×
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

Continous Concrete Placement

Continous Concrete Placement

Continous Concrete Placement

(OP)
What is the maximun time that we can have between concrete trucks if we want have a continous concrete placement? I was pouring concrete a week ago and I had a gap between two of the truck of about 45 min. Is there anywhere a definition of continous concrete placement?

RE: Continous Concrete Placement

It depends on several variables....the weather conditions at the time, the mix design, the construction techniques...

If the weather was warm and dry, you might have a cold joint in the concrete.  45 minutes isn't all that long, but depending on the water-cement ratio and the weather conditions, it could happen.

For efficiency of placement, you always want to have trucks staging and ready to discharge, but the queue should not be so long as to have the concrete sitting in the trucks for more than about an hour from time of batching to time of placement.  ASTM C94 sets a 90 minute time limit, but as a practical matter, that can be too long.

RE: Continous Concrete Placement

(OP)
Concrete pour started at around 8:00 am, Temp that morning was around the 70's and water-cement ratio was 0.45. We were pouring a concrete pier for job under the Army Corps of Engineers job and the were trying to say that we had a cold joint, however, when we stripped the forms we could not see any cold joints.

RE: Continous Concrete Placement

Get the mill certificate on the cement that was used in the mix.  Check the time of initial set.  If your time delay was under that time, you should be ok.

When the new concrete came, was the old concrete still in a plastic state?  Could it be vibrated?  If yes to both of those, then you likely do not have a cold joint.

The form face can be misleading for cold joints, though with a 0.45 w-c ratio, you probably don't have much excess bleed water or runny paste.

If they have rejected the concrete pier, then do ultrasonic testing to check the continuity and integrity of the concrete before you accept their rejection.

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