How to Properly Prepare and Finish a Concrete Repair

Concrete Contractors Colorado Springs is an extensive project that can take time and resources. It can also be expensive and unnecessarily disruptive if structural damage is not detected and addressed correctly.

To ensure your repair is successful, consider the following essentials: surface preparation, proper bonding agents, and a suitable curing regime.


When concrete is repaired, the surface must be prepared properly. Adequate surface preparation enhances durability, improves adhesion, and saves on maintenance costs. It takes time and effort, but it ensures a resilient, long-lasting result. Industry statistics show that poor surface preparation accounts for over 70% of coating failures.

Before any repairs can be made, the existing concrete must be cleaned to remove any debris and contaminants. This can be done with a brush or a hose with a power nozzle attachment. If there are any chemical contaminants, additional rinsing steps may be required. Chemicals that are not rinsed properly can interfere with the bonding and adhesion processes of subsequent coatings.

If the crack is large, a form must be constructed to support the repair material as it sets. This will reduce crack movement and prevent spalling. If the crack is smaller, it can be patched with a concrete mix that is reinforced with steel fibers to improve its strength and durability.

In addition to repairing cracks, it’s important to address the factors that caused them in the first place. Drainage systems are needed to relieve excessive water pressures under floors and behind walls. Rebar is also necessary to resist tensile stresses in concrete. If the problem is caused by thermal stress, insulating materials can be used to reduce these stresses.

Concrete repair should be made with a high-quality, durable cement that is able to withstand the design loads and environmental conditions. It should also be placed correctly, adequately cured, and acceptably finished. This includes surface defects like honeycombing, sand streaking, and form joint offsets.

Depending on the type of repair, some surfaces will require a bonding agent before the new concrete can be applied. This is especially true for thin concrete repair (less than 2 inches). For thicker repairs, a bonding agent is not normally required.

Aside from bonding, it’s vital to make sure the area is dampened before applying the concrete. This will help to keep it from pulling moisture away from the surrounding areas. If it’s not possible to dampen the entire area, covering it with a sheet of burlap and taping it shut should be sufficient. The concrete must also be properly cured. This will not only improve the bond between the old and new concrete, but it will also reduce its tendency to shrink and loosen over time.

Concrete repair requires materials that will adhere to the existing surface and form a strong bond with it. This can be achieved with a variety of products including: conventional replacement plastic and dry pack; acid etching, caulking or coating; injection; grouting; and jacketing. In addition to adhesion, repair materials should provide corrosion protection and meet requirements for the type of service the concrete will experience.

When evaluating concrete repair materials, consideration should be given to their strength, durability, permeability, sulfate resistance, abrasion resistance and tensile and flexural strengths. Often, the location of a repair will dictate the choice of material. For example, some types of repairs may need to withstand heavy vehicular traffic or be located in a wet environment. These conditions will require the use of materials that have good skid and abrasion resistance as well as high tensile and flexural strength.

In addition to these properties, the repair material must be able to withstand the stress concentration at the interface with the host concrete structure. A shear or tension test is typically performed to determine this. For instance, Garbacz [57] used a nondestructive impact-echo technique to evaluate the interfacial stress distribution in a repaired system. This technology utilizes piezo electric sensors to detect the reflection of a shear or tension wave at the interface with the host material. The amplitude of the interface reflection reflects the strength of the shear or tension bond in the repair material-host concrete system.

Another important property of a repair material is its modulus of elasticity and its ability to deform under load. Structural repairs need a material with a modulus of elasticity that is similar to the concrete substrate, while nonstructural repairs can utilize a lower modulus. In addition, the repair material should have low shrinkage compensation to reduce cracking of the new material after installation.

In order to mitigate chloride attack on the host concrete, a cement admixture containing a low water-cement ratio and latex additives is used for concrete repair work. This type of material is called a cement concrete or cement mortar and is typically selected where a large area is to be repaired.

Whether the concrete repair is major or minor, there are standard procedures for placing and finishing the repair material. Suitable methods and materials must be used based on the type of damage. The following steps must be carried out to correctly apply a concrete patch or concrete replacement product: determining the cause and classification of the defect; cleaning the damaged area; saw cutting, removal or demolition of unsound concrete, steel cleaning and coating with bonding agent on existing reinforcement; adequately curing the repaired area, and acceptably finishing the exposed surface.

The first step is to prepare the surface where the concrete patch will be placed. This includes cleaning the area, removing loose particles and rebar, and ensuring it is dry. This is a critical part of any repair because the patch will need to bond properly with the existing concrete.

It is recommended that a hydration inhibitor be added to the mix for this purpose. This will help prevent water loss in the concrete and increase the durability of the final repair.

If the damage is limited to one-half to one square foot areas, conventional concrete placement methods can be used. It is important that the concrete patch be well consolidated, especially around the dowel bars and the patch perimeter. A light hammer can be used to achieve this.

For larger areas of defective concrete, forming may be required. This can be done on-site, but it is preferable to construct forms in advance so the concrete can be placed quickly and efficiently.

Once the concrete is placed, it must be thoroughly consolidated with a vibrator or by hand. This will eliminate the possibility of honeycombing which reduces the strength and durability of the concrete. A light tamping is also helpful to compact the concrete.

Many repair products are designed to obtain high strengths at a relatively early age, which is a desirable feature for contractors who want their repairs to get back into service as soon as possible. However, the ingredients that are used to achieve these high early strengths (type III cement, accelerators, water-reducing agents, etc.) typically lead to a shorter service life of the repaired concrete than would be achieved with a more traditional concrete mixture without these additives.

Concrete repair isn’t just about repairing damage, it’s about making a structurally sound structure that will last. To accomplish that, it’s necessary to properly cure the new concrete. Curing allows concrete to retain moisture so it can gain strength over time and delays drying shrinkage until the concrete is strong enough to resist cracking. Without a suitable curing regime, all the work and materials put into repairing concrete damage will be wasted.

A common concrete problem is honeycombing, a condition that produces small cavities or voids in concrete surfaces. These holes can be caused by improper design, deterioration of the original concrete, exposure to changing temperatures, and excessive loading. In most cases, it’s not possible to see these problems until they are causing serious damage.

The best way to prevent these problems is to take care of concrete repair as soon as it is needed. It’s also important to select the right concrete for the job and apply it correctly. This is why it’s important to ask for references from any contractors you hire and to make sure they are licensed and insured.

When it comes to concrete repair, the most important thing is the integrity of the structure. To ensure this, the surface must be free from dirt, oil, and other contaminants that can weaken or contaminate the concrete. It’s also vital to protect the concrete from mold and mildew, which can cause major structural damage.

Another important factor is the bond between the repair material and the existing concrete. This is determined by the type of concrete used and the surface characteristics of the existing concrete. For example, a low w/c ratio and a high percentage of coarse aggregate is necessary to minimize shrinkage cracking.

The depth and orientation of a repaired area are also important factors to consider. Thicker sections of concrete generate more heat during the curing process, which can lead to thermal stress that reaches an unacceptable level. Additionally, repairs made overhead require thicker repair material than vertical surfaces to prevent sagging.

Finally, the temperature and humidity of a place must be considered when choosing a curing method. Too much heat can cause the concrete to dry too quickly, which reduces its strength and durability. Too much rain can also damage concrete by saturating it with water and forcing it to expand. Using a curing system that controls the temperature and humidity will help to avoid these problems.