Have you noticed that your asphalt or concrete driveway is beginning to sag? While a driveway typically has a lifespan of up to 30 years, it can begin to fail as the years go by. “Concrete is a very strong, durable material,” explains Jim Wiederaenders, a senior design technician. “However, for all its strength and usefulness, concrete has a finite lifespan.” Both concrete and asphalt driveways can be damaged from soil erosion, expanding clay soils, drainage problems, or foundation issues.
A sinking driveway could be a sign of a serious problem caused by the underlying soil. Foundation issues usually show up first as sinkholes or depressions in the asphalt, giving the driveway a bumpy surface. Under a concrete driveway, you’ll first notice cracks that begin to separate. Some sections of your driveway can sink, while other sections seem stable. But any sinking or depressions should be addressed.
What causes a driveway to begin sinking? Typically, it comes down to installation, soil, drainage, or damage. During installation of your driveway, there could have been some issues that will only show up later. These include improperly compacted soil, too little gravel used as a base layer, or an incorrect mix of asphalt and aggregate.
Some areas of the country have soil that is rich in clay. During winter, the clay will freeze and expand. When it shrinks during hot weather, it leaves pockets that can fill with water. During heavy rains or frequent watering, the soil can wash out from underneath the driveway. The driveway will then sink into those areas.
Water can pool on your driveway if there is a drainage problem. You could also have erosion along the sides of the driveway. Any dirt that gets washed out from under your driveway will eventually lead to sinking issues. Some sunken driveways result from an unnoticed water leak or from a broken water pipe or sewer leak. In these cases, repair to the leak must be made before fixing your sunken driveway.
If your driveway is beginning to sink, it can show up as an unlevel slab or as a pothole. Driveway issues get worse over time. If you have areas of your driveway that break off, have extensive cracking, or if you notice asphalt wash-off, then you could see a rapid increase in sinking.
Fixing a sunken driveway isn’t just a cosmetic issue. When a driveway sinks, it can cause water to be redirected toward your home’s foundation instead of away from your home. This water can destabilize your foundation or even cause water seepage into a basement.
And there is the question of safety. A sunken driveway is unsightly, but it is also dangerous. The uneven surface of a sunken driveway is a tripping hazard for anyone walking on it, especially during rainy or snowy weather. You could be liable for injury to a visitor if you have an unsafe driveway.
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Mudjacking, or slabjacking is a procedure that forces wet concrete under the existing concrete slabs of your driveway. This raises up the sunken area and levels it. Originally, the substance used was mud, hence the name. Now, rock and cement are added for more durability. Mudjacking uses a slurry of cement, topsoil, and water in a mixture that is liquid enough to flow through a large hose.
As the slurry is pumped in, it lifts the driveway and fills in any voids or pockets of space under the concrete surface. When dried, it offers solid support for your driveway. However, if the drainage issues that led to your driveway sinking are not addressed, you could see a return of the problem.
Mudjacking is cheaper than removing and replacing your entire driveway slab. It is also durable, able to withstand vehicles and moderate vertical compression. One drawback to mudjacking is that the installation process requires the drilling of fairly large holes in your driveway. These holes, usually at least two-inches in diameter, allow for the insertion of the hose nozzle. These holes are patched, but will still be visible after your driveway work is complete.
As with mudjacking, using expanding foam to support and lift your driveway is cheaper than a full replacement. In a process sometimes called polyjacking, concrete slabs can be lifted and leveled using a polyurethan foam. This high-density, lightweight foam is injected under the slab and expands.
The foam forms a closed cell polymer. Unlike an open-cell foam, such as a sponge, this closed-cell foam has pockets of gas, filling the space and acting as a waterproof barrier. Instead of the larger hole used for mudjacking, the hole for foam injection is typically less than an inch in diameter.
While mudjacking will fill in most spaces under the concrete slab, ploy-foam does not expand into every void. Its waterproof properties make it very durable over time, but the surrounding dirt could experience some erosion if there are drainage problems. Polyurethan foam injection is excellent when used for precision leveling and on smaller driveways that are not experiencing ongoing drainage or erosion issues.
Concrete resurfacing can work to repair a sinking driveway if there is only a slight displacement or if the sinking is localized. Resurfacing puts down a thin layer of concrete. First, the driveway is power washed. Then small cracks and holes are filled with an epoxy mortar. Finally, the surface is covered by pouring new concrete in a thin topping layer. A resurfaced driveway can be used as soon as 48 hours after applying the resurfacing material. This process not only can relevel your driveway and fill in cracks. It also restores the surface of your driveway, making it look like new.
A drawback to resurfacing is that it won’t address any of the causes of the sinking, such as drainage or soil issues. You could end up with problems returning. At a minimum, if no other mitigation steps are taken, you can expect that some of the original cracks in your driveway will return eventually.
If your driveway has extensive areas of sinking, you need to consider replacing your driveway completely. Of course, this option is the most expensive, typically three to four times as costly as either mudjacking or foam injection.
Since the majority of sunken driveway issues result from drainage, erosion, or soil movement, you should be aware of any problems you may have. There are some steps you can take to reduce the effects of erosion and to protect your concrete or asphalt driveway from sinking.
· Ensure good drainage on your property and keep water off your driveway. Make sure your downspouts are clear of debris and position them correctly so they drain water away from your foundation and driveway. Downspouts should discharge rainwater at least five feet away from any concrete slab.
· If the soil along the edges of your driveway washes away, you may eventually see some pockets open up along the edges of the driveway. These should be addressed as soon as possible. Pack soil into the open spaces and along the edge of the driveway. Check to make sure that water is not running under the slab.
· Seal all cracks and joints in your cement driveway with a polyurethan or silicone caulk. Cracks in a driveway allow water to seep under the slab. During winter, this water can freeze and expand. When warmer weather returns, this ice will melt, often leaving gaps in the soil. To prevent these from causing sunken spots, keep the water out by sealing up the cracks.
· Don’t use salt or other de-icing chemicals on your driveway. These can degrade the surface and lead to cracks. Use a snowblower or a snow shovel with a plastic edge instead of tossing melting chemicals on your driveway.
· Keep your driveway clean to extend its life. Automotive fluids can seep down a quarter of an inch or more. This stains concrete and softens asphalt. If you have a motor oil spill, spread some non-clumping kitty litter onto the area. Sweep it up and then wash the spot with a grease-cutting dishwashing detergent mixed with warm water.
· Don’t overload your driveway. Typical driveways are not able to handle heavy loaded vehicles for long periods of time.
· If you have nearby shrubs or trees along the edges of your driveway, consider removing them to prevent cracks or sinking. Roots can get under a driveway, causing parts of it to lift and other parts to sag.
Whether you can do a DIY sunken driveway repair or you have to call in a professional depends on several factors. The most important consideration is the extent of the work. If you are trying to fix a few low spots, you may be able to complete the work yourself.
Some conditions, however, will need the help of a professional. If your concrete slab has to be lifted, then you will not have the proper equipment to get the job done. Resurfacing an asphalt driveway is also best left to the professionals.
If your driveway is sinking due to drainage, soil, or foundation issues, consider getting advice from a professional soil engineer or landscaper. While you can get your driveway repaired quite easily, if you don’t address the underlying problems, you may end up with more sinking in the years to come. Identifying the issues and correcting them will eliminate more problems down the road.
If you're ever in need of a waste bin, Discount Dumpster has you covered. We offer a wide variety of dumpster sizes for any type of project. In the case of repairing a sunken driveway, we offer 10 and 15 yard dumpsters. These sizes are ideal small residential projects like driveway repair.
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