Concrete Repair Morgantown WV involves a condition evaluation to determine the cause of deterioration and select the right repair methods. Concrete contractors can use nondestructive testing to evaluate the structure, including impact-echo and radar. Other important considerations are the type of repair material, surface preparation practices, and curing practices. These can impact the longevity of a concrete repair.
Surface preparation is key whether you’re working with concrete cracks, holes, or something more significant in your project. Before you start, ensure the damaged area is free from loose concrete chips, dust, and other debris that could prevent the new concrete mix from bonding correctly with the existing concrete surface. If necessary, clean the damaged area with a pressure washer. This step is crucial if you use acid to treat the cracks; a clean concrete surface will have an easier time adhering to the new material.
Once you’ve determined the type and extent of the damage, it’s time to decide which repair method is best for you. Routing and sealing is a popular solution for dormant cracks that are not structurally significant. It involves enlarging the exposed face of the crack and then filling and sealing it with an appropriate sealant. The sealant must be selected carefully since different materials have varying tolerances for crack movement. The higher the flexibility of the sealant, the more it can tolerate crack growth and movement.
Another option for repairing cracked concrete is epoxy injection. This technique involves applying a surface cap of non-sag epoxy to confine the crack, drilling holes at close intervals along horizontal, vertical or overhead cracks and injecting them with an epoxy that bonds or welds the cracks together (Photo 4). This method is considered a structural repair because it restores the concrete’s as-designed strength and stiffness. It does not, however, correct problems related to design or construction errors that may affect load-carrying capacity and safety.
If you’re dealing with deep cracks, it’s important to determine if they are structurally significant or not. This is because they can cause the structure to weaken and possibly collapse. If the cracks are caused by intrinsic volume changes such as drying shrinkage or thermal expansion and contraction, they are likely not to be structurally significant.
You can use this information to help select a concrete repair material. The best repair products will be able to withstand the specific conditions that are unique to your project. They will also have low viscosity to allow them to flow easily into narrow cracks without the need for routing. This is particularly useful for concrete restoration projects that are time-sensitive.
Stitching
A concrete repair that utilizes carbon fiber stitching to strengthen and stabilize cracked or deteriorated concrete. Stitching is a cost effective alternative to epoxy grout filling and a more structurally sound option for repairing structural cracks. Stitching involves drilling holes on both sides of a crack, then placing carbon fiber laminates in the holes and adhering them with a low viscosity polyurethane bonding system. The stitching prevents the crack from expanding or further deteriorating.
Before applying the new concrete or patch mix, it is necessary to clean the repair area thoroughly to remove dirt, dust, loose aggregate, oil, grease and other materials that may interfere with the proper bonding of the repair material. If possible, it is preferred that the surface to be repaired be dry. Often concrete repairs must be made quickly, so it is difficult to wait for mother nature to dry the area. A concrete cleaning spray or power washer may be used to speed up the process.
It is also important to determine the cause of the deterioration before selecting a concrete repair method. A thorough inspection including a visual inspection, destructive and nondestructive testing should be performed. The results of this evaluation will allow the appropriate concrete repair method to be selected.
When using a traditional cementitious repair material, it is recommended that the depth of the patch be kept to a minimum. This will help reduce the heat generated during curing that can cause spalling of the existing concrete. In addition, a diversion system or an external waterproofing may be required to prevent water from entering the concrete during repair.
Concrete patching can be accomplished with either conventional dry mix or ready-mix concrete. Both of these methods require a good amount of hand mixing and require the use of a margin trowel to eliminate air bubbles and obtain a smooth finish. It is essential to achieve proper concrete consolidation around dowel bars and along the patch perimeter. If the concrete is too loose, it will chip during lifting and cause damage to the existing concrete.
For larger concrete patches, a concrete truck can be called to deliver the necessary batch of concrete. The concrete is then placed into the repair area with a margin trowel or gloved hands. Project Tip: For very large patch areas, it is sometimes faster and easier to mix the concrete by hand rather than build a form for it. This is especially true when using fast setting products.
Bonding
Concrete repair involves bringing in new concrete to replace existing, damaged or deteriorated sections of a structure. Whether the replacement concrete is placed in-place or as precast slabs, a good bond with the base concrete is critical to the long term durability of the repair. This requires the use of a suitable concrete repair material with a low w/c ratio and a high percentage of coarse aggregate to reduce shrinkage cracking.
Surface preparation and concrete removal practices are also important in concrete repair. Chiseling the old concrete to a level appropriate for placement of the replacement concrete is usually required in order to expose sound concrete. This will reduce the amount of time required for concrete repairs and also ensure that the replacement concrete bonds properly with the remaining concrete.
A bonding agent is normally used to prepare the surface of the existing concrete for the application of a concrete repair product. Some bonding agents are acid washing products which roughen the surface of concrete, while others are a latex emulsion with portland cement or epoxy resins. Some bonding agents are not compatible with certain types of concrete, so a careful assessment of the repair is needed to determine which type of bonding agent will be best suited for a specific job.
After a bonding agent has been applied, the existing concrete surface should be cleaned with a degreaser or a chemical cleaner to remove any contaminants which might prevent proper adhesion between the existing and replacement concrete. The concrete should then be protected from windy, dry or freezing conditions while the concrete repair material is in a plastic state. This protection will help to prevent moisture loss, drying shrinkage cracking or curling.
Once the concrete is in place, the strength of the concrete should be tested to ensure that it will withstand the loads that the concrete will be subjected to. This is often done using a rebound test which measures how far the concrete will rebound after being struck by an impact hammer. It is important to note that the test results may vary depending on the condition of the concrete and the equipment used for testing. The location of the repair will also have an impact on the types of materials that can be used. For example, some repair materials are odorous, toxic or combustible and cannot be used in certain locations.
Repairing Cracks
Depending on the cause of the cracking and the type of repair material used, there are several different methods for repairing concrete cracks. Stitching is a non-disruptive method that involves drilling an entry and exit hole across the crack and running a series of U-shaped metallic staples (or dowels) through them, anchoring them to the adjacent concrete with epoxy or grout. Stitching repairs can be made to new and old concrete and can be very cost-effective.
Before beginning any concrete crack repair, it is important to identify what caused the damage and to clean away any loose debris in or around the crack. Also, the cracks should be clean and dry so that the filler or patching product can bond well.
In many cases, it is best to leave the concrete crack repair work to professionals who have the expertise and equipment to ensure that the repair is done correctly. They can also provide guidance on preventative maintenance, to reduce the likelihood of future repairs.
A professional contractor can make a permanent repair by cutting out the damaged section and replacing it with fresh concrete. This is often a more economical choice than replacing the entire slab and is especially effective for small to medium-sized cracks.
If a structural engineer determines that the crack is caused by an unstable foundation, it may be possible to reinforce the area with steel. A steel-reinforced concrete (SRC) panel can be inserted into the existing cracked concrete to support it and prevent further movement.
Using a hammer and masonry chisel, it is possible to chisel out the crack to create a backward-angled cut. This widens the base of the crack and helps it to better adhere to the surrounding concrete.
Before applying the concrete crack repair, it is a good idea to use a foam backer rod to create a stable base for the filler or patching material. Backer rod is available in a variety of diameters; choose a size that is slightly larger than the width of the crack.
After the crack is cleaned and prepared, a latex or polyurethane-based concrete repair product can be applied. Latex products are easy to clean and generally last for a couple of years, while polyurethane-based products require acetone for cleaning but offer superior durability and longevity.
