Hayder Seeks: Causes of Exterior Concrete Defects

07.17.18   Hayder H. Al-Hilal, PE, SMSI, CIP-1, CCI-2, Level 1 Thermographer, ICRI CSMT | More by this Author

Hayder Seeks: Causes of Exterior Concrete Defects

FAQ: Hayder, my concrete is chipping away! What is going on?

Peeled, scaled concrete surfaces.

Delaminated and scaled concrete surfaces.

Answer: Your “chipping” concrete could be related to any one of several causes of exterior concrete scaling and peeling defects, including:

  • Insufficient curing after concrete placement. The lack of appropriate curing measures will result in rapid loss of moisture from the concrete surface layer, leading to a weak skin that can be prone to scaling and peeling, resulting from freezing and thawing effects, or from exposure to moisture and dicing salts.
  • Use of non-air-entrained concrete.
  • Poor finishing practices, such as finishing while bleed water is on the surface or when adding excess moisture into the top of concrete during finishing to make finishing operations easier. This results in a low-strength concrete surface layer because bleed or excess water is worked back into the concrete surface. Excessive finishing can also result in reducing entrained air in the concrete surface layer, leading to surface scaling and peeling.  

A definitive conclusion regarding the root cause(s) of these concrete surface defects is not possible from a limited visual and sounding assessment alone. A petrographic analysis on a concrete core sample extracted from the concrete placement is recommended if a conclusive finding is required. This analysis can usually determine the cause(s) of such surface defects through a thin section analysis of the extracted concrete core. Petrographers study properties of the near-surface core region concrete and compare them to properties of deeper core regions.

If your concrete pavements or sidewalks exhibit surface scaling and peeling, SME can help you determine the root cause for these defects. Contact Hayder Al-Hilal for more information.

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