The Basics of Concrete Repair

Concrete Repair is an ongoing process that preserves and extends the life of safe, functional, aesthetically pleasing concrete surfaces. It is important to identify and address concrete defects promptly to minimize damage and repair costs.

Concrete Repair

A professional contractor can complete repairs quickly and efficiently, saving you time and money in the long run. They also offer warranties and insurance to give you peace of mind.

The preparation process in concrete repair is a crucial step that ensures the success of a repair. This includes removing any unsound concrete, contamination, and surface detritus before installing the repair. It also involves using the right tools and materials for the job at hand. The wrong materials or methods can lead to failure within a short amount of time. Professional contractors have the expertise and experience to evaluate a structure’s condition and determine the correct repair method for it. They can also provide preventative maintenance to help keep structures in good condition for longer.

The type of damage that needs to be repaired will influence the choice of a repair method. For example, structural repairs can include reinforcing a structure with steel bars or other materials. Structural repair methods are generally more expensive than surface repair methods, but they can provide greater strength and longevity.

Choosing the right concrete repair material is another important aspect of the preparation process. The concrete repair product should be suitable for the structure’s service environment and have properties similar to those of the parent concrete. These properties include modulus of elasticity, freeze-thaw durability, and permeability.

When selecting a concrete repair material, the contractor should consider its early-age strength, as well as its durability and cost. Some products can achieve high strengths very quickly, but these higher strengths are often achieved at the expense of durability. The contractor should also look at the chemical resistance, abrasion resistance, and thermal expansion characteristics of the concrete repair product.

Once the repair material has been selected, it’s important to prepare the concrete surface for application. This will vary depending on the type of surface and the condition of the concrete. For example, if the surface is very smooth and in good condition, it may only need to be vacuumed or washed. In contrast, if the concrete is heavily contaminated or has low cover, more aggressive surface preparation may be needed. This can include grinding, scabbling, needle scaling, shot blasting, and scarifying.

During the preparation stage, it’s also important to protect surrounding areas from moisture. This is especially true for the expansion joints and foundation of the concrete structure. Moisture in these areas can cause corrosion and deterioration, which can be costly to remove and replace. It’s also important to avoid getting water in cracks and expansion joints, as this can lead to structural problems in the future.


Concrete patching is a common repair method for spalling and cracks. However, before using this type of repair it is important to understand that surface repairs provide only temporary relief and are not designed for structural damage. It is also important to determine the cause of the damage and fix it if possible, otherwise the cracks will likely reappear.

Before applying any patching material it is essential that the surface be thoroughly cleaned and free of any loose debris. This can be done by sandblasting, shot blasting or water washing. Once the surface has been cleaned it should be dampened, this is most easily accomplished by spraying it. This helps to prevent the new patching materials from pulling moisture out of the old concrete and reducing its strength.

The area that is to be repaired should then be primed with a bonding agent. This can be a powder that is mixed with the patching material, or it may be a liquid additive that is applied directly to the concrete surface. Most bonding agents need to be applied just prior to the application of the repair material. Once the concrete repair product has been placed it should be troweled properly to ensure no air gaps are present and to create a smooth, uniform surface. The concrete should then be allowed to cure per the manufacturers recommendations.

Some products offer high early strengths, which is a great selling point for some of them, but these materials may produce heat that is detrimental to the concrete. Additionally, some of these materials are prone to shrinkage cracking. In order to minimize these problems it is best to use a standard repair material that does not have any of the added ingredients that are used to achieve a high early strength.

Another option for concrete repair is the injection of epoxy. This is an excellent method for cracks that are shallow, as it allows the entire depth of the crack to be filled. This type of repair is best for non-structural cracks, such as honeycombing.

Other options for concrete repair include the use of cathodic protection (CP). This involves the placement of a small permanent current in the concrete with the goal of halting corrosion of steel within the concrete. This can be an effective long-term solution for many types of deterioration, such as spalling and delamination.


The concrete repair process can involve various methods depending on the severity of the deterioration. Some of the more common repair methods include:

Minor Defects

Small cracks that don’t penetrate to steel reinforcement are cosmetic in nature and can be repaired by filling them with dry cement. The existing concrete must be thoroughly dampened to prevent the repair materials from robbing moisture from the old concrete. This is often accomplished by placing a damp burlap sheet or covering the entire area with a larger sheet of plastic and taping the edges to hold in the moisture.


The overlay method involves applying a thin layer of new concrete or specialized overlay material on top of the existing concrete surface to restore its appearance and strength. This is commonly used for sidewalks, driveways and other outdoor surfaces. This type of concrete repair may be done using a spray application system or by hand laying the material.

Joint Repair

Joints in concrete are designed to allow for expansion and contraction of the structure. When these joints deteriorate, they can cause cracking of the surrounding concrete. Repairing these joints is important to ensure that they are able to withstand the forces placed on the concrete by movement.

Structural Defects

Structural problems can be a result of foundation damage, poor construction practices, ground movement, overloading or just settling that occurs in all buildings. It is essential that these structural defects be addressed to avoid future costly repairs or complete collapse of the building.

Voids under concrete slabs can be filled by injection techniques. A type of sand-cement slurry is pumped into holes drilled in the slab foundation to fill the voids. This type of repair is sometimes referred to as “slab jacking”.

Other void filling methods include the use of epoxy or urethane injections. These types of injections are typically used for thin cracks that are difficult to reach with other methods.

Many concrete repair products contain bonding agents that improve the adhesion of the repair materials to the existing concrete. The bonding agent can be added directly to the concrete mix or applied as a primer to the existing concrete before adding the repair materials. When using a bonding agent it is important to follow the manufacturer’s directions regarding application, especially when the bonding agent requires drying to a tacky state before applying the concrete repair materials.


When repairing concrete cracks, there are two goals: structural bonding and stopping water flow. For structural bonding, epoxy injections can be used. For a waterproof seal, urethane concrete sealants can be applied. Both types of sealants require that the cracks be clean and dry. If any dirt, gravel, or other debris is in the cracks it will keep the repair materials from adhering and could cause the cracks to reappear once they are filled.

Before applying any filler or sealant, it is a good idea to chisel the crack to widen it and make sure the edges of the crack are well defined. This will help the new material adhere to the existing concrete and not flake away as it dries.

After chiseling the crack, it is important to clean out the opening to remove any particulate matter that may be blocking the bond. If necessary, a wire- or stiff-bristle brush can be used to scrub the area and then rinsed with a pressure washer. It is also a good idea to blow out any areas that cannot be accessed by spraying.

Once the surface is cleaned, a bonding adhesive should be applied to the existing concrete to improve the adhesion of the repair materials. This step is not always done and is a mistake. This material is available in liquid form and can be applied with a paintbrush or sprayed on. Once it dries to a tacky consistency it can be covered with the filler or sealant.

There are many products available to fill and seal concrete cracks, spalls, and leaking joints. A good quality concrete floor will last much longer if the cracks are sealed to prevent water penetration and freeze/thaw damage.

If your concrete structure has any cracks that need to be repaired, you should seek the services of a professional concrete contractor who is experienced in this type of work. They will have the expertise and high-quality materials needed to ensure that your repairs are done properly and will last. This will save you money in the long run and will protect your investment in a quality product.