How to Patch a Hole in Blacktop

This cracked area in the blacktop will soon be a pothole. You can make a permanent repair using skills and magic. Photo Credit: Tim Carter

DEAR TIM: There are several places in my asphalt / blacktop driveway that are starting to crack. It looks like holes and entire sections of the blacktop will fail. I can't afford to have a professional come in to repair the drive. In the past the patches I've installed have all failed and popped out. Is there a way to patch my driveway and have the repairs last for many years? What did I do wrong? Amy S. Goochland, VA

DEAR AMY: Potholes in driveways and roadways are the bane of homeowners, drivers and road maintenance workers. They appear like mushrooms after a spring rain, often with little warning. Unfortunately many potholes re-appear again, like yours, because the repair process was done poorly or skipped one or two very important steps.

It's possible to repair your driveway yourself, but realize it may take some extra effort on your part to get long-lasting results. You can make quick work of the job if you have access to a special power tool that you can rent at a tool rental center.

Why do most asphalt hole repairs fail?

Most blacktop or asphalt hole repairs fail because of two reasons. The shape of the hole is wrong and the base material under the blacktop is either fouled or not compacted. If you desire to patch the hole in your driveway only one time, you must do several things correctly.

In your case, it sounds like you'll have to remove some of the cracked blacktop to make the repair. It's possible your repairs in the past failed if you tried to add patching compound on a shallow depression. That method will never work if you're using the ready-mixed asphalt repair products that come in a bag.

Do what the Dentist does!

Think about how fillings in teeth work. Your dentist drills into your tooth and creates a hole where the bottom of the hole is slightly larger than the top. He adds a filling compound that gets hard quite quickly. Because of the shape of the hole, the filling is locked in place. You need to do the same thing with your pothole.

What to do at the edges of the cracked area?

I'd use a power demolition hammer with a 1.5-inch-wide flat chisel at the end to excavate the failing blacktop in the center of the cracked area. When you're at the edges of the cracked area be sure you lean the top of the power hammer in towards the center of the hole. This will create an angled face on the edges of the blacktop. Remove all loose pieces of blacktop from the hole so the gravel base is exposed.

Make sure the crushed gravel under the blacktop is free of any mud or soil. If there is mud in it, removed the fouled gravel and replace it with crushed gravel that matches what was originally under the blacktop. Compact it well with a tamping tool or a flat piece of wood you hit with a hammer. You can add a small amount of water to the gravel to help compact it.

Read the instructions on the bag of blacktop repair material. They will tell you the minimum and maximum thickness of the repair patch. Usually you can safely add 3 inches of patch material, but you must do it in several stages. You add 1 inch of material to the hole and then compact it.

Your final layer of patching material needs to be slightly less than one-half inch above the surrounding existing blacktop. Using a heavy metal tamper you want to pound the repair material so it's flush with the surrounding blacktop. Be sure there's no shallow depression that will cause a puddle to form after a rain.

If the repair is in a spot where car or truck tires contact it, I'd recommend you place a piece of scrap plywood over the repair area until it cures and gets hard. The repair compounds that come in a bag will get very hard over time, but when first installed they're soft.

Anytime no car traffic is expected on the patch, remove the plywood to allow air to get to the repair compound. Exposing the patch to air and sunlight will accelerate the curing process.

You can watch my video that shows how to patch blacktop. Simply type "driveway repair video" into the search engine at www.AsktheBuilder.com.

This column was featured as the I Didn't Know That! column in the July 23, 2013 AsktheBuilder Newsletter.

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