Why Does Concrete Crack?: The Top 7 Causes

Concrete is renowned for its durability and versatility. However, despite its reputation for strength, concrete is not impervious to wear, tear, and damage. The deterioration of concrete can manifest in various ways, but one of the most common and concerning issues is cracking.

In this article, we explore the primary causes of concrete cracking, examining how each factor contributes to the deterioration of this seemingly indestructible material. We also touch on how to protect and repair your concrete structures.

The condition and type of soil beneath concrete slabs play a crucial role in their stability and longevity. Different soil types exhibit varying drainage properties, which can affect concrete differently. Soil that drains too well can easily erode, while expansive clay soils may retain excessive water, leading to constant swelling and shrinking.

Both scenarios result in inadequate support for concrete slabs, creating voids underneath. These voids can lead to uneven settling and cracking. For example, settlement cracks often occur when concrete is poured over unsuitable ground, such as areas with decomposing tree roots or improperly compacted utility trenches.

Excessive rainfall can be detrimental to concrete structures. Beyond causing surface issues like flaking and staining, rain can erode the soil that supports concrete slabs. As water washes away the underlying soil, voids form beneath the concrete. Without proper support, the concrete may begin to collapse or crack over time, eventually crumbling inward. This process not only compromises the structural integrity of the concrete but also creates an unsightly appearance.

Periods of drought can exacerbate cracking in concrete surfaces, including sidewalks, driveways, and even foundations. The lack of water prompts the soil to dry up and shrink, leaving concrete without proper support. For example, expansion cracks occur when concrete expands in hot weather and creates stress if there is no room to expand.

Trees develop extensive and robust root networks that are crucial to soil health. However, these same powerful roots can pose significant problems for nearby structures. Tree roots, in search of moisture and nutrients, displace the soil. As these roots grow and spread underneath concrete slabs, they can cause the concrete to crack, heave, or lift. Driveways and sidewalks are especially vulnerable to this type of damage.

The quality of concrete installation significantly impacts its long-term durability. Poor installation practices can lead to permanent issues. For instance, concrete poured during cold months without proper heating is more prone to cracking. This is often due to inadequately compacted ground bases.

Additionally, using too much water in the concrete mixture or incorporating substandard materials can weaken the concrete, making it more susceptible to environmental damage. Excess water in the mix can reduce concrete strength, leading to shrinkage and cracking as it dries and hardens. Rapid drying of concrete can also increase cracking likelihood by disrupting the hydration process, which requires water and continues for weeks after pouring.

While concrete is known for its strength, it has limitations. Consistent placement of excessive weight on concrete slabs can cause them to crack and sink over time. This issue is particularly common in driveways and garages, where heavy vehicles might be parked for extended periods.

Consider that the average vehicle weighs over 4,100 pounds, according to the Environmental Protection Agency. This substantial weight, when concentrated on a concrete surface for long periods, can exert significant stress on the material, potentially leading to cracks and structural problems.

Repeated and sudden freeze-thaw cycles can be particularly damaging to exposed concrete surfaces like driveways and sidewalks. Concrete’s porous nature and lack of tensile strength make it vulnerable to moisture-related damage.

When exposed to persistent dampness, concrete absorbs water. During freeze-thaw cycles, this absorbed water expands and contracts repeatedly, causing stress within the concrete structure. Initially, this may lead to cosmetic issues such as pitting, flaking, scaling, and surface cracking. However, if left unaddressed, these seemingly minor problems can quickly escalate into heaving cracks and more serious structural issues, compromising the integrity and safety of the concrete surface.

• Seal the concrete to prevent damage
• Ensure the concrete has proper expansion joints
• Maintain adequate drainage around concrete
• Manage tree roots

• Regularly clean concrete surfaces
• Evenly distribute weight on concrete
• Opt for professional crack repair
• Invest in professional concrete lifting

Concrete can crack and sustain damage for many reasons, and it’s important to properly diagnose these causes to implement the best solution. Our team at Groundworks has many years of experience with inspecting and repairing concrete surfaces with our innovative polyurethane injections.

Contact us to schedule a free inspection and repair estimate. After a thorough evaluation, we’ll create a customized plan to meet your repair needs and budget. Get started improving your home’s safety and appearance today!