Concrete foundations are of two types – poured concrete and concrete block. Poured concrete is a modern manner of laying foundations, while concrete blocks are more traditional. Concrete blocks are preferred for their visual appeal and strength. Yet, as time passes, there may be degradation of concrete.
The prime cause of cracks in concrete foundation is seepage of water. Such cracks caused due to leakage of water are thin and hairline. They may widen over time, but they are present only in those areas where the seepage occurs. In order to repair leakage cracks, it is necessary first to investigate the source and the point from which the leakage originates.
There may be other reasons for concrete foundations to crumble. Soil may lose its moisture content in summer. There may be underground roots which may wither and die. Such natural causes make the soil shrink and hence the foundation may move. Though this movement is gradual, overtime it will cause cracks to occur. These cracks will be large gaping ones, running across the entire length of the foundation. They may even be in the form of tiny holes in certain places.
Whatever be the reason, cracks in the foundation are very perilous if ignored. Repair must be done as soon as possible. Difficulties involved in the repair process are influenced by how big the cracks are.
For tiny moisture created cracks, the repair is relatively simple and can be done by almost anyone. These cracks must first be brushed clean with a wire brush. A jet of water may be passed to remove any loose concrete particles within the crack. The crack is then allowed to dry completely and filled with concrete caulk. If the crack is large, then it is packed with patching materials that are specifically available for concrete. These patching materials must be wet when applied. They are limestone based, and they expand as they dry, filling up the crack completely. The finishing touch is to apply a sealant to the repaired crack.
But if the crack is sinister and not the do-it-yourself kind, then it is most prudent to shell out a few dollars and hire some good repairmen. Such cracks occur due to rods which may have rusted inside and snapped or because of deterioration of the materials present within the concrete. Some leakage cracks when ignored can also reach dangerous levels. Such cracks are more found in poured concrete.
Contractors treat the concrete foundation with urethane injections to extract the embedded water. They may even excavate the area around the foundation and replace the faulty tile or construct a provision for the water to lose contact with the foundation.
The principal function of a foundation of a home is to transfer the weight of a structure to its underlying soil and rocks. One of the factors that bring about the need for foundation repairs is improper foundation settling. Foundation settlement can devalue structures and also render them unsafe. Building on expansive clay, compressive or improperly contracted fill soils and improper maintenance in and around foundations are some of the major reasons of improper foundation settling. Another reason for improper foundation settlement is undetected or unsuspected air pockets in the ground below the area of construction. These may cave in and cause the integrity of the foundation to be compromised.
General symptoms of a structure needing foundation repairs are bulging or cracked walls and doors that don’t close properly. Building on expansive soils is the main culprit for foundation settlement. When only one part of the foundation either settles or heaves, cracks are formed in the foundation. The exterior warning signs of improper floor settling are rotation of walls, displaced moldings, cracked bricks and foundation and separation around doors and windows from the walls. Interior warning signs of improper floor settling are cracks on the floor, sheet rock and misalignment in doors and windows.
There are many ways of doing foundation repair. Cement, stone, steel or wood were used extensively in past techniques. They would be forced into the ground in a bid to salvage the strength of these foundations. However, this type of repair work has been known to be futile. Two of the most successful ways of foundation repairs are slab jacking and the Piering method. Piering is also known as hydraulic jacking.
Slab jacking is the process of adding grout beneath a slab or beam. This produces a lifting force and restores the said beam or slab to almost its original elevation and adds to its strength. Care should be taken that the amount of sand should be perfect while adding grout.
During Piering, steel posts are driven through unstable soil. Hydraulic jacks are used to stabilize concrete slabs which are weakened due to the changes taking place in the underlying soil. Steel beams are used in the Piering method because concrete has great compressive strength. Though Piers are able to transfer huge downward loads without the help of reinforcing steel, steel is used in the piers for prevention of the pier from being pulled apart or sheared by forces of the expansive soils. The repairs normally take 21 to 30 days, however this time frame can vary depending on soil conditions and weather delays.
This article is for general knowledge only, always consult with an expert regarding any structural design issues or faults.
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