Q: We'd like to have a gravel driveway, but we also need to be able to plow it in the winter. Is that possible? —roland boucher, Weston, Mass.
Roger Cook replies: Sure, if you use a paving technique called chip sealing. Basically, it's just a layer of washed stone embedded in a tar-like substance sprayed over asphalt. (It won't work on concrete.) But when the paving crew is finished, usually in a couple of hours, you have what looks like an upscale, all-gravel driveway without gravel's maintenance headaches: There's no raking stones out of the yard or adding new ones every year. And when it snows, the surface can be cleared with care using a plow or a snowblower, just like regular pavement.
This job must be done in dry weather—after the ground gets above 50 degrees F and before the leaves fall—by a paving pro with experience handling the hot tar, heavy machines, and tons of stone that chip sealing requires. Here's what to expect when a crew shows up at your house.
Note: Not a DIY project. Requires a paving crew of eight, heavy machinery, and specialized equipment for heating and applying bitumen.
Apply the Bitumen
Before the crew arrives, remove any weeds or moss and sweep the driveway clean with a broom. Hot tar can't stick to wet pavement, so the paving contractor will schedule the work for a dry day. The crew starts the process by using a long wand to apply an even, ¼-inch coat of MC3000 bitumen heated to 190 degrees F.
Dump the Stone
As soon as the bitumen is down, the wheelbarrow crew hauls dry stone from a dump truck and unloads it onto the hot tar. The material used for this project—tan peastone—is a popular choice. Other colors and types, including crushed stone, can also be used, as long as the stone is washed and screened to ⅜ inch or less.
Spread the Stone
Following right behind the wheel-barrows, crew members with wooden lutes spread the stone over the tar, making an even layer about a half inch thick. This step must be done quickly, before the tar cools. Stones that fall outside the driveway's edge should be raked or swept back.
Roll the Surface
Once the stones are spread, a multi-tire pneumatic roller machine is driven back and forth over the stones to press them firmly into the bitumen. (A pavement roller with a steel wheel would crush the stones.) When the rolling is done, the driveway is ready for use.