While there are some cracks that homeowners can repair themselves, most require professional attention. Especially for major structural repairs that can cause safety hazards.
The most important thing is to have the damage evaluated by a contractor before starting any concrete repair work. That way, the correct type of repair method can be selected. Concrete Contractors Colorado Springs can help you with your concrete projects.
Choosing A Repair Material
When it comes to concrete repair, contractors often opt for a product that has worked well on previous projects. However, job sites and types of damage vary significantly, so choosing the right repair material is important to ensure the repairs last. This requires considering a range of working properties, such as strength, bonding characteristics, and flowability. Fortunately, ready mix manufacturers offer a variety of repair products to suit your needs.
In addition, determining the type of damage can help narrow down which properties are most important for your repair job. For instance, if you’re dealing with corrosion or chemical attack damage, permeability is likely to be a priority, while a low modulus of elasticity may be more important for mechanical damage.
Contractors should also consider the geometry and structural requirements of the repair area when selecting a repair material. A range of repair materials exist that are suited for horizontal, vertical, and overhead installations and that can be poured, pumped, or injected into large or hard-to-access voids.
Constructability is another factor to consider, as it impacts the ease with which a repair material can be placed in the desired location and how quickly. A range of constructability properties are available, including permeability, slump, and flow, hang / stickiness, and curing time. These features can be adapted to suit specific installation procedures, such as form-and-pour repair materials, pre-placed aggregate repairs, trowel-applied vertical and overhead repairs, or low velocity wet sprayed shotcrete repairs.
While choosing the right repair material is important, surface preparation is equally critical for a successful job. A nylon brush can remove dust and debris from the damaged surface before applying the repair material, while pressure washing can further clean a concrete structure and ensure it’s dry before placing the material. A quality primer must also be used to ensure the repair material bonds properly with the existing concrete.
Contractors should look to concrete repair experts for guidance and support when choosing the right repair material. This includes reaching out to colleagues and consulting industry resources. In addition, contractors should make a point of visiting trade shows and attending workshops to learn from their peers.
Preparation
For repair materials to bond successfully with an existing concrete surface, the substrate must be prepared properly. This is critical, as even the best repair products can fail to bond if not applied to a sound substrate.
The preparation of the concrete substrate may include cleaning, sandblasting, shot blasting, grit blasting, power washing, chemical cleaning, or scarification. The objective is to remove all deteriorated and damaged parts of the concrete, and any previously applied coatings or corrosion inhibitors, that could act as bond breakers.
It is also important to eliminate all moisture in the concrete and to ensure that the concrete is dry before attempting repairs. Wet concrete will swell and deform, making it difficult to work with and shortening the life of the repair material.
A good way to determine the condition of the concrete and the extent of the damage is a visual inspection. However, a more thorough evaluation is typically necessary and may include destructive or nondestructive testing, coring of cores for laboratory analysis, the use of radar or impact-echo technologies to identify delaminated areas of the concrete, and chemical analyses on samples of the concrete and steel reinforcement.
In structural repairs, it is often beneficial to select a repair material with a modulus of elasticity similar to the existing concrete. This will help to reduce the tensile stresses induced in the repaired concrete by restrained drying shrinkage and will protect embedded steel from corrosion.
Regardless of the type of concrete being repaired, it is always essential to avoid chloride contamination of the reinforcement. This can be done by thoroughly cleaning the reinforcing steel before applying any repair material. In addition, it is recommended that the surface of the steel reinforcement be clean enough to provide a sacrificial oxide coating that will prevent further deterioration and promote adhesion with the new concrete.
Finally, it is crucial to evaluate the quality of the preparation by conducting a tensile pull-off test on a representative sample area of the cured repair. This will serve as a benchmark to ensure that the tensile strength of the repair bond meets the engineer’s specifications.
Bonding
The bonding between the repair material and the concrete substrate is an important aspect of a successful concrete repair. If the repair material fails to bind to the old concrete, the repair will not last, and future repairs will be needed to address the original problem.
The quality of the bond between the repair material and the substrate depends on several factors. These include the surface preparation, the type of repair material, and moisture content. The substrate must also be free of contaminants such as oil, paint, or dirt that could act as bond breakers. Finally, the repair materials must be compatible with the concrete in terms of chemistry and strength.
Contractors should consult with a concrete mix manufacturer to ensure that the repair product they choose is appropriate for the project at hand. They should also consider the geometry and structural requirements to make sure that the repair material can withstand the intended stresses.
It is essential that the new repair material bonds well with the existing concrete to withstand the imposed loads. To achieve this, the repair material must adhere to the concrete with a strong shear and tensile bond. In addition, the shear and tensile strengths of the repaired concrete must be comparable to those of the original concrete.
Several techniques have been developed to improve the interfacial adhesion between repair materials and substrates. These methods include sandblasting to increase the roughness of the substrate surface, the use of interfacial coupling agents, and the addition of fibers to repair materials. Flexural tests, slant shear tests, push-out tests, and pull-out tests are used to evaluate the shear and tensile strength of the interface between the repair material and substrate. The core pull-out test is a nondestructive method to evaluate the tensile strength of the interface between geopolymer and concrete repair materials.
A flexural test involves clamping a square steel block to the sample and applying a vertical load. The test is repeated until the specimen breaks. This technique is an alternative to the slanted shear and push-out tests.
Installation
Concrete repair is essential to ensure safety and prolong the lifespan of structures. Cracks, spalling, and uneven surfaces can pose tripping and falling hazards for people and animals, and cars may damage the structure when driving over it. Addressing these issues early and regularly will prevent further damage and save money in the long run.
The first step in concrete repair is determining the cause of deterioration. This can be done through a structural evaluation, a review of design and construction documents, destructive and nondestructive testing of the concrete, a visual inspection, and maintenance records. Once the underlying issue is determined, the appropriate repair method and materials can be selected.
There are many different ways to repair concrete, from using patching mixes to pouring new concrete. The location of the concrete has a big impact on which type of repair is required. For example, if the concrete is exposed to heavy vehicular traffic, materials that set quickly and provide good abrasion resistance are needed. In addition, some locations have environmental restrictions that limit the type of equipment that can be used.
Another important aspect of concrete repair is preparing the surface. This involves chipping away deteriorated concrete, cleaning the area, and applying a liquid membrane-forming curing compound to the repaired area. It is also a good idea to test the strength of the concrete by pulling it and measuring the psi. A higher psi indicates that the repair will hold and last longer.
In the past, many repairs were done by injecting concrete into cracks or voids. This can be costly and time-consuming. A better option is to use PolyLevel, which uses a two-part polyurethane resin to fill voids and lift sunken concrete back to its original position. It’s quick, less invasive, aesthetically pleasing, doesn’t retain moisture, and requires little cleanup.
Whether it’s reforming an edge for a residential concrete step or injecting a concrete repair material into a large parking deck, proper installation is key to ensuring the longevity of your concrete structure. Concrete repair contractors can help you choose the right materials for your project, install them correctly, and perform any necessary maintenance to extend the life of your concrete structure.
