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!

*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.

Jobs

Adding super plasticizer at site

Adding super plasticizer at site

(OP)
Good day everybody,

I have some concern regarding adding super plasticizer at site just before discharge of ready mix concrete. Our footing designed with lot of rebars so we need a flowable concrete for workability. Our mix design includes plasticizer and retarder admixtures but when arrived at site, the concrete slump is a bit lower, so it needs additional SP. Is there adverse effect if applying overdosage of plasticizer? Please any expert on concrete works if I may have your comment on this..Thank you..

RE: Adding super plasticizer at site

First of all, Super-P is somewhat of a crutch. It's not going to help much in congested reinforcing. Aggregate size and good vibration help much more. But contractors think it helps, so I let them have it.
Why do you think they will overdose the Super P? It's not free, so the concrete guys don't throw it around willy nilly. I suspect that you'd really have to overdo it to have an effect on the concrete.

RE: Adding super plasticizer at site

2
foxview11....this indicates to me that your ready mix supplier is not controlling the mix as they should. If you are losing slump quickly after a SuperP addition at the plant, you will typically see that either the transit time is too high or the aggregates have a moisture content that is too low and they are "sucