Crack the Code – Identifying and Repairing Concrete Issues
Concrete is an incredibly durable material that can last for hundreds of years and holds up well against weather conditions, abrasion and chemicals. However, despite its durability and longevity, there are some situations and conditions under which it begins to crack.
Identifying the different types of cracks in concrete can help you determine the cause and take appropriate steps for repair.
Damaged Edges
Concrete is an excellent material for building slabs and structures, but it is more vulnerable to damage at corners and edges. This can be due to improper construction or weathering. Concrete that is cracked and crumbling at the edges may not be structurally sound, so it should be repaired immediately.
Uneven or sunken concrete surfaces pose tripping hazards for residents and visitors, and may indicate underlying soil issues or foundation problems. Repairing these issues promptly prevents more extensive damage and costly replacements.
Cincinnati Concrete Contractors, spalling is a serious problem that exposes coarse aggregate under the concrete surface and can lead to structural weakness in the entire slab. This can be caused by chemical reactions, freeze-thaw cycles, or natural aging, and it is a clear sign that the concrete needs to be replaced. The good news is that this type of damage can be easily repaired with a high-performance concrete patch mixture such as Sakrete Top ‘N Bond.’
Cracked Slabs
Depending on their size, location and appearance, cracks in concrete slabs can be either cosmetic or structural. While hairline cracks in the surface of a slab rarely impair its strength, they should be repaired if they widen over time, pose a safety risk or collect dirt and debris.
Narrow cracks can be filled by “keying” them with foam backer rod before applying concrete repair materials. This technique adds a mechanical bond to the concrete while also helping to prevent further cracking. It is also a good idea to undercut the sides of wide cracks to give them an inverted V shape, which helps the repair material key into the concrete to create a stronger mechanical and chemical bond.
Larger cracks in slabs may be due to settlement, poorly compacted soil or a lack of steel reinforcement. A qualified and licensed professional should be consulted to determine the severity of the cracks, and whether a solution is required.
Cracked Joints
Cracks in concrete joints can result in trip hazards and injuries for your guests and employees. Even non-structural cracks that are repaired quickly can improve safety outcomes.
When the tensile stress on concrete exceeds its ductility, it begins to crack. This happens in both plastic and hardened concrete. To avoid uncontrolled cracking, the slab should be designed with expansion and contraction joints.
Contraction joints are usually created either by jointing tools during the pour or by sawing after the concrete is set with a wet-cut saw. They control cracking that develops due to restrained shrinkage, loads and other stresses.
Expansion joints are gaps between two concrete slabs that allow the concrete to expand and contract with daily temperature variations without restricting movement. The layout of these joints is typically the responsibility of the slab designer but when a project is not specified, the concrete contractor becomes the designer. This helps ensure that the expansion and contraction joints are properly spaced.
Cracked Surface
Concrete surfaces crack, and while some of them aren’t a cause for concern (hairline cracks that form immediately after concrete pouring) others pose a risk to the strength and durability of a structure. Luckily, you can prevent and repair cracked surfaces with the right maintenance techniques.
First, start by cleaning the crack. This helps the filling material to bond properly and will eliminate any leftover debris that could compromise your repair.
It’s also important to moisten the surface of the crack before you apply the filling material. This helps prevent the crack from re-opening once the surface of the concrete expands and contracts naturally.
Once the crack is clean and moistened, you can fill it with a ready-mixed concrete patch. Choose a product that resists oil, grease, and deicing salt and spread the patch with a putty knife or broad knife.