Spalling of Concrete Repair – What is Spall Repair?

This article is about Spall Repair Procedure and Spalling of Concrete Repair. Spall repair refers to the process of repairing damaged or deteriorated concrete surfaces by removing the damaged material and replacing it with new concrete. Spalling can occur due to various reasons such as freeze-thaw cycles, corrosion of reinforcing steel, or mechanical damage. Here are some common spall repair procedures:

1. Surface Preparation: The first step in spall repair is to prepare the surface by cleaning it thoroughly. This involves removing any loose or deteriorated concrete, dust, oil, or other contaminants that may hinder the bonding of the new concrete to the existing surface. A wire brush or abrasive blasting can be used for this purpose.
2. Bonding Agent Application: A bonding agent is applied to the prepared surface to improve the bond between the old and new concrete. The bonding agent can be in the form of an epoxy or latex-based material.
3. Placement of New Concrete: Once the bonding agent is applied, the new concrete is placed onto the surface using a trowel or other tools. The new concrete should be leveled and smoothed to match the surrounding surface.
4. Finishing: The surface of the new concrete should be finished to match the surrounding surface. This can be done by using a trowel, sponge, or other finishing tools.
5. Curing: The new concrete should be allowed to cure for a minimum of 28 days to achieve its maximum strength. Curing can be done by keeping the surface moist or by using a curing compound.

What is Spall Repair?

Spall repair refers to the process of repairing concrete surfaces that have chipped or broken away due to age, weathering, or other types of damage. The repair is typically done by filling in the damaged area with new concrete or a specialized repair material.

When it comes to repairing an area, it is crucial to start with a clean surface. Once the area has been thoroughly cleaned, it should also be completely dry and free of any dust, oil, dirt, or other debris. This ensures that the repair process can be carried out effectively and that the repaired area will be able to withstand future wear and tear.

To begin the repair process, it is generally necessary to mix the repair materials in a small drum or mortar mixer. While some materials come premixed, others may need to have aggregate added to them to achieve the desired consistency. It is important to note that the maximum recommended size for any added aggregate should be no larger than 3/8 inch or 10 millimeters.

Once the repair materials have been mixed, it is necessary to consolidate them by tamping the material down. If possible, vibration may also be used to further consolidate the material. After consolidation, the surface should be carefully worked to match the surrounding finish as closely as possible. This attention to detail is crucial for achieving a seamless and professional repair that will last for years to come.

Read Also: Equipment List used for Concrete Crack Repair

Spall Repair Procedure

Joint Filler

When repairing a spalled area that is adjacent to an expansion joint or a crack, it is important to use a joint filler. This will prevent the repair material from getting into the joint and causing further damage, and it will also help to retain the shape of the joint. If the spall is located next to a crack, the crack must be treated as an expansion joint. It is crucial not to bridge any cracks or expansion joints during the repair process. The crack should be formed up just like an expansion joint to ensure that the joint filler can be applied correctly.

The joint filler used in this process should have the same width as the existing joint or crack. It should also be long enough to cover the spall area and deep enough to cover the full depth of the spall. This will ensure that the joint filler provides the necessary support to prevent any further damage to the area. By following these guidelines, the repair process can be completed effectively, and the repaired area will remain structurally sound.

NOTE: Application of bonding agent to the concrete surface. Note the joint filler bordering the repair area

Bonding Agents

To enhance the bond between patch repair materials and the surface being repaired, bonding agents are commonly used. For repairs utilizing Portland cement concrete (PCC), it is necessary to apply a thin layer of bonding agent. However, for repairs involving rapid setting or polymer concrete, it is recommended to follow the manufacturer’s instructions regarding the use of bonding agents.

In PCC repairs, the bonding grout consists of a mixture of one part Portland cement to one part sand with a water-to-cement ratio of less than 0.45. To ensure proper adhesion with the repair surface, the bonding agent must be brushed into any crevices and cracks. If proprietary repair materials are used, it is important to follow the manufacturer’s instructions closely, as they may require a specific bonding agent.

During application, the entire repair surface should be lightly coated or sprayed with the bonding agent, and the repair material should be placed when the bonding agent has reached a tacky consistency. If the bonding agent is dripping through small openings where the joint filler meets the bottom of the spall recess, it may be necessary to apply a small bead of caulk to prevent dripping.

Mixing and Placing

The process of mixing and placing spall repair materials can be challenging due to the wide variety of materials available. To ensure a quality repair job, it is important to follow good practices. This includes placing the repair material at pavement temperatures between 55 and 90 degrees Fahrenheit (13 to 32 degrees Celsius). If water is required, it should be clean and fresh, and added in the correct amount before thoroughly mixing the material.

Hand mixing can be a time-consuming process, and there is a tendency to add more water than necessary to make it easier. It is important to strictly follow the manufacturer’s recommendations for mixing and curing the materials to ensure a high-quality patching job. Repair materials should not be placed at temperatures below 40 degrees Fahrenheit (4 degrees Celsius), and if it is necessary to work at temperatures below 55 degrees Fahrenheit (13 degrees Celsius), special insulation and longer cure times should be used.

