The formation of horizontal cracks can happen on the surface of the concrete, which particularly depends upon the concrete mix proportion, placing techniques, and the weather in which the concrete has been placed. Some example of these types of cracks has already been explained earlier, such as plastic Shrinkage Cracks, drying Shrinkage Cracks, and expansion Concrete Cracks. On the other hand, vertical cracks formed generally depend upon the soil characteristics and properties, soil safe bearing strength, and the effect of the groundwater table, which is particularly responsible for the settlement of the soil as well as the settlement of the foundation as well.
Horizontal cracks formed generally come under the category of fine cracks, which have a width of less than 5mm, and it very narrow. Horizontal cracks are not generally much detrimental to the foundation and exist in almost all concrete foundations. On the other hand, Vertical cracks formed generally comes under the category of extensive danger cracks(which have a width of 15-20 millimeters) and are very much detrimental to the structure itself.
As horizontal cracks are not detrimental to the structure, it does not propagate through the foundation as well. On the other hand, Vertical cracks propagate rapidly, and if left untreated, they may fail the structure itself.
This is the most conventional method for treating cracks, as many of the local agencies are available for the sole purpose of doing that.
The repair method provides a low-cost solution with possible resources as compared to undermining, which involves high costs as well as additional resources.
Foundation repair methods consume less time as compared to undermining or complete replacement of the foundation, which consumes a large amount of time as well.
Using Epoxy Injection: This is another conventional of repairing concrete surfaces as well. In the case of the Epoxy injection procedure, PVC nozzles are fixed over the total length of the surface. The numbers and the interval of these nozzles are suggested by the repairing agency or by any foundation repair expert. After that, Epoxy is applied over it, which with time, hardens and retains its full strength.
Routing and Sealing: This is a much more common as well as a simpler method of crack repair. Although this type of repairing is adopted for fine cracks also does not pose a serious threat to the foundation and does not involve the restoration of the complete tensile strength of the foundation. In this method, a V-shaped groove is first cut throughout the length of the crack. After that, the surface of the groove is cleaned with a brush. Following that, sealants or sealing agents are applied over the groove, which with time, hardens and gains its stipulated strength.
Stitching the cracks: Although this is one of the uncommon methods of repairing foundation cracks, in many European countries, this type of repairing the system is adopted particularly for pavements. In this type of repair system, at first, several holes are drilled along the length of the crack on both sides. After drilling, the crack is then tied using a binding wire. The binding wire chosen should be as per the required specifications, which prevents the propagation of the cracks further, thus resisting the outward thrust of the concrete as well.
Drilling & Plugging: This is a very cost-effective solution and a good repair method for vertical cracks, which run in straight lines. In this method, a drill is holed on the crack, over which a key is then formed by passing a grout. Further, the remaining portion can be repaired by surface treatments from solution, dry packing, and gravity filling as well. The key formed by passing down a grout resists the propagation of cracks. This method is less time-consuming as well.
Dry Packing: This method is adopted for minor surface cracks. In this method, low water content mortar is hand placed in the cracks, which is then followed by ramming or tamping the surface to even it. In this method, care should be taken to only use low water content mortar so that the mix remains tight and has less Shrinkage as well as to attain its optimal strength.
Structural Reasons: Cracks may be formed in foundation walls for structural reasons. Whenever a required number of extra bars are not provided in the junction of the foundation and walls, cracks can be seen throughout the joints of the foundation and walls. Whenever this type of crack is formed, it becomes very difficult to repair, even with grouting techniques. This design should be made accurately to ensure non-cracking at the joints of the foundation and walls.
Due to Foundation Settlement: Whenever a foundation settles due to soil settlement or due to a rising water table, the wall settles along with the foundation. As a foundation with walls is a rigid structure, due to the settlement of the foundation, horizontal cracks can be formed throughout the walls. To do this, foundation experts must be hired to investigate the soil properties from the groundwater table. If cracks appear on the surface of the walls, grouting may be adopted to ensure that the crack does not propagate.
Due to Growth of Tree Roots: As the growth of tree roots is a potential reason for serious foundation failure, it can adversely affect the foundation walls as well. As a crack appears on the surface of the foundation, it may propagate into the wall, resulting in horizontal cracks forming into the wall as well.