When can an Ottawa concrete driveway take a car?

A new concrete driveway in Ottawa can typically support a passenger vehicle after 7 days of curing, but the full 28-day cure period is strongly recommended before allowing heavy vehicles or regular traffic.

Concrete gains strength progressively through a chemical process called hydration. At 7 days, a properly mixed 30 MPa air-entrained concrete mix (the minimum specification for Ottawa driveways) will have reached roughly 70 percent of its design strength — enough to support a standard passenger car without permanent damage. By 28 days, it reaches full design strength and can handle regular vehicle traffic, SUVs, and light trucks without concern.

The practical guidance most Ottawa contractors give is this: walk on it after 24 to 48 hours, park a car after 7 days, and treat it normally after 28 days. If your contractor poured in warm summer conditions (above 25 degrees Celsius) with good moisture retention during curing, you may be on the faster end of that window. If the pour happened in cooler fall weather — say, September in Ottawa when overnight temperatures start dropping toward 10 degrees Celsius — hydration slows significantly and you should lean toward the full 28-day wait before driving on it.

Ottawa's Climate Makes Curing More Complicated

Ottawa's temperature swings directly affect how concrete cures. Hydration essentially stops below 5 degrees Celsius, which means any concrete poured in late September or October needs to be protected with insulating blankets to maintain adequate curing temperatures. If your driveway was poured in cool conditions, do not assume the 7-day rule applies — ask your contractor specifically what curing protection was used and whether the timeline needs to be extended.

Hot weather creates the opposite problem. In July and August, Ottawa's heat and low humidity can cause the surface to dry too quickly, leading to plastic shrinkage cracks before the concrete has properly set. Reputable contractors will apply a curing compound or wet-cure with burlap and poly sheeting to slow moisture loss. If your contractor did not take any curing precautions during a hot pour, the surface may be weaker than expected and worth waiting the full 28 days before driving on it.

The First Winter Is Critical

Regardless of when you start driving on it, do not apply any deicing chemicals to new concrete during its first winter. This is one of the most damaging mistakes Ottawa homeowners make. Rock salt, calcium chloride, and magnesium chloride all cause surface scaling (spalling) on concrete that has not yet achieved full carbonation and surface hardness. The result is a pitted, flaking surface that is both unsightly and structurally compromised. Use sand for traction during that first winter season — it is less convenient but it protects a significant investment.

Also avoid letting heavy vehicles (moving trucks, delivery trucks, concrete mixers) onto the driveway for at least 28 days, and ideally longer. A passenger car at 1,500 to 2,000 kg is well within the design load of cured residential concrete. A loaded moving truck at 10,000 to 15,000 kg is not, and can crack even a fully cured residential slab if it tracks over an edge or a control joint.

If you are planning a new concrete driveway, Ottawa Driveways can match you with local concrete contractors for free estimates. Browse paving and concrete professionals through the Ottawa Construction Network at justynrookcontracting.com.