The Concrete Repair Process

Concrete repairs address safety hazards and extend the lifespan of concrete structures. This reduces maintenance costs and provides a safer environment for the public. The repair process at starts with a thorough inspection of the damaged concrete. This evaluation classifies the severity of the cracking and identifies if it is active or dormant.


The first step in any concrete repair procedure is the preparation of the area. This includes removing any loose or friable material, including the edges of the damaged concrete. All cracks should be cleaned and prepared for filling with a special hydraulic cement. If the cracks are very thin, this may involve simple spraying with a water jet or a technique called “feathering.” This process involves spreading the concrete mix with a trowel and lightly blending the wet concrete into the surrounding dry concrete.

For most repairs, the best repair product to use is the same mix that was used for the precast section. This is the most cost effective way to ensure proper compatibility. This is particularly important when repairing structural members where shear and bending forces can be transmitted to the new concrete.

When preparing the concrete surface for the repair, the surface profile should be as close to the original surface of the precast concrete as possible. This will improve the long-term performance of the repaired concrete. The concrete should also be free of any contamination that would prevent topical materials from adhering or penetrating into the surface. This could include old sealer, rust stains, mildew or other surface contamination.

Often, concrete surfaces with damage due to corrosion require treatment before the repair can be made. Grit blasting, or the application of chemical treatments, can be used to remove corrosion products and return the concrete surface to its original state.

In addition, any areas of spalling need to be repaired. This can be done by filling or patching the areas of rough and pitted concrete. Joints that deteriorate require repair, as well as the re-colking of the joints to ensure they can expand and contract without damaging the surrounding concrete. Levelling and slab jacking can be used to lift unlevel concrete sections.

Once the evaluation, product comparison and preparation is completed, the repairs can begin. It is very important that the causes of the damage be identified and tackled so they can be prevented from recurring. Otherwise, the same concrete damage will occur over and over again and result in unnecessary repair costs.


The first step in concrete repair is to prepare the area. Remove any debris and if necessary, add and compact new backfill material. If damage to the subbase is caused by the removal process it should be repaired with a layer of good quality crushed stone. If this is not possible, the damaged areas should be excavated down to a suitable depth and a fresh layer of backfill material added. Ideally, a compactor should be used that is small enough to maneuver in the confined patch area.

If the repairs involve replacement of concrete, a bond coat must be applied to the old concrete surface. This is usually a mix of equal parts portland cement and sand. Alternatively, epoxy resins or latex emulsions with portland cement may be used as bonding materials. Often, a resurfacer will be used to smooth the surface of the concrete prior to applying the bond coat.

Once the concrete has been resurfaced, it should be inspected to determine if a proper bond exists between the old and new concrete surfaces. If not, the surface of the concrete must be sandblasted to prepare it for a new coating.

The concrete repair materials must be compatible with the existing precast concrete in terms of both mechanical attributes and curing conditions. For example, the compressive strength of a precast concrete panel should not be less than 4,000 psi. If this is not possible, a stronger bag mix that cures rapidly may be needed.

In addition, the repair procedures must be compatible with any environmental and safety requirements. For example, some locations have restrictions on the type of equipment and the types of materials that can be used. This can require special considerations for the placement of repair materials that are odorous, toxic or combustible.

Larger repairs that involve replacing sections of concrete with new concrete will usually require the use of forms. These must be designed to be strong, lightweight and mortar-tight. It is also important to construct the form in stages so that placing progresses without delay. For example, the front panels of a form should be constructed as placing progresses so that the concrete can be removed quickly if a problem occurs.


Concrete structures are subjected to a variety of environmental factors that can cause damage and deterioration. These factors can affect the structural integrity of the structure and compromise its safety and stability. Repairs to these structures are required to address this damage and prevent future deterioration.

The repair process is different depending on the type and severity of the damage. Structural repairs can involve repairing and replacing damaged concrete sections. It can also include repairing or adding reinforcement to strengthen the concrete structure. Decorative concrete repairs can be more straightforward and involve filling or patching cracks in the concrete surface.

The first step in repairing concrete is assessing the extent of the damage and its effect on the structure’s serviceability. This helps to determine whether the damage can be repaired or if it needs to be replaced. In some cases, the damage may be so severe that it is not safe to use the concrete in question and needs to be replaced entirely.

Next, the concrete should be cleaned to remove any dirt or debris that has built up over time. This can be done using sandblasting or shotblasting. Once the concrete is clean, a bond coat can be applied to the surface. This is usually a mixture of one part cement and two parts sand, which is spread into the cracks using a trowel. It is important that the bond coat is not allowed to set before the concrete is poured.

Once the bond coat has been applied, the cracks can be filled with concrete. It is important to ensure that the concrete is not poured too quickly, as this can cause it to settle unevenly and lead to further damage. It is also important that the cracks are thoroughly filled and that any air bubbles are removed. Once the concrete has cured, it should be checked for any remaining cracks and sealed if necessary.

Another method of concrete repair is epoxy injection. This is a quick and cost-effective method that can be used to repair small cracks in concrete. It is also effective for repairing concrete columns and slabs. This technique is particularly useful when a structure has been exposed to cyclic loading, freezing and thawing cycles, or corrosion of steel reinforcing bars.


After the concrete is poured, it needs to be adequately cured. This will enhance its quality and improve the longevity of the concrete structure. Proper curing will enhance its strength, durability, water-tightness and abrasion resistance. However, if not done correctly, the concrete can fail prematurely. This is why it is important to take the time to evaluate concrete damage, properly prepare the damaged areas, and apply a quality repair material.

Repairing precast concrete is usually accomplished by placing a fresh concrete mix into the damaged area and bonding it with the existing concrete. The concrete should be a similar mix to the concrete that was originally cast. This will ensure that the mechanical attributes of the new concrete – modulus of elasticity, permeability and thermal expansion – are compatible with the original concrete base.

The quality of the repairs will depend largely on the preparation and mixing of the concrete, the amount of water used, the type of curing technique used and the environment in which the concrete is placed. Some of the more common curing methods include ponding, immersion, spraying and fogging. In all cases, care should be taken to avoid large temperature differentials within the concrete mass and the curing environment. This will prevent cracking caused by thermal shock.

During the curing process, the concrete should be covered to prevent evaporation. This will allow the concrete to maintain a uniform moisture level, which is essential for proper hydration and strength development. A cover will also help to reduce surface contamination and the occurrence of air bubbles within the concrete.

In addition to a cover, other curing techniques may include the use of plastic sheets, paper bags, aluminum foil and insulated blankets. All of these will aid in retaining the concrete’s moisture and help to reduce evaporation, which will accelerate the rate of strength development.