Concrete – the #1 most commonly used building material in the world – is not just cement, despite the popular misconception. Cement is actually just the binding agent that holds together the water and aggregate. In other words, cement is an ingredient in concrete, and does not have the same standalone properties as concrete.
While it’s durability is undebatable, concrete will crack. That’s right, we said it WILL crack – not might, or can, or could. Contractors attempt to control cracking by placing cuts, or joints, every 10 – 12 feet in flatwork. These joints provide a template for any reasonable/expected cracking to follow. You might say that concrete joints perform a similar function to the perforations in a graham cracker. While the graham cracker might not break exactly on the line, breaks will usually stick pretty close, and prevent the entire cracker from crumbling.
However, concrete is a bit more complicated than a graham cracker, and all concrete cracks are NOT created equally. Some types of cracking are primarily cosmetic, and need little, if any, repair. Meanwhile, others may require inspection, monitoring, and/or repair by an experienced professional.
If you’re worried about cracks in your concrete, then you need to ….
1- Measure the Concrete Crack
When you begin to notice cracking in your concrete structure, the first thing you need to is measure the crack’s width, depth, and length to the best of your ability. According to the South Carolina Residential Construction Standards, concrete flatwork may contain cracks up to 5/16” in width– or vertical displacement– before they require some type of patchwork or repairs.
2- Identify the Source of Concrete Cracks
By taking note of the specifications of the cracks in your slab, or concrete structure, you’ve likely got a pretty good idea of whether this is a hairline crack, or structural crack.
Most concrete cracks will begin small, and grow over time. It is highly recommended to monitor the growth of any noticeable cracks and perform repairs as soon as possible.
If you want a more specific definition, then you’ll need to know (or at least have a good guess) the cause of the cracks.
Shrinkage Cracks, the true hairline cracks, occur before the concrete has fully cured. These types of cracks are harmless, and do not require repairs. The two types of shrinkage cracks are:
Drying Shrinkage Cracks (aka Crazing Cracks) : thin, surface level cracks that occur as a result of rapid water evaporation anytime during the curing process (up to 28 days after the pour).
Plastic Shrinkage Cracks: occurs during the concrete’s plastic state, before it has fully hardened, and has a range of weather-related sources.
Sources may include high winds, dry subgrade, dry climates, high temperatures, and more.
When someone labels a concrete crack as a “Structural Crack” they could be referring to Overload Cracks, Thermal Cracks, or Settlement Cracks. None of these types of cracks are inherently indicative of a lack of structural integrity, but may easily become structural over time if neglected (or with improper use).
Before diving into the different types of cracks which may inevitably become structural, it may be helpful to understand the definitions in the image below:
Fatigue or Overload Cracks are a type of concrete crack caused by exceeding the weight limits of a concrete structure. Overload Cracks may feature wide gaps or heavy vertical displacement, and should be taken seriously. While unlikely to occur with standard residential concrete slabs, overload cracks can happen, and may be more likely after heavy precipitation (due to the softening of the ground beneath the slab). As long as the concrete is only used for the purpose it was designed for, then you should have no problem avoiding this type of crack!
Settlement Cracks are often (not always) identified by vertical displacement in the structure, and require professional repair/replacement. These types of cracks are caused by improper compaction of the subgrade, or something causes the ground beneath the concrete to shift (i.e. poor compaction by utility installers, decomposing roots from tree removals, underground infestations, etc). It’s important to remember that settling is a natural characteristic of concrete, and will occur over time.
Thermal Cracks, also known as Freeze-Thaw Cracks and Heaving Cracks, are caused by a rapid and/or extreme change in temperature that influences a quick cycle of expansion and contraction. For example, a day of extremely cold weather followed by a day of significantly warm weather. Visually- these kinds of cracks may resemble Settlement Cracks and Overload Cracks. Although it cannot always be anticipated or prevented, any concrete contractor worth their trowel will monitor weather predictions, make necessary preparations for adverse weather, or -if necessary – reschedule the pour for a date with more favorable conditions.
Think you might have structural cracks? Considering a full or partial replacement? Click Here
3- Prevent, Inspect, and Repair Cracks
Beyond minor repairs and patchwork, most structural cracking or other damages will require a full or partial replacement of the concrete structure – common with concrete driveways, patios, and sidewalks.
Why? Because the best way to “repair” concrete is by preventing damage in the first place! A few ways to prevent damage to your concrete driveway, patio, or slab include…
Ensuring Proper Drainage
Aside from the constructing your concrete project, your concrete contractor should verify and optimize the design of your concrete to adhere to the flow of water throughout the property. Without proper drainage, your concrete could be at risk for significant damage.
Apply Sealant
Applying concrete sealant to your structure may increase resistance to water damage, stains, chemical damage, erosion, and normal wear-and-tear. Therefore, increasing it’s durability and aesthetic quality (highly recommended for preserving stamped concrete or other decorative concrete finishes).
Cleaning & Maintenance
Regular cleaning and maintenance of minor repairs can add years to the life of your concrete. It is recommended to have your concrete professionally cleaned at least once every two years, but ideally once per year. It’s also a good idea to monitor for cracks, proper drainage, and other possible issues throughout the year. Ignoring issues with concrete can have costly consequences, so it’s best to get ahead of them when you can.
Proper Use
All else constant, you have to make sure that the concrete structure is only used for it’s intended purpose, or at least within the limits of it’s design. Simply put – if you want your concrete to last, then it need to be able to withstand the conditions placed upon it. For example, a traditional residential driveway may crack under the weight of some larger trucks, farming equipment, or other heavy machinery. This is one of the many reasons why you should never cut corners in concrete design.
Virtue Concrete SC LLC is an experienced, licensed, and insured local concrete contractor that focuses on creating positive concrete experiences through craftsmanship, personalization, and punctuality.
So, if you’re concerned with cracking in your concrete driveway, patio, slab, or other concrete structure, then give us a call at (864)635-8048. We’d love to talk to you!
