×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Chert in concrete aggregate

Chert in concrete aggregate

Chert in concrete aggregate

(OP)
We have 6 concrete cooling towers (wet/dry cycles are common) that are fast deteriorating by spalling. We suspect that chert was used in the aggregate and that it is causing chunks to pop at the surface. I need information on the behavior and composition of chert. The chert near the surfaces are poping now, but how about the chert that is deep in the wall? (12 thick and thicker) is that chert also deteriorating inside?. How is best to repair? Can a waterprofing coat with a high-tech material help? or retard deterioration of the cooling towers. The are about 5-years old.  Your insights will be appreciatted

RE: Chert in concrete aggregate

You will first need to characterize the chert.  The common reactive form of chert is chalcedony.  This is usually a relatively soft, greenish tinted material present in limestone/dolomitic strata.

Most often, this chert is reactive only near the surface where it exerts enough stress to cause surface popouts, but not enough to cause serious internal problems in thicker sections of concrete.  Surface coatings may serve to exacerbate the problem, not correct it.

The reactants can be characterized by a petrographic evaluation of the concrete and its deterioration potential can be assessed from this exercise.

RE: Chert in concrete aggregate

(OP)
Thank you Ron. A petrographic analysis will be underway. The chert we have is actually light brown (tan). Is this a different type of chert?. Your answer seem to imply that there are other cherts that have different mechanical or chemical behavior. Your opinion is appreciated.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources