Concrete is one of the most durable construction materials available and can provide decades of reliable performance if it’s installed properly. However, time, weather and wear will eventually take their toll on the material and necessitate the occasional repair.
That’s where the pavement professionals come in. In many cases, concrete pavement can be repaired and restored, but only if the damage is resolved in a timely manner. The longer the delay, the more likely the concrete will require more intensive (and therefore more expensive) fixes.
Here, we’ll review the signs of concrete damage and what a professional Houston paving team can do to resolve them.
Cracking and Crazing: Proper Curing, Fillers and Epoxy Injections
To some extent, concrete cracks are impossible to avoid. There are a variety of reasons why concrete may crack, and modest, isolated cracking is typically harmless. However, some cracks require prompt repair to prevent them from spreading and causing structural issues. When assessing concrete cracks, pavement contractors are interested in the following:
- The width of the crack – The wider the crack, the more challenging the repair. With fine cracks (less than .04 inches wide), there’s enough contact between aggregate to maintain vertical alignment in the slab. Wider cracks don’t. This will partially determine which repair method to utilize.
- Whether the crack is active or dormant – Active cracks are still in the process of spreading and widening. Dormant cracks are not. Whether a crack is active or not depends on where the crack is located and what environmental conditions are present. Certain sealing methods cannot be used with active cracks, including epoxy injections.
- If the crack threatens the concrete’s structural integrity – The majority of cracks do not threaten the concrete’s integrity, but there are instances where cracks are extensive and deep enough to destabilize the material. If there are structural concerns present, comprehensive repairs will be needed to restore strength and durability.
Depending on the above, the following crack repair methods may be recommended:
- Routing and filling – During routing and filling repair, a groove is routed into the concrete that follows the crack. This creates a channel that’s slightly wider than the existing crack and provides a uniform surface for the crack filler. Once the groove is cut out, the filler is applied and allowed to dry.
- Epoxy injection – Epoxy injections are one of the few repair methods that can improve concrete’s structural strength. First, the crack is cap-sealed with the epoxy, then holes are drilled along the crack’s length. The epoxy injectors are positioned in these drilled-out holes and epoxy is injected into the concrete. High pressures, around 5,000 psi, are achievable with epoxy injection, which is what provides a measure of structural stability and strength.
- Patching – If cracks are dormant, patching them may be sufficient for repair purposes. This involves spreading a new mix of concrete over the pavement’s surface and into the cracks. It’s important that any subsurface issues with the concrete be resolved prior to patching, or the cracks will soon reappear.
If cracking is excessive and cannot be resolved with the above, then overlaying a new concrete surface may be recommended. Concrete overlays can be installed in a range of thicknesses and restore the surface’s durability and appearance.
Blistering and Delamination: Resurfacing and Patching
Blistering is a common surface flaw and is the result of air or water becoming trapped just below the concrete’s seal. In most cases, this occurs during installation if concrete isn’t properly vibrated or the surface isn’t properly finished. Blisters can also form due to a poor concrete mix or concrete that is poured too thick.
Delamination occurs when the top layer of concrete effectively separates from the rest of the pavement. It can result from the same installation or mixing mistakes that cause blisters.
No matter the cause, it’s difficult to spot-repair blisters or delamination. Resurfacing with a concrete overlay may be the only practical option, especially if the issue is widespread. First, the pavement crew will verify that there aren’t underlying issues causing the cracks. If there are, they must be corrected first or the overlay will fail quickly.
Assuming the damage is only surface deep, the overlay concrete is mixed and applied in thin layers to ensure each layer dries thoroughly. For smaller jobs, this can be done with a trowel. For larger commercial projects, though, the pavement crew may use a hopper.
Surface Discoloration: Cleaning and Sealing
Discoloration can be part of the natural aging process for concrete, but it’s often the result of poor curing or mixing practices. Discoloration can also be caused by variances in water content across the pavement’s surface, which may be a mixing or troweling issue.
Discoloration rarely points to a structural problem, but discolored areas can make a property appear old or run down. For experienced professionals, the fix is simple. The project may only involve a powered rinse. If that’s not enough, pavement crews have a variety of cleaning products that can attack certain types of discoloration. Mold and mildew can be cleaned with bleach, while an acid rinse can remove metal deposits or dark spots.
Once cleaned, the pavement team will apply a sealer that can help color the concrete and provide the desired look. Sealer also protects the pavement’s surface from damage and future discoloration.
Professionals typically use sprayers to apply concrete sealer, as they can cover a larger area efficiently.
Popouts: Remove the Compromised Concrete and Replace it With New Mix
Popouts are cone-shaped chunks of concrete that have been “squeezed” out of the pavement. Think of it like a concrete pimple popping. There may be broken pieces of aggregate in the resulting hole. Popouts range in size and aren’t a major concern if they’re on the smaller end. Large popouts can cause unsafe driving conditions and expose the concrete to further damage, though.
In this instance, concrete repair consists of the following:
- Removing the damaged pavement – First, the concrete ringing the inside surface of the popout is first removed. This can be done with sawcutting or drilling. The goal is to create a smooth interior surface for the new mix to adhere to.
- Placing a bonding agent – And to help that new mix adhere, a bonding agent is first applied to the inside surfaces. Think of it like concrete glue.
- Filling the hole with new mix – Once the bonding agent is in place, the new concrete mix is used to fill the popout. It’s then given time to cure and will be ready to bear weight within 48 hours.
If there are too many popouts to fill individually, installing an overlay can improve surface strength and appearance over a larger area.
Spalling: Isolate the Damage and Apply New Concrete
Spalling is also a surface defect, but it extends deeper than the typical popout. The same rules apply, though. While many spalls are too small to cause structural or safety issues, they can increase the chances of early pavement failure. Spalls are caused by excessive expansion or pressure inside the concrete, poor joint placement, or corroded steel reinforcement. Heavy impact can also produce spalls.
The spall repair process is similar to fixing popouts. Any underlying issues, such as failed steel reinforcement, are corrected first. Then, the damaged pavement is cut or drilled out. The resulting hole is coated with bonding agent to enhance adhesion, and then new concrete mix is poured into the hole and allowed to cure.
Concrete is Durable, But a Challenge to Repair. That’s Why Commercial Properties Call on the Houston Experts
Concrete pavement is extremely durable, which is why it is used so often. But when damage does occur, fixing it can be tough for property owners. Concrete repairs require extensive equipment and manpower resources – not to mention experience.
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