In theory, concrete that is formulated correctly for its use and placed on a well compacted, well engineered base, and finished perfectly, should never crack. But that rarely happens. So concrete usually cracks. That fact is the reason concrete contractors put "control" joints in large slabs of the material.
Concrete driveways can crack for many reasons. Repeated freezing and thawing, heavy loads, tree roots and even shifts in the ground can cause damage. When you learn how to repair cracks in a concrete driveway, you may be able to stop them before they lead to bigger problems.
Cracks in concrete are common and they develop when stresses in the concrete exceed its strength. Cracks are often caused by normal shrinkage of the concrete when hardening and drying.
Start curing the concrete as quickly as possible.
A longer curing period than is generally required for compressive strength may be needed in cold weather to reduce cracking. Apply a curing compound or protect it with damp burlap or other covering for at least three days.
The majority of cracks occur within 2-3 days after concrete has been placed. These are preventive measures which will minimise cracking in that period: See that sub-grade is well-compacted.
Concrete of a thickness of less than 5″ is more prone to cracking, unfortunately this includes nearly all the poured slabs out there. Slabs 4″ thick are twice as resistant to fractures (heavy loads from above as well as lifting from below) than are 3″ slabs.
Yes, in about a month, hairline cracks should subside. While shrinkage cracks can show up on the surface within hours of having concrete poured, it takes a full monthfor new concrete to fully settle. Don't be surprised if cracks that seemed visible at first are nearly impossible to see after a month of settling.
The best way to prevent your driveway from cracking is to apply sealant. Even though it may seem like a no-brainer, a lot of homeowners don't do it and then have to deal with concrete issues down the road.
Prevent cracks
For driveways, prevention means sealing concrete annually and sealing asphalt every few years to prevent water from penetrating, freezing and cracking. Tree and shrub roots can cause cracks by pushing up from underneath. The solution is to remove trees near drives or have their roots trimmed away.
Evaluating Concrete Crack Severity
Cracks smaller than 0.3 mm in width are generally not serious and of not structural impact. However, they should be monitored for any growth. Cracks of greater width than 0.3 mm may present structural durability issues.
While plastic shrinkage cracks can happen anywhere in a slab or wall, they almost always happen at reentrant corners (corners that point into the slab) or with circular objects in the middle of a slab (pipes, plumbing fixtures, drains, and manholes).
As the concrete is curing, excess water is evaporating, and the volume of the concrete in your driveway shrinks. This causes it to pull apart from itself, and that is why you see the small cracks develop shortly after pouring.
Probably the single most common reason for early cracks in concrete is plastic shrinkage. When the concrete is still in its plastic state (before hardening), it is full of water. This water takes up space and makes the slab a certain size. As the slab loses moisture while curing it gets a bit smaller.
Hairline cracks are commonly observed in freshly placed concrete and their occurrence is owed to the phenomenon of plastic shrinkage. As the name implies, these cracks are very small- about 0.003 inches (0.08mm) in width and can be very shallow.
For most sidewalks and driveways, the best choice is an acrylic sealer. Acrylics work by forming a clear coating on concrete. The coating is easy to apply with a roller or sprayer and will last two to five years, depending on weather and traffic.
Add a concrete sealant.
As the surface expands, there is the potential for damage like cracks and divots. You can help prevent this by coating the concrete driveway or patio with a waterproof sealant. This will keep water from entering, and prevent expansion during high temperatures.
Can Sealing Prevent Cracks on Concrete Surfaces? Concrete sealing can stop most types of concrete fractures. This fact is especially true if the crack is a result of poor-quality work in the concrete mix or site preparation. However, sealing can prevent future damage that may start from the top layer of the concrete.
Concrete cracking can show up at any time, even on a one year old slab like yours. It is possible the base under your driveway wasn't compacted correctly, and that may have caused the concrete to sink or settle slightly, and thus to crack.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
Effects of too much mixing water
Segregation of the concrete mix under certain conditions resulting in variable quality throughout the concrete mass. Cracking - with too much water, there will be lower tensile strength, and a tendency towards high shrinkage and subsequent cracking.
Shrinkage: The most common type of cracking in concrete, especially early on, is shrinkage. Concrete is a mix of cement and water. As the concrete hardens, which is caused by the cement and water forming bonds, some of that water escapes through evaporation.
Rebar, or reinforcing bar, is a common feature of many concrete applications. Its primary purpose is to increase the tensile strength of the concrete, helping it resist cracking and breaking. With greater tensile strength, concrete is better able to resist breaking under tension.
Driveway Cracks: Yes, driveway cracks can indicate you have foundation problems. In fact, it is the first on the list. A driveway is typically poured so that the water will flow away from the foundation.
Yes. Every driveway should be sealed with a high-performing sealer. A sealer will protect your driveway from the following: Abrasions.
For the most part, if the cracks are less than 1.5mm in width and the length is less than those specified in Australian Standards (generally ranging from 5mm to 15mm) then it can be assumed to be minor cracking that is acceptable.