What is considered a hairline crack in concrete?

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.
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How much concrete cracking is acceptable?

Generally, cracks with a width of less than 0.3 mm are acceptable and do not affect the structure. However, they may develop and grow to become structural cracks. Therefore, one should monitor small cracks on houses or structures. Crack width greater than 0.3 mm can create problems for the durability of the structure.
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Is it normal to have hairline cracks in concrete?

Hairline cracks in a concrete slab are rarely a cause for concern. They can be controlled, but not eliminated. A crack in a slab of 1/8 inch or less is typically a normal shrinkage crack and not a cause for concern.
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What is the definition of a hairline crack in concrete?

A.: ACI 116R-90, Cement and Concrete Terminology, defines hairline cracks as cracks in an exposed concrete surface having widths so small as to be barely perceptible.
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Will hairline cracks in concrete get worse?

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.
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Hairline Cracks in Concrete. Its Causes and Prevention.



How thick is a hairline crack?

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.
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Will concrete sealer fill hairline cracks?

Ideally, the sealer has a low surface tension so it readily wets out the concrete and a low viscosity. These two characteristics allow the liquid sealer to penetrate deeply into the crack. Common concrete countertop topical sealers can be used, but getting them to penetrate and fill a hairline crack can be difficult.
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What is the typical crack pattern on concrete floors?

Structural cracks in residential foundations usually result from horizontal loading or settlement. Most (but not all) structural cracks resulting from an applied load (hydrostatic pressure or heavy equipment around foundation wall) are nearly horizontal and appear 16" to 48" from the top of the wall.
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Should concrete crack right away?

Cracking typically starts within 12 hours of the finishing process. Weather conditions will slow or accelerate it. Shrinkage cracking is typically planned for and handled with control joints. One way to handle cracks in concrete is by using control joints.
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What do concrete shrinkage cracks look like?

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.
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How can you tell structural cracks?

As the name suggests, structural cracks occur because of poor construction sites, overloading or poor soil bearing.
...
Telltale signs of structural cracks in your foundation are:
  1. Stair-step cracks.
  2. Cracks on foundation slabs or beams.
  3. Vertical cracks that are wide at the bottom or top.
  4. Cracks measuring 1/8″ in width.
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How can you tell if crack is active?

Active or live cracks are moving cracks or cracks that are likely to grow in width and perhaps length or open/close with changing concrete temperatures. Dormant or stable cracks are unlikely to grow in width or open/close with changing concrete temperatures.
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Does sealing concrete prevent cracks?

The truth is that sealing your concrete driveway won't actually get rid of the cracks that are already there. If your driveway has been pounded over the years by vehicles and the environment, the cracks that are already there won't be eliminated just because we put a layer of our tough and durable sealant over the top.
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Are surface cracks in concrete normal?

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.
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What are settlement cracks?

Settlement. A home may experience some minor cracking as it settles down on its new foundations. The ground underneath the home can compact under the weight of the structure, which causes the home to move downwards. Settlement usually occurs in newer properties, but it soon stabilises.
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Is it normal for a house slab to crack?

ANSWER: Every concrete slab has cracks. Even when you don't see them, slabs are laced with networks of micro-cracks resulting from common shrinkage. When new concrete hardens, shrinkage always occurs. And because concrete is not an elastic material, cracks are inevitable and rarely a cause for concern.
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Should I caulk cracks in concrete?

Concrete Driveway Crack Repair

Even expansion joints in your concrete driveway should be caulked. They can be the biggest culprit of water under your slabs. Notice how the caulking is slightly lower than the concrete slab around it. This protects the caulk from wear and tear of people walking and driving over it.
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Why do hairline cracks appear?

Hairline cracks over doors and windows are likely due to settling. Houses of any age move and shift subtly over time, and the weakest area in a wall is the most likely to crack. A wall is constructed with vertical studs that extend from floor to ceiling.
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Should I worry about cracks in my concrete floor?

Generally, cracks in your floor are nothing to worry yourself over. The only time that you might be concerned is if the cracks start changing vertically, suggesting that there is some settling happening.
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What cracks should I worry about?

Typically, wider cracks signify more serious issues than thinner cracks. Cracks less than 1/8-inch thick are considered stress cracks and are harmless, while cracks 1/4-inch wide and larger are often more serious. Inspect the position of the crack after measuring its width.
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What is the most common cause of cracking in concrete?

There are several reasons why concrete cracks, with the most common being drying shrinkage. Concrete, when placed in the plastic state, is at its largest volume. As the concrete sets and hardens, it begins to shrink. On average, concrete shrinks 1/8 inch in twenty feet.
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How can you tell if concrete is cracked?

Ultrasonic Pulse Velocity (UPV) method is most commonly used to detect the quality of concrete, the position of crack or deepness inside both reinforced and masonry structures. In the ultrasonic inspection, the most widely used modes are longitudinal and shear waves for the propagation.
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Are small foundation cracks normal?

Are foundation cracks normal? Yes, and they usually are no reason to panic. In fact, most cracks in a poured concrete foundation are a natural result of foundation settlement and shrinkage of the concrete during the curing process and can be easily fixed or simply left alone.
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