Cracks in concrete structures can compromise their strength, durability, and appearance. As a facilities engineer, you need to know how to effectively repair them and prevent further damage. In this article, you will learn about the causes, types, and methods of concrete crack repair.
Concrete cracks can result from various factors, such as shrinkage, thermal expansion and contraction, moisture, loading, corrosion, and chemical attacks. Some of these factors are inherent to the material properties and curing process of concrete, while others are related to the external environment and service conditions. Understanding the causes of concrete cracks can help you choose the appropriate repair strategy and materials.
Shrinkage: Concrete shrinks when it dries, making tiny cracks. Settlement: If the ground under the concrete is not even, it can cause cracks. Too Much Weight: Heavy things on the concrete or strong hits can also make cracks. Chemicals: Sometimes, chemicals in the concrete or around it can make cracks. Hot and Cold: Big changes in temperature can make the concrete expand and shrink, causing cracks.
It is an understood fact that you will deal with concrete crack problems during the life of your concrete structures and surfaces. Depending on the cause of cracking and its nature, several methods such as epoxy injection, routing and sealing, stitching, conventional reinforcement, drilling and plugging, gravity filling, grouting, polymer impregnation can be used to repair the cracks effectively.
Concrete cracks can be classified into different types according to their shape, size, orientation, and location. Plastic shrinkage cracks are fine, shallow, and irregular cracks that form on the surface of fresh concrete due to rapid evaporation of water. Drying shrinkage cracks are deeper, wider, and more uniform cracks that develop in hardened concrete due to loss of moisture and volume. Thermal cracks are caused by temperature changes that induce stress and strain in concrete. Structural cracks are caused by excessive loading, settlement, or vibration that exceed the tensile strength of concrete. Corrosion-induced cracks occur when steel reinforcement expands due to rusting, which creates pressure and cracks in the surrounding concrete. Chemical-induced cracks result from the reaction of concrete with aggressive substances such as acids, sulfates, or chlorides that degrade its integrity and durability.
Small Cracks: These are thin and not deep, usually because of shrinking. Big Cracks: These are wider and go deeper, making the concrete weaker. Surface Cracks: Fine lines on the surface because of how the concrete was made or finished. Uneven Cracks: Cracks caused by the ground under the concrete not being flat or packed well.
Concrete crack repair methods can be divided into two categories: active and passive. Active methods, such as epoxy injection, routing and sealing, stitching, grouting, and reinforcing, aim to seal the cracks and restore the structural integrity of concrete. Passive methods, like painting, plastering, and overlaying, focus on improving the appearance and protecting the concrete from further deterioration. Epoxy injection involves injecting a low-viscosity epoxy resin into the cracks under pressure to fill the voids and bond the concrete together. Routing and sealing involves cutting a groove along the crack and filling it with a flexible sealant. Stitching requires drilling holes across the crack and inserting metal staples or bars that hold the concrete together. Grouting involves pumping a cementitious or chemical grout into the cracks which hardens and seals them. Reinforcing involves adding external or internal reinforcement such as steel plates, carbon fiber sheets, or steel rods to strengthen the concrete and prevent further cracking. Painting involves applying a thin layer of paint or coating over the cracks to improve aesthetics and provide some protection from moisture and chemicals. Plastering involves applying a thick layer of mortar or plaster over the cracks which covers them and provides a smooth surface. Overlaying involves applying a new layer of concrete or other material over the existing cracked concrete to conceal them and provide a new surface.
Injecting Epoxy, also A new idea could be using strong carbon fiber along with epoxy to make it even stronger. Injecting Polyurethane: Similar to epoxy, this involves using a special liquid to fill and seal the cracks. Making Cracks Bigger: Sometimes, we make the cracks wider with tools and then fill them up with special stuff to make them strong again. Using Carbon Fiber: When cracks are big and the concrete needs more strength, we can stick carbon fiber on them to make them stronger. We put strips of carbon fiber on the cracks and stick them well. A new way could be using carbon fiber sheets with sensors that tell us if the cracks are getting worse or not.