaction and good joints, he warned.

Municipalities should issue critical contracts early in the year to allow them to be completed in favourable weather, as well as calling for night work early in the season when there is also better weather.

Some of the steps contractors can take include prioritizing scheduling, completing the mix designs and obtaining approvals well in advance of the construction start, plus having sufficient manpower and serviceable equipment available, said Brown.

But he acknowledged late season paving is going to happen because of factors such as late tender calls, unrealistic schedules, and unforeseen utility removals. “Plan for it… it’s not like it’s a surprise.”

When dealing with late season paving municipalities need to have experienced contractors on site to deal quickly and constructively with issues as they arise. Officials should also be wary of predicting weather patterns, especially after Thanksgiving.

“Don’t try to be a meteorologist, sometimes you have to allow paving in borderline conditions on work that can’t be postponed but if you do, accept that performance may be compromised.”

Some of the design strategies that may assist late season work include: finer mixes which are easier to place and obtain compaction; thicker lifts which keep asphalt heat longer with the result it is easier to place; echelon paving; and using warm mix asphalt which loses heat slower than hot mix.

For their part contractors can put into action several protective measures such as placing tarps on hot mix asphalt delivery trucks to keep the heat in or using insulated truck boxes.

Other precautions include using material transfer vehicles to store and distribute mix to the pavers, which should also be equipped with preheated screeds.

In the end, however, those safeguards may not be enough and the project may have to be rescheduled to spring if quality of the pavement is going to be jeopardized, said Brown.

In those cases “somebody has to stand up to the plate and say I think we’re finished for the year.”

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