By Jeff Blank
The type of damage you see on your concrete is often a clue as to how it occurred in the first place. Proper diagnosing of the problem can help you determine how best to fix it, and how soon you need to address it.
First, let’s look at four common types of damage.
- Cracks: Cracks are inevitable, and they can start appearing within two weeks of the pad being poured if not enough control joints were factored in. Hairline cracks are OK. They may be a bit unsightly, but they’re typically not going to lead to any bigger problems.
When should you be concerned about a crack? Generally speaking, you might want to intervene by repairing, resurfacing or replacing if:
– The crack seems to allow water to get underneath the pad, which will worsen the damage.
– The crack is becoming a safety hazard. Did you know that if there’s a change in grade of greater than one-quarter inch the Americans with Disabilities Act considers it a trip hazard?
– The crack looks bad and is not portraying the kind of image you want for your business.
- Spalling: Spalling, or pitting, is the chipping or flaking that occurs on the concrete’s surface when it’s exposed to freeze-thaw cycles or it’s the victim of improper mixing. Freeze-thaw occurs when water gets into the pores, and then freezes and expands. Moisture can expand up to 9 percent of its previous volume when frozen, so when it thaws, moisture under the top layer of rigid concrete it can create pressure that leads to spalling.
The proper mix at the time of pouring, including an appropriate amount of air entrapment to allow for water expansion, can help minimize incidences of spalling. While it’s unsightly, spalling in and of itself is not indicative of a larger problem, such as a failing sub-base. It can typically be resurfaced and sealed to address the issue.
- Settlement: When voids form under a concrete pad, the concrete tends to crack, break, and settle into the void. The result is an uneven and unstable surface that likely requires quick action before even larger damage can occur.
Voids typically form through some type of issue with the soil, such as it being loosely compacted at the time of pouring, there being a severe drying and shrinking of the soil, or the occurrence of an underground water leak that causes a washout of a portion of the soil.
- Lifting: Lifting is also a possible consequence of freeze-thaw cycles. You see it commonly on sidewalks when nearby tree roots grow over time and cause a pad to lift. Frozen moisture under the surface can also cause larger sections of a concrete slab to lift at the joints, allowing for even more water and debris to enter underneath and cause greater damage.
Severely lifted pads deserve immediate attention as they can be considered a safety hazard for pedestrians and individuals in wheelchairs, and can sometimes even cause damage to vehicles driving over it.
Concrete Improves With Age
Concrete is very strong, and it gets stronger over time. The age of your concrete may actually work in your favor because older concrete has settled and already passed the “good concrete mix” test of time.
Pitting and signs of wear on the surface of concrete that is still structurally sound underneath typically means the concrete can be resurfaced. An experienced professional can examine your pad and determine the sub-base’s structural integrity.
The bias in the industry is to quickly jump to replacing concrete before exploring other alternatives, yet in a vast majority of cases, concrete damage can be restored. Restoring essentially involves maintaining the already settled and still viable sub-base, and applying an engineered epoxy concrete alternative as the repair or new top layer.
When trying to decide between replacement and resurfacing, consider this:
- Disruption: Tearing out concrete and replacing it with new involves jackhammers, dump trucks, cement mixers, backhoes, landscaping repairs, fumes, loud noises, and possible difficulty for customers and employees to access your facility. Resurfacing is a much simpler, less-invasive job, and re-uses your existing sub-base to eliminate the need for much heavy equipment.
- Downtime: Removing and re-pouring concrete can be a 10-day project, particularly if it needs to handle vehicle traffic. Resurfacing can typically be done start-to-finish in one to two days.
- The Unknown: Whenever you rip out old concrete, you run the risk of unearthing larger problems with the foundation, plumbing, or underground utilities that could add costs and further delays to the project’s completion. Resurfacing limits your project to the surface layer of concrete, leaving below-ground complications untouched.
- Expense: Resurfacing with an epoxy resin overlay may be a similar price per cubic foot as concrete, but when you factor in its greater strength and durability, superior sealing properties, flexibility in color, chemical-resistance, and quicker turnaround time, it can be a greater value.
Getting a proper diagnosis of the problem is the first step before determining the best course of action. Don’t jump too quickly to replacing your concrete, as a much easier, concrete-alternative solution could be a better option.
With more than 30 years of experience in the construction materials industry, Jeff Blank is vice president of Research & Development and Purchasing at SR Products, an affiliate of Simon Roofing that manufactures and develops the proprietary coatings used in Simon Roofing’s building solutions.