Why does my concrete crack and how can I prevent it?

Southaven's climate and soil conditions pose unique challenges:



- Expansive Clay Soils

• Central and northern Mississippi often rest on expansive clays that swell when wet and shrink when dry, exerting up to 25,000 psf pressure on foundations and slabs
• As the soil shifts, concrete above it can move unevenly, resulting in cracks or even structural damage.

- Temperature Swings and Humidity

• Hot, humid summers followed by cooler months can cause the concrete to expand and contract.
• Rapid drying of fresh concrete in summer may lead to surface "crazing" or shrinkage cracks.

- Improper Mixing, Finishing, or Curing

• Adding too much water weakens the mix and increases shrinkage upon drying.
• Failing to cure properly—keeping the concrete moist after pouring—can reduce its strength by up to 50 %.

- Inadequate Base Preparation or Reinforcement

• Poorly compacted soil or organic debris below the slab invites settling.
• Lack of proper reinforcement (rebar, wire mesh, fibers) makes concrete more susceptible to cracking under load or movement .

- How to Prevent Cracks

• Soil Preparation

• Excavate organic topsoil and replace with properly compacted gravel or crusher-run base.
• Consider soil stabilization methods for expansive clay, such as drainage solutions or geotextile reinforcements.

• Use Reinforcement

• Include rebar or wire mesh in driveways, foundations, and patios.
• For lighter applications, fiber-reinforced concrete adds strength to reduce shrinkage cracks.

• Control Joints & Proper Curing

• Install control joints to direct where cracks will occur.
• Keep concrete moist for 5–7 days in moderate climates, and longer in hot or cold weather concretenetwork.com.
• Use curing compounds or light coverings after finishing to retain moisture.

• Correct Concrete Mix & Additives

• Avoid excessive water—maintain the recommended water-cement ratio.
• Consider adding admixtures like plasticizers, fibers, or retarders to control set time, reduce shrinkage, or strengthen the mix.

- What to Do About Existing Cracks

• Hairline/Shrinkage Cracks
• Usually only cosmetic. Can be sealed with crack fillers for aesthetics and protection.
• Settlement or Structural Cracks
• Indicate subgrade issues. May require lifting/leveling methods like mudjacking or slabjacking, or complete repair under structural engineer guidance.
• Spalling or Surface Degradation
• Often results from freeze‑thaw cycles or poor finishing.
• Resurfacing or sealing can restore usabilty and appearance .

Our Conclusion

Cracking is not unusual in Mississippi, given the soil, weather, and finishing factors. But by:

• Preparing the base correctly,
• Using proper reinforcement,
• Installing control joints,
• Curing properly,
• And sealing/maintaining the finished concrete, uou’ll significantly reduce cracking and extend the life of your concrete investment.