Concrete Crack Repair Methods – Part II

Routing and Sealing

Closing and routing of cracks in concrete can be utilized in conditions where replacement is unnecessary and it is needing remedial repair. This process requires enlarging the crack along its face that is exposed and completing and closing and it with suitable joint sealant. This is easy in comparison to the methods and experience needed for epoxy injection and is a widespread technique for simplest cure. The process is most applicable to roughly level horizontal areas including streets and surfaces. However, routing and closing may be accomplished on vertical areas (with a low-sag resin) as well as on rounded surfaces (pipes, loads and rod).

Routing and closing is employed to treat both fine cracks, separated chips, and larger fractures where structural crack repair is required. A standard and effective use is by closing chips on the real area where hydrostatic stress is utilized, or where water stands for waterproofing. This treatment lowers the other difficulties of water seepage which produce surface spots or the concrete or to reach the reinforcing steel.

The concrete sealants may be materials including mortars, or epoxies, urethanes, silicones, polysulfides, asphaltic materials. Cement grouts must be avoided of due to the possibility of cracking. For surfaces, the sealant should really be effectively tough to support the traffic that is expected. Sufficient sealants must not be fragile and must be able to tolerate deformations.

The process consists of organizing a groove at the floor running to a depth, typically, from 1/4 to at least one in. (6 to 25 mm). Hand-tools or pneumatic instruments tools work extremely well. The groove is then cleaned by water blasting or oxygen blasting, and dried. A sealant is positioned into the dried groove and permitted to cure.

A bond breaker may be installed at the bottom of the groove to allow the sealant to change shape, without a concentration of stress on the base where the crack persists. The bond breaker may be polyethylene tape which won’t bond to the sealant.

Repair of concrete

Stitching

Stitching requires drilling holes on both sides of the fracture and grouting in u-shaped metal devices with feet (stitching dogs) that span the crack. When tensile strength must be reestablished across major chips stitching works extremely well. The sewing process consists of drilling holes on both sides of the fracture and anchoring the legs of the staples inside the holes, with either an epoxy resin or a non-shrink grout-based bonding system.

Extra reinforcement

Conventional reinforcement

Cracked reinforced concrete bridge girders have already been successfully fixing in-place reinforcing bars with epoxy. This technique secures the crack by drilling holes that intersect the crack plane at about 90-deg and filling the hole with epoxy and setting a strengthening bar into the drilled hole. Usually, No. 4 or 5 (10 M or 15-M) are utilized, advancing at least 18 in. (0.5 m) each side of the bust. The bars may be spread to match the the repair. They could be put in any desired width, depending on the layout standards and also the in-place reinforcement’s location.

Post-tensioning is often the preferred option whenever a key part of an associate has to be strengthened or once the fractures that have created should be sealed. This method uses prestressed bars to apply a compressive force. Ample anchorage must be offered for the pre-stressing metal, so that the issue won’t just move to some other the main structure and repair will become necessary.

Drilling and promoting

This process is applicable when affordable direct lines are run in by chips and therefore are available at one end. This method is most often used-to repair vertical cracks. A hole, usually two to three in. (50 to 75-mm) in size, should be drilled following the crack. Grout is filled into the hole to form a key.

The grout key prevents transverse movement of concrete next to the crack. The main element will even decrease leakage through crack and loss of soil from behind a retaining wall. If water-fastness is important and structural load is not, the hole may be stuffed with a water-resistant material in lieu of grout.

Gravity Filling

Low viscosity monomers and resins can be utilized to seal cracks with area widths of 0.001 to 0.08 in. (0.03 to 2 mm) by gravity filling. Large-molecular weight methacrylates plus some low-viscosity epoxies have been used with success. Lower viscosity allows smaller cracks to be filled. The normal method is always to clean the outer lining by waterblasting or air blasting. Moist areas ought to be to be dry many days to acquire the best crack filling.

The depth of filling of the sealant the crack filling’s effectiveness can be determined by taking cores. Shear or tensile checks can be performed together with the weight applied parallel to the fixed fractures (so long as reinforcing material isn’t present in the core or nearby the failure location). For a few polymers the failure crack will arise outside your fracture that is repaired.