New asphalt requires up to six months to fully harden and cure. In that time, you can still use the driveway, though it will soften and harden as the temperature fluctuates. When the temperature is high, the asphalt will become more pliable and will scar easily if you drive over it. Watering the new asphalt is a way to harden the asphalt again in hot weather so it is usable.
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Move all your vehicles off the asphalt driveway. Drive them slowly, and do not turn the wheel too sharply to avoid scarring the asphalt.
Stand at the top of the new driveway with a garden hose. Turn the garden hose on low pressure.
Water the driveway with the garden hose from the top of the driveway to the bottom. The water may produce suds as the chlorine in the tap water reacts to the diesel in the asphalt. Continue watering until the asphalt hardens.