What is the Crack Width in Concrete Structures to Prevent leakage?

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Title: What is the Crack Width in Concrete Structures to Prevent leakage?

Author(s): L. G. Mrazek

Publication: Special Publication

Volume: 204

Issue:

Appears on pages(s): 237-248

Keywords: crack width; deterioration; field measurements; leakage

Date: 8/1/2001

Abstract:
AC1 3 18-99 no longer refers to Z factors or crack width formulae as in previous editions of the code. Instead, AC1 318-99 correlates bar spacing with clear concrete cover, indicating that following these guidelines will reduce crack widths at the concrete surface. Field investigations have found leakage at certain type cracks which exhibit widths of .23mm (0.009”) or greater. Research and condition surveys completed by the author have found greater potential for concrete deterioration at cracks which extend to embedded reinforcement as compared with low slump, low water/cement ratio concrete having adequate cover over reinforcement. Current codes and standards present considerable variation with regard to recommended maximum crack widths to prevent leakage. Use of AC1 3 18-99 to design liquid or gas retaining structures could lead to designs that are not conservative, not durable and possibly unsafe, if preventing leakage is an important requirement for the particular facility.