Hairline Cracks In Concrete Slab
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Im getting ready to install a 2 post car lift in my garage. It so happends one of the post will have to be anchored over some hairline cracks. Im not sure if these are just surface shrinkage cracks or they go right through the slab. Iv tried to insert a pin into the crack but it will not go in.The concrete must be stronge in this area for the. No one who pays a concrete contractor wants it to crack or thinks it should. A high solids sealer will not fill the cracks, but epoxy injection would. The sealer will simply seep all the way through the crack and into the stone base. Yes, the crack goes all the way through the slab. It doesn't magically stop halfway through.
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Very thin hairline cracks in random or irregular hexagonal patterns that are very shallow, usually less than an 1/8 of an inch deep, are often called crazing cracks. They are caused by improper troweling and placement of the concrete; the thin top layer of concrete dries out faster than the rest of the concrete, thus these hairline cracks. The photograph of cracks above were taken of shrinkage cracks in a concrete slab floor in a home built in 2006. The cracks in this case ranged in width (measured across the crack) from 'hairline' (less than 1/16') to about 3/32' in the basement floor slab of this particular home. They may appear larger.
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You just had a fresh concrete driveway poured and it cracks. Now what?
Dear Angie: I just had a new concrete driveway poured and the very next morning, several cracks showed up in the concrete. My contractor says that this is normal and will not affect the integrity of the concrete. My contractor had a representative from the material supplier come out and take a look and he also said that this was normal.
I looked at my neighbor’s 1-year old driveway, though, and there is not a single crack in it. I elected to hold the final payment until I get a satisfactory answer. What do you think? Is this normal? – James B., Chicago.
Dear James: Unfortunately, cracking is pretty common in concrete, especially during the first 30 days, while it’s curing or setting up. If a contractor does it right and the conditions are ideal, the cracks can be virtually unnoticeable from plain view, except the homeowner’s prudent eye.
RELATED: How to Extend the Life of Your Asphalt or Concrete Driveway
RELATED: Why Concrete Cracks and How to Prevent It
There are a number of reasons why concrete cracks. The most common is because concrete shrinks as the excess water evaporates and it hardens. Unfortunately, too often contractors add too much water to the mix, which makes it easier to apply but also more vulnerable to cracking. Concrete can also crack if it dries too quickly.
Weather conditions — extreme temperatures, rapid temperature changes or conditions that are too wet or too dry — also play a major factor in how well concrete cures.
Another consideration is if the contractor used control joints and spaced them properly. Contractors place control joints in the concrete with the anticipation that it will crack. Also called “relief joints,” control joints are the straight lines or grooves you typically see at regular intervals on concrete sidewalks, driveways and garages. Their purpose is to relieve the pressure that leads to cracking with the cracks essentially forming in those grooves, so that, cosmetically, it’s barely discernible.
What are the benefits of a concrete driveway?
Check out the video below to determine if a concrete driveway is the right choice for you.
Crack may lessen when concrete settles
I recommend you give it a little more time. Concrete takes a good month or so to really set up. By then, the cracks could be undetectable. The method the contractor uses to cure the concrete plays a big role on how well it holds up. Cement requires a moist, controlled environment to gain strength and harden fully. Talk to your contractor about his method to cure the concrete.
It expands and contracts in response to the temperature. If there are fluctuations in the weather during and immediately after the pour, which is known to happen in Chicago, that can also create problems. Contractors must be good judges of those situations to determine when to seal the concrete to reduce the chances of it cracking.
Those many variables alone could have played a factor as to why your neighbor’s driveway has no visible cracks.
RELATED: Angie's List Guide to Driveways
All that said, if after it cures, the cracking is severe — big enough that you can fit a quarter in the crack — that’s an indication of a problem and deserves a conversation with your contractor about an agreeable solution. You were smart to withhold the last payment. I advise homeowners to do that precisely for situations like yours. You now have leverage in case those cracks do become worse instead of better.
If you continue to have concerns about the integrity of the concrete, consider bringing in an independent home inspector or structural engineer to determine if there’s a more serious issue.
RELATED: Paver Driveway Makes Dramatic Change Over Concrete
Angie Hicks is founder of Angie's List. Email questions to askangie@angieslist.com or tweet to #AskAngie. Follow Angie at @Angie_Hicks.
Editor's note: This is an updated version of an article originally posted on June 21, 2012.
Did your concrete driveway crack after being poured? Tell us about it in the comments section below!
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A simple, permanent repair for cracked concrete walls
Pal dvd player download. Concrete consists primarily of cement, sand, gravel and water. As the water in the slurry evaporates, the remaining ingredients cure into a hard, monolithic slab. Unfortunately, the curing process causes the concrete to shrink slightly, often resulting in hairline cracks. Larger stress cracks occur when a house settles or the ground beneath it shifts. These types of cracks typically don't threaten the structural integrity of the house, but they do create an entry point for groundwater, insects and radon gas. Here, we'll show you a simple, effective way to patch cracks in poured- concrete walls.
If you notice large, recurring cracks or bulging walls at your house, don't try to fix these conditions yourself. The cracks might indicate a more serious structural problem; call in a structural engineer for an in-depth evaluation.
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Repairing Cracks In Concrete
Repairing the Crack
Several masonry patching products, such as hydraulic cement, do an adequate job of filling cracks in concrete walls. However, these concrete crack repair products can fail after a few years if your foundation or retaining wall continues to move slightly, leaving you with little choice but to chip them out and start all over again.
We repaired a foundation wall, which had an 8-ft.-long crack that leaked water into the basement during periods of heavy rainfall. To permanently patch the crack we used an epoxy-injection system from Polygem, called the Liquid Concrete Repair Kit (about $60). Each kit contains a two-part epoxy crack sealer, two 10-oz. tubes of Liquid Concrete Repair (LCR), a viscous epoxy that comes in a caulk-type cartridge, and seven plastic injection ports that deliver the LCR deep into the crack. There's enough material in each kit to repair a 1/16-in.-wide x 8-in.-deep x 8-ft.-long crack.
Acceptable Cracks In Concrete Slabs
Before you start, check to make sure the crack is dry. If the crack is slightly damp, dry it with a blow-dryer, then wait 15 minutes. If it remains dry, proceed with the repair. However, if the dampness returns, water is still seeping into the crack and you'll have to wait for it to dry out on its own.
Hairline Crack Sealer
First, scrub the crack clean of any loose concrete, paint or old filler using a wire brush. Remove all dust and debris with a shop vacuum.