Concrete is one of the most durable and versatile materials in construction, but it’s not immune to problems. Even when poured correctly, concrete can develop cracks that affect both its appearance and integrity. Understanding why these cracks occur and how to prevent them is essential for maintaining long-lasting, professional-quality results.
1. Shrinkage Cracks
Shrinkage cracks are among the most common types of cracks that appear as concrete dries and hardens. As the water in the mix evaporates, the concrete slightly contracts. If the surface dries faster than the interior, small cracks can form.
How to prevent it:
- Use a well-designed concrete mix with the right water-to-cement ratio.
- Place control joints at regular intervals to manage shrinkage movement.
- Keep the surface moist during curing, especially in Alberta’s dry summer climate.
Prevention tip: Proper curing is key. Keep the surface moist for several days after pouring, and avoid pouring concrete during extreme heat or wind that speeds up evaporation.
2. Settlement Cracks
Settlement cracks occur when the ground beneath the concrete moves or compresses unevenly, causing parts of the slab to sink or settle. This often happens when the subgrade isn’t compacted properly before the pour.
How to prevent it:
- Compact the soil thoroughly during site preparation.
- Add a solid gravel or crushed-stone base to provide stability and drainage.
- Hire experienced excavation professionals to ensure the subgrade is even and secure.
Prevention tip: Always ensure the soil base is firm, level, and well-compacted before placing concrete. Adding gravel or a crushed rock base can also improve stability and drainage.
3. Structural Cracks
Structural cracks are usually wider and more severe, often caused by heavy loads or poor reinforcement placement. They can indicate deeper issues that require professional attention.
How to prevent it:
- Include expansion joints between slabs or against fixed structures.
- Use reinforcing steel or wire mesh to help distribute thermal stress.
- Choose a concrete mix designed for local temperature variations.
Prevention tip: Work with an experienced concrete contractor who understands load-bearing requirements and proper rebar placement. Reinforcing the concrete correctly can prevent these cracks from forming under stress.
4. Temperature Cracks
Concrete expands and contracts with temperature changes. Without proper expansion joints, this movement can create stress that leads to cracking.
How to prevent it:
- Make sure your slab thickness matches the expected use (e.g., driveways vs. walkways).
- Reinforce concrete flatwork for areas that will hold vehicles or heavy loads.
- Work with an experienced concrete contractor
Prevention tip: Install control and expansion joints in large slabs to give the concrete room to move as temperatures fluctuate. The placement and spacing of these joints are critical for preventing cracks over time.
5. Cracks from Overloading
Even well-poured concrete has its limits. Heavy vehicles, machinery, or equipment that exceed the slab’s load capacity can cause cracks or structural damage.
How to prevent it:
- Ensure even placement and vibration of the concrete mix.
- Avoid overworking the surface during finishing.
- Keep reinforcement properly supported and secure.
Prevention tip: Know the weight limits of your concrete surface, especially in driveways or industrial areas. If heavy use is expected, your concrete contractor can adjust the mix and thickness accordingly.
6. Plastic Shrinkage Cracks
These fine, shallow cracks appear soon after the concrete is poured, often caused by rapid moisture loss at the surface while the concrete is still plastic.
How to prevent it:
- Avoid finishing the surface too early or when bleed water is still visible.
- Apply curing compounds or water sprays to slow the evaporation process.
- Protect the concrete from wind and direct sunlight during the early curing phase.
Prevention tip: Use windbreaks, sunshades, or surface retarders during placement to slow evaporation. Maintaining consistent moisture helps ensure an even cure.
7. Corrosion-Related Cracks
If reinforcing steel inside the concrete begins to corrode, it expands and creates internal pressure that causes cracks.
How to prevent it:
- Use corrosion-resistant rebar or coatings in exposed environments.
- Seal the surface of concrete flatwork
8. Cracks from Poor Workmanship
Improper mixing, inadequate finishing, or failing to follow curing procedures can all contribute to cracking. Even something as simple as overworking the surface can weaken it.
How to prevent it:
- Choose a trusted local concrete company with proven experience.
- Ask about site preparation, mix design, and reinforcement methods.
- Work with contractors like FramCon who follow best practices for both residential and commercial projects.
Building Concrete That Lasts
Cracks in concrete aren’t always avoidable—but most can be prevented with the right preparation, materials, and expertise. From site grading and proper reinforcement to professional finishing and curing, each step plays a role in creating strong, long-lasting results.
If you’re planning new concrete flatwork or need expert help addressing cracks, a qualified concrete contractor can assess your needs and recommend the best solutions for your project.