When working in summer, it is best to place repair materials in the morning when pavement temperatures are lower. In winter, afternoons are the ideal time to work. By following these guidelines, spall repair jobs can be completed to a high standard, and the repaired pavement will be able to withstand the rigors of traffic and weather.

Read Also: Plastering Concrete Surfaces – Methods and Procedure

Consolidation

When repairing a surface, it’s important to make sure that the repair material is properly consolidated to remove any trapped air. This is especially true for cementations and polymer concrete materials, which may require some form of consolidation, such as tamping or vibration. For smaller repairs, it’s recommended to use vibrators with a small head or vibratory screeds. It’s important to avoid using grate tampers as they may not be suitable for the job.

Once the repair material has been consolidated, it’s necessary to finish it to match the surrounding pavement. A completed patch should look seamless and blend in with the existing surface. In some cases, spall repairs may need to be conducted on both sides of an expansion joint, and joint filler should be used to separate the repair from the joint.

1.Consolidation of the repair material by vibration(above)

2.Finishing the patch surface(above)

3. A completed spall repair that bridges an expansion joint(above)

Curing

Proper curing is of utmost importance when it comes to partial-depth repairs, especially since the repair area has a larger surface-area-to-volume ratio compared to a full-depth repair. This means that bond strength develops much slower than compressive strength, making rapid water loss from the surface due to high temperature, low humidity, and/or windy conditions a real concern. If not addressed, this could lead to severe shrinkage cracking on the surface.

To ensure proper curing, it is recommended to cover the patched area with two layers of presaturated burlap, followed by clean polyethylene sheeting. The burlap and sheeting should then be covered with weighted plywood or form board, with all cover layers extending 12 inches (300 millimeters) beyond the outline of the patch. These covers should be removed daily, the burlap resaturated, and the covers replaced for at least 7 days.

It is important to note that fresh PCC should be covered as soon as possible after finishing the surface. For rapid-setting concretes, special curing procedures must be followed to prevent excessive shrinkage cracking. These materials harden rapidly, and severe plastic shrinkage cracking may develop on the surface if they dry too fast. To avoid this, it is important to follow the manufacturer’s recommendations for curing of proprietary concretes.

Resealing

Once the patch has fully cured, the next and final step in the repair process is to replace the sealant in order to maintain the integrity of the joint or crack. It is important to note that the resealing of the joint or crack should not begin until the concrete has completely finished curing.

To carry out the joint sealing process, the joint or crack adjacent to the spall is sawed out to the same width as the existing joint or crack, using either a concrete saw, router, or hand saw. It is also necessary to remove the joint filler either by hand or by sawing.

Next, the sides of the saw cuts are sandblasted and air blasted with compressed air, and then washed with high-pressure water. This is done in order to prepare a suitable surface for optimal adhesion of the sealant. In addition, the area surrounding the repair must be thoroughly swept with a vacuum broom to ensure the removal of all debris.

Once the area has been cleaned, a backer rod is installed in the joint or crack recess to help support the sealant. This is an essential step in the process that helps to ensure the effectiveness of the sealant.

Placing Sealant

When it comes to placing sealant, the technique is similar to that used for crack sealants. It’s important to start from the bottom and work your way up. In addition, the sealant should be applied in one smooth stroke that covers the entire length of the joint or crack, if possible. This approach may not always be feasible, but it is recommended whenever practical.

The placement of sealant is an important step in ensuring the effectiveness of the seal. By starting at the bottom, you can ensure that the sealant fills the entire gap and does not leave any spaces or gaps that could allow water or other contaminants to penetrate the joint. Applying the sealant in a single stroke helps to ensure a uniform seal that is less likely to fail over time.

While it may not always be possible to apply sealant in a single stroke, especially in cases where the joint or crack is very long, it is still recommended to strive for this approach whenever practical. By following these guidelines, you can increase the likelihood of a successful seal that will provide long-lasting protection for the surface or structure in question.

Cleanup

When the repair work has been finished, it is important to ensure that all equipment used during the process is appropriately taken care of. This involves cleaning and lubricating the tools if required. By doing so, any dirt or grime accumulated during the repair can be removed, and the tools can be maintained in a good condition for future use.

Proper storage of the equipment is also a vital step. It is essential to ensure that the tools are stored in a safe and secure location, where they are not at risk of being damaged or misplaced. Keeping the equipment in an organized manner can also help in locating the tools easily when they are needed for the next repair operation.

By following these steps, it is possible to ensure that the equipment is well-maintained and ready to be used for the next repair task. This not only saves time and effort but also helps in avoiding any unforeseen problems that may arise due to the use of poorly maintained tools. Overall, proper care and maintenance of equipment after a repair operation can go a long way in ensuring efficient and effective repair work in the future.

Read Also: Equipment List used for Concrete Crack Repair

FAQS ABOUT SPALL REPAIR

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