Common concrete crack repair methods

Concrete cracks are a common issue in buildings and structures. They often occur due to factors like temperature changes, foundation settlement, external loads, or environmental conditions. While these cracks may appear small at first, they can widen over time, potentially compromising the structure’s stability and creating safety risks. For this reason, it's important to repair concrete cracks promptly. This article provides an overview of simple crack repair methods, supported by real-world case studies to help explain each technique.
1. Common Concrete Crack Repair Methods

Cement Mortar Repair
Cement mortar repair is one of the most commonly used and simplest methods for fixing cracks, especially when the cracks are shallow and don't affect the load-bearing capacity of the structure. The process involves cleaning the crack area to remove debris and dirt, then filling the crack with a suitable mixture of cement mortar. Once filled, the surface is smoothed to ensure the repair is level with the surrounding concrete. This method is affordable and effective for minor surface cracks.
Epoxy Resin Repair
Epoxy resin repair is typically used for deeper cracks, particularly structural cracks that could impact the overall strength of the building. Epoxy resins have excellent bonding strength and durability, making them ideal for restoring the structural integrity of the cracked area. The repair involves cleaning the crack thoroughly and using an injection system to inject the epoxy resin deep into the crack. Once injected, the resin penetrates deeply and hardens, bonding tightly to the surrounding concrete and restoring the structure’s strength.
Polyurethane Foam Injection
Polyurethane foam injection is particularly suitable for cracks in wet environments, such as basements or underground structures. The advantage of polyurethane foam is its ability to expand and fill larger cracks, while also providing excellent waterproofing properties. The repair process involves injecting the foam into the crack with specialized equipment. As the foam expands, it fills the crack completely, and once it cures, it forms a solid seal that prevents water from seeping through, offering long-lasting protection against leaks.
2. Common Repair Products

Epoxy Resin
Epoxy resin is a popular choice for repairing cracks, especially structural ones. It is known for its strong adhesion, durability, and high compressive strength, making it ideal for restoring the original strength of concrete. Epoxy resin forms a hard, permanent bond that helps prevent further crack growth. Well-known brands like Alpha, Wills, and Leiman offer easy-to-use epoxy resins that don’t shrink after curing, ensuring a lasting and reliable repair. These resins are particularly useful for deep, structural cracks and help maintain the integrity of the structure.
Cement-Based Repair Mortar
Cement-based repair mortar is commonly used for surface crack repairs. It is an affordable and easy-to-apply material, making it a great choice for smaller cracks or less critical repairs, such as those found in residential renovations. Cement-based mortars provide good adhesion to concrete and are resistant to water, helping prevent moisture from penetrating and causing further damage. This material is often chosen for its simplicity and cost-effectiveness in addressing minor cracks.
Polyurethane Injection Grout
Polyurethane injection grout is a high-performance repair material known for its excellent waterproofing capabilities. It is particularly effective for cracks in underground spaces, tunnels, basements, or other areas exposed to high moisture. The grout expands when injected into cracks, filling them completely and bonding tightly to the surrounding concrete. Once cured, it forms a flexible, waterproof barrier that prevents water infiltration and provides a long-lasting seal, making it an ideal solution for environments where moisture control is critical.
3. Case Studies

Case 1: Repair of cracks in a basement: A basement was exposed to water for a long time, and many cracks appeared, especially in the lower part of the wall, which were more numerous and wider, causing serious water leakage.
Repair Method: The project team decided to use polyurethane foam injection to repair the cracks. First, the cracks were cleaned of debris and moisture to ensure proper adhesion. Polyurethane foam was then injected into the cracks, where it expanded rapidly to fill the entire gap. The foam created a waterproof seal, effectively solving the water leakage problem. After the repair, the basement remained dry, and no further cracks or leaks occurred.
Case 2: Factory Floor Crack Repair: In a factory, several cracks appeared in the concrete floor, mainly due to temperature fluctuations and the frequent operation of heavy machinery. These cracks affected the smoothness of the floor, impacting the operation of equipment.
Repair Method:Since the cracks were relatively shallow and did not compromise the structural integrity of the floor, the engineers chose cement mortar repair. The crack areas were cleaned, and cement mortar was mixed and applied to fill the cracks. After smoothing the surface, the floor was restored to its original level. Once repaired, the factory floor was smooth again, and equipment operations were not disrupted.
Case 3: Wall Crack Repair in a Residential Building: A residential building had cracks in its external walls, ranging from 1 to 2 millimeters in width. These cracks were primarily caused by the settlement of the building. While the cracks were small, they allowed water to infiltrate, worsening the issue.
Repair Method:The team decided to use epoxy resin injection to repair the cracks. Small holes were drilled on either side of the cracks, and injection nozzles were installed. Epoxy resin was injected into the cracks, filling them completely. Once the resin cured, it formed a strong bond, effectively sealing the cracks and preventing further water infiltration. After the repair, the walls no longer leaked, and the cracks were successfully sealed.
4. Conclusion

There are several methods available for repairing concrete cracks, ranging from simple solutions like cement mortar repairs to more advanced techniques such as epoxy resin injections. Each method is suited for different types of cracks and specific situations. Choosing the appropriate repair method and product is essential for effectively addressing the issues caused by cracks and extending the life of the structure.
This article introduces three common concrete crack repair methods - cement mortar repair, epoxy resin injection and polyurethane foam injection, and uses practical cases to demonstrate the application of these methods in real-world scenarios. By understanding the advantages and appropriate uses of each repair method, you can make an informed decision on how to best address concrete cracks in your building or structure.