Concrete repair is an important part of keeping structures safe and functional. It also increases the lifespan of the structure and can improve its appearance.
It’s important to understand what causes concrete damage before deciding on the best repair method. The most successful repairs from Level Ground Excavation address the root of the problem and don’t just cover it up.
Concrete problems are common and can be a serious concern in your home. Whether it’s sinking concrete, cracks or unlevel surfaces, it’s important to know how to repair them properly to avoid costly repairs in the future. Concrete concerns should be taken seriously and handled by a professional concrete contractor, who can find the best solution for your needs.
The first step to concrete repair is to figure out what caused the problem in the first place. Once that’s done it’s time to start repairing the damaged area.
Cracks in concrete are a common problem and can be repaired using a variety of methods. Some are easier than others but all have to be done correctly for a long lasting repair.
Narrow cracks are generally easier to repair than wider ones. Regardless of how they are repaired, the key is to prepare the crack for the new repair material. This means grinding the old surface and cleaning out the crack. This will allow the new repair material to bond and cure properly.
If the crack is deep, it may be necessary to prepare the crack by stuffing foam backer rod into the crack. This will take up space and help keep the new concrete repair in place. It’s important to use a backer rod that is slightly larger than the width of the crack. This will prevent the crack from re-opening and will allow for a longer life of the concrete repair.
Once the crack has been prepared it’s time to pour in the new repair. A high quality concrete repair mix is recommended. This is typically a portland cement and aggregate mixture with a polymer added to improve the bond strength. This allows the concrete to bind to the existing concrete, yet still be easy to work with and form into the shape of the repair.
For sunken areas, concrete jacking or polyjacking can be used to lift the sunken section of the slab. This is done by drilling holes through the concrete and then pumping a liquid material underneath the slab to lift it up. This method is much quicker and cheaper than replacing the entire slab.
Preparation
Regardless of the type of concrete repair required, proper preparation is critical. This includes creating the correct concrete surface profile and thoroughly cleaning the area. A contractor must also ensure that the concrete is dry prior to applying any repair materials.
If a structure is experiencing major damage such as widespread cracking, extensive concrete spalling, structural movement or extensive deflection, it may require repairs that involve the replacement of some or all of the damaged concrete section. This type of repair requires special considerations and should only be performed by a professional engineer experienced in concrete construction.
This type of repair usually involves tying the new concrete into the existing structure using reinforcing steel. A complete evaluation should be performed by a qualified engineer to determine the cause of the deterioration, how much replacement is needed and the best methods for doing so.
Before attempting any type of concrete repair, it is important to determine what caused the damage in the first place. This can be done through destructive and nondestructive testing (NDE). Destructive testing will typically involve breaking away a small sample of the concrete for laboratory analysis. Nondestructive testing can include radar, infrared thermography and impact-echo, among others.
In order to get the best possible adhesion between the repaired concrete and existing concrete, a concrete bonding agent should be used. The bonding agent can be applied with a brush, rag or sprayer, but direct application is typically preferred. Typical bonding agents include asphalt emulsions, polyurethanes, epoxy resins and silicates.
Once a concrete bonding agent has been applied to the surface, it must be allowed to dry until it is tacky. This typically only takes a few minutes. Then, the concrete repair material can be applied.
When using a concrete patch, it is important to follow the directions on the package closely. For example, some patch products need to be mixed with water, while others are ready to use right out of the container. It is also a good idea to apply a skim coat of Sakrete Top ‘N Bond over the concrete after the patch has been applied in order to help ensure a smooth, even finish.
Materials
Choosing the right repair material is essential, especially for larger projects. There are many different materials available for concrete repairs, each offering its own unique set of working properties and bonding characteristics. Contractors should consider the specific service environment when deciding on which product to use. Questions to ask yourself include whether the structure is indoor or outdoor, will it be subjected to freezing and thawing, or will it be exposed to chemicals such as deicing salts? The answers to these and other questions will help determine the appropriate material for the job.
The choice of repair materials also depends on the type of deterioration, whether it is a crack or a sunken area. In addition, contractors should consider the amount of time required for the repairs and if the area will be in use during the cure process. If the structure will be in contact with traffic, a flexible material may be needed to prevent damage from vehicles.
Cement-based materials are often used for concrete repairs, but they must be compatible with the damaged structure and able to be worked into place. Some common cement-based materials include unmodified Portland cement (UPC), latex modified Portland cement, rapid-setting nonshrink mortar and polymer concrete. Each of these materials has its own unique set of working properties, such as initial mechanical strength and setting times.
Other considerations when selecting repair materials include the material’s ability to bond to the existing concrete and its shrinkage rate. A high rate of shrinkage can cause debonding between the repaired surface and the existing concrete, so it is important to choose a material with low shrinkage rates. The repair material should also be able to withstand freeze-thaw and other weather conditions.
A bonding agent can improve the adhesiveness of concrete repair materials and increase their durability. Several types of bonding agents are available, including epoxy, polyurethane, urea and others.
The choice of repair material should also take into account the concrete’s initial strength and workability, as well as any special characteristics it needs to possess for a particular application. For example, some repair materials need to be fire resistant, while others must have a high level of flexural strength or abrasion resistance.
Curing
As concrete heals, it gains strength and density. This process is accelerated by water. Water can also cause shrinkage cracking and damage to the concrete surface, but if it is controlled by proper curing practices this problem can be prevented.
Proper curing ensures that the concrete is hydrated throughout its life, delays drying shrinkage cracking until the slab has a sufficient strength to resist it and improves its durability. This is important because damaged concrete is more susceptible to corrosion.
Concrete curing is especially important when working on vertical surfaces or overhead repairs. This is because these types of repair materials are heavier and need to be able to withstand the weight of the material, as well as the added pressures that will be applied. Specially formulated epoxy or acrylic concrete repair products are often used on these types of structures. These repair materials typically have a thicker consistency than standard concrete patching products and create a stronger bond on vertical surfaces.
When working on repairs to overhead or vertical concrete, it is important to use a concrete curing membrane to slow down the drying process. This will prevent cracking, blistering and other damaging effects of the drying concrete.
Once the concrete has cured properly, it is ready for traffic. The finished repair should be tested for strength and durability by applying a load to the repaired surface. This is best done using a calibrated load cell or by performing a push test with an appropriate hand or power tool.
After the concrete has been tested for its strength and durability, it can be sealed with a concrete sealer to protect the surface from damage. There are several brands of concrete sealers available, including a polyaspartic coating that can be used in cold weather.
Concrete repair is often time sensitive, and the right tools and knowledge are necessary to make sure that the job is done correctly. A professional contractor can help you determine the right repair for your needs and provide you with a free estimate for the work. Then you can rest assured that your repair will last.