×
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

Oxygen and Concrete Curing

Oxygen and Concrete Curing

Oxygen and Concrete Curing

(OP)
Is oxygen used in the curing of concrete?  I'm looking for a cause of low oxygen levels in a new manhole.  Oxygen was measured at 2% and CO2 8% in a manhole that was 3 weeks old.

RE: Oxygen and Concrete Curing

Oxidation does occur during the curing process but not to extent of depletion of ambient oxygen supply.  Assuming this is an active manhole, I would look to the influent/effluent as being a probable cause.

Considering the levels you have noted, I would also check the instrument to see if it is reading properly.  Two percent oxygen is extremely low.  Have you checked for volatiles (methane, etc.)?

RE: Oxygen and Concrete Curing

(OP)
The manhole in question was a sealed watervalve manhole, ie no effluent.  The manhole was tested with three different monitors and the only gasses that were abnormal were O2 and CO2.  Thanks for your input.  Any other ideas?

RE: Oxygen and Concrete Curing

The only thing I can think of is that since the manhole is sealed, there could have been negative pressure created either by wind blowing across the top or by some other means of evacuation.  The concrete curing would not cause this condition.

RE: Oxygen and Concrete Curing

You may want to look at the soils that the manhole is in. If it is high in organics, the O2 is being used by the rotting of the organics. Check all the manholes within a few thousand yards. Mark this manhole well as a hazardous area. We had a guy go down when in a manhole with low O2. It also was a water valve MH. I know I had to pull him out.

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