Concrete Cracks Within the First 3 Months | Concrete Design of KC

Concrete Cracks Within the First 3 Months

Cracks that appear within the first three months after a concrete pour are known as early-age cracks. These are fairly common in the industry and typically fall into the following categories:

1. Plastic Shrinkage Cracks

  • Timing: First few hours to days
  • Appearance: Random, shallow, spiderweb-like
  • Cause: Rapid surface moisture loss (wind, heat, low humidity)
  • Impact: Mostly cosmetic; not structural

2. Drying Shrinkage Cracks

  • Timing: Days to weeks
  • Appearance: Straight or curved, often near joints or corners
  • Cause: Water evaporating as concrete cures
  • Impact: Common and expected; generally not structural if joints are properly placed

3. Settlement Cracks

  • Timing: Hours to first few days
  • Appearance: Linear, often over rebar or near walls/columns
  • Cause: Concrete settling unevenly or around reinforcement
  • Impact: May require attention if near rebar due to risk of corrosion

4. Thermal Cracks

  • Timing: First days to weeks
  • Appearance: Wider cracks at restraint points
  • Cause: Temperature differences during curing
  • Impact: Can be significant in large pours; preventable with proper mix and curing

5. Crazing

  • Timing: First few days to weeks
  • Appearance: Fine surface cracks in random patterns
  • Cause: Rapid surface drying or over-troweling
  • Impact: Aesthetic only; not structural

Should You Be Concerned?

  • Hairline cracks are typically normal and not structural.
  • Wider cracks (>1/8") or those that worsen over time may need evaluation.

Tips to Prevent Early Cracking

  • Ensure proper curing practices (especially in hot, dry weather)
  • Use correctly placed and timed control joints
  • Avoid over-finishing
  • Manage water content in the mix
  • Ensure stable, compacted subgrade

If you have questions or are noticing early cracks in your concrete, contact our team at Concrete Design of KC for professional insight and solutions.