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Concrete cracks concrete movementCONCRETE CRACKS / UNDERCUT / MOVEMENT / DETERIORATION NOTED: "Concrete" means any concrete, masonry or asphalt flatwork around the grounds that is walked or driven on. Driveways are usually cement concrete or asphalt concrete, but some may be cobble stone, brick or block. Although any concrete slab may develop hairline cracks from expansion and contraction of the concrete itself or from vehicular weight, larger cracks, and cracks where one side is lifted or dropped, are generally caused by lifting or settling of the soil and can be, or become, more of a problem Lifting and settling are usually caused by excessive moisture or the lack of moisture. Once a crack opens water may pass through the crack and wet the soil directly below the crack. This wet soil expands at a different rate than the dryer soil farther away from the crack. This causes only that area of the slab which is cracked to lift, thereby causing the crack to get progressively larger. If six inches or more of sand or gravel had been placed under the slab, this would generally have been less of a problem There are caulks made for concrete cracks which are available at most Building Supply Dealers. Caulk the crack solidly and neatly to help prevent water from entering thereby causing it to get larger. Larger cracks should be sealed with mortar or driveway patch using concrete adhesives in the mixture If the crack is caused by an undercut condition the undercut area should be packed with concrete. The broken slab section may have to be removed, the pad (or dirt under the slab) compacted (water is a good compactor) and a new slab section poured This may require the services of a Concrete Contractor, but it is not surprising how easily a property owner can perform these repairs, especially since they are not generally emergency situations If the drive or walk is undercut, it means for one reason or another there is supporting soil missing from under the edge of the drive or walk Many times the cause will be either a broken sprinkler pipe or water runoff on a slope. Sometimes trench-backfill which the drive or walk was placed over has consolidated with water and has settled away from the slab. Small amounts (smaller than a football) are not a problem, but if much larger, cracking of the slab may result. Major undercut conditions should be seen after as soon as possible Broken sprinkler pipes should be dug out and repaired or discontinued Water runoff and soil consolidation can only be dealt with by stopping the water flow by diverting it around the problem area. Tightly packing soil into the depression often will suffice but many times cement concrete will be needed. If you are doing the repairs yourself you will need one or more bags of ready-mixed material, available at all Building Supply Outlets, and something to mix it in, such as a 5 gallon can or large tub or wheelbarrow. Mix it fairly dry so it will "stand up" in the depression and make contact with the affected slab. Concrete can be made more manageable, and will "stand up" better, with the addition of a small amount of lime Contact this company for additional information as needed Contact a Landscape Contractor for resolution of this problem if you feel your efforts are not getting needed results
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