Case Study: Crack Repair of the Century
Mar 7, 2014
We repaired the Grand Canyon.
All joking aside....
Unsealed control joints and cracks in your concrete can lead to larger problems.
One of the guarantees about a concrete slab is that it will crack. It's just the nature of the product. Concrete typically cracks for a couple of reasons,
• part of the curing process
• stress on the slab
The most common cause of concrete cracking is caused by the concrete slab drying during the curing process. Concrete will crack, guaranteed, when it cures. The cracks are often controlled by what is called control joints. Control joints are put in one of two ways, either cutting them in after the concrete slab is set up, typically the day after the concrete is poured, or with a grooving trowel. This makes a weak spot in the concrete slab, causing it to crack in a straight controlled line rather than randomly along the slab.
Another reason a concrete slab will often crack is when there is stress on it. Stress on the slab can occur a number of ways. One common way it happens is when there is a void under the slab and the concrete slab not strong enough to hold itself. The concrete then cracks and begins to settle. Sometimes the concrete slab cracks because of stress from below. Heavy or saturated soil will heave with the wintertime freezes and then settle in the spring and summer. This movement will often cause it to crack. Other reasons include a lack of reinforcement or inadequate reinforcement in the slab.
So, what can be done about it? First, preventive maintenance, If the concrete slab looks fine, does not have any random cracking or uneven control joints, it's just a matter of time before water penetrating through the control joints cause a settling issue. The control joints should be properly cleaned and sealed to help prevent future problems.
Second, if there is random cracking, uneven control joints, or other offset cracks, determine why the problem has occurred and address it. Uneven joints can often be repaired cost effectively with concrete leveling, sometimes referred to as slabjacking or mudjacking. Once the problem has been taken care of, the random cracking can be ground out, sealed and all the control joints can then be sealed.
While sealing cracks seems like a simple thing to do, and it is, it is also critical that the correct steps be taken to ensure a long lasting seal. Random cracks must be opened up with a v-grinder, dirt must be properly cleaned out, caulk backer must be properly installed, and a high quality caulk must be used. If equal importance is not given to each of these steps the seal may prematurely fail.
Another side benefit to sealing cracks is weeds. Control joints and random cracks provide an excellent environment for weeds to grow. Anyone who has spent time trying to control weeds growing up through cracks in a sidewalk or driveway can attest to how annoying the problem can be. The only other proper way to do it is to get down and pull them by hand.
By sealing cracks several problems are prevented. Water is prevented from getting under the slab, guarding against future settling and cracking, weeds are sealed off and the driveway, sidewalk, patio, or whatever it may be, looks good and continues to look good.