What Causes Chipping Concrete in Your Poured Product?
Few things are as disappointing for a concrete crew as taking the time to plan and pour a project, only to have cracks mar the finished product. And chipping concrete doesn’t just lead to aesthetic issues. It has the potential to make a structure more vulnerable to moisture infiltration and environmental impacts, while also impacting its overall strength.
The best way to combat chipping concrete is to understand how it happens — and take meaningful steps to ward issues off before they begin. Here, our concrete experts lay out a few express chipping concerns that are common today, how they happen and tips for stopping them.
- Spalling Concrete: Spalling occurs when chunks of concrete break off and fall to the ground, and it ranks among the most dangerous concrete issues. Spalling typically occurs when reinforcement bars meet moisture and become rusted, leading to delamination inside the concrete or cracks that run from the bar to the outside of the concrete.
To avoid spalling concrete, ensure a proper concrete cover is in place over rebar. This protects against moisture intrusion. Using corrosion-resistant reinforcement where applicable can also help. In addition, quality waterproofing and drainage around the concrete structure can go a long way toward preventing spalling. - Cracked Concrete: Cracking is a natural byproduct of concrete wear and tear, and in many cases it does not pose a threat. Cracked concrete can occur due to shrinkage associated with having too much water in a concrete blend. Conversely, blends with too little water can also experience surface-level crazing cracks.
To avoid cracked concrete, we recommend paying careful attention to water-to-cement ratios during the mixing process. Later, use controlled curing methods to ensure even drying and reduce the chance of shrinkage or surface cracking. - Flaking or Scaling Concrete: Concrete flaking off at the surface level, also known as scaling, doesn’t typically pose a threat to safety unless it creates a trip hazard at the ground level. It can, however, serve as an early sign of deeper issues. Flaking or scaling concrete is a tell-tale sign that the material wasn’t mixed or installed properly. It often happens when water inside the mix wasn’t allowed the chance to properly evaporate before finishing, or when multiple freezes and thaws throughout a season put the material under stress for which it was not prepared.
To avoid concrete flaking or scaling, use air-entrained concrete mixes (blends that have air added in during the mixing process) if your pour takes place in areas prone to freezing temperatures. In addition, you should avoid sealing or finishing the surface too early. Proper curing practices and timing are key to allowing the mix to settle and bond as intended.