For hairline cracks, it is not uncommon to see a few develop in a slab over time. Some may even occur during the concrete curing process if the concrete is too wet, dries too quickly, or is exposed to significant extremes in temperature.
Hairline cracks may develop in concrete foundations as the concrete cures. Hairline cracks do not cause problems with the stability of the foundation but do cause leakage problems. If the cracks appear shortly after pouring the concrete foundation, concrete may have been mixed poorly or poured too quickly.
A well-made concrete structure should not develop structural cracks quickly. Nevertheless, hairline cracks can be expected. Don't stress; these cracks are not a sign of bad quality and can be fixed without much effort.
Plastic shrinkage cracks are typically very narrow in width and barely visible. While nearly invisible, it is important to remember that plastic shrinkage cracks don't just exist on the surface, they extend throughout the entire thickness of the slab.
Cracks of greater width than 0.3 mm may present structural durability issues. If a crack on a concrete floor or slab widens sufficient to present a tripping hazard, it is considered serious and requiring repair.
Hairline cracks can grow over time and weaken the structure, such as in a home foundation. Some hairline cracks can also cause leaks in a foundation. It's important to watch the cracks to see if they grow. Contact a concrete contractor if you notice cracks exceeding 0.3 millimeter wide.
In applications such as concrete slabs and residential foundation walls, cracking is inevitable and expected. As the surface of concrete dries, water evaporates from the spaces between particles. As this water dissipates, the particles move closer together, resulting in shrinkage of the concrete.
Ask any contractor if they can guarantee that the concrete patio they pour won't crack, and they will all give you the very same answer: No. This is because concrete will crack; no matter what anybody does, there is just no avoiding the fact that concrete cracks.
In residential concrete, 4 inches is the minimum thickness for walkways and patios. Garage slabs and driveways should be 5 to 6 inches thick if any heavy truck traffic is anticipated, otherwise 4 inches is adequate.
Foundation cracks are, for obvious reasons, one of the number one signs of foundation failure. However, not all foundation cracks are created the same, which means they won't all require the same repair method—some may not require repair at all.
Hairline cracks of less than one millimetre in width or slight cracks of between one and five millimetres are generally not a cause for concern. If you begin to notice these, they can generally be filled and painted over as they're a crack in the plaster but not in the wall itself.
Cracks up to ¼ inch in width can be filled with sealant.
Like spider web cracks, these small cracks do not indicate a larger problem, and they often show up soon after the concrete is poured.
As the concrete hardens, which is caused by the cement and water forming bonds, some of that water escapes through evaporation. This reduces the size of the concrete slab, and since concrete is a very hard, tightly bound substance, this loss of material creates stress. This stress can lead to cracks in the concrete.
Here's how to know if a crack is structural: One of the easiest 'tells' for structural damage cracks is that they grow over time. A thin, non-structural crack can quickly become a structural foundation crack if it gets wider after several weeks or months.
The 28-day curing time is a common requirement, but don't expect all cracking to be completed by 28 days. Drying shrinkage cracking can take place months after a concrete slab is placed.
The higher the PSI the more durable your concrete will be and will thus be resilient to cracking. The average residential project uses a minimum of 2,500 to 3,000 PSI; however if you're concerned about cracking then we recommend talking to your concrete contractor about stronger products on the market.
To avoid water seepage and further damage, it's critical to seal any cracks that develop. This article will discuss why cracks happen and how to quickly repair them.
Prevent excess water.
High water content in a concrete mix design is one of the primary causes of differential volume changes that cause high shrinkage and excessive cracking. The use of chemical admixtures, such as water reducers, creates easy-to-place, high slump concrete, without adding excess water.
Quikrete 50 lb. Crack-Resistant Concrete is designed to significantly reduce the amount of cracking caused by drying shrinkage. This concrete is ideal for driveways, walkways, floors, sidewalks and patios.
The hardening, or curing, continues as long as moisture remains in the concrete. If too much water is lost from the concrete through evaporation, the hardening process slows down or ceases.
How to fix hairline cracks. If you have hairline cracks in your walls you simply need to mix up a suitable filler such as patching plaster or buy a small tub of ready mixed such as Everbuild All Purpose Ready Mixed Filler and apply.
But at the same time it is relatively weak and brittle when formed into thin sections. So any movement at all in a large slab will create cracks like the ones you're seeing in your driveway. Concrete cracking can show up at any time, even on a one year old slab like yours.
0 - Hairline cracks less than 0.1mm.
Hairline cracks are classed as negligible.
Concrete caulk or filler is best for cracks no wider than 1/2 inch. This thick material is injected into the crack with a caulk gun or by directly squeezing it out of the tube. You can use concrete caulk on both vertical or horizontal cracks. Our top pick is Sikaflex Pro Select Self-Leveling Sealant.
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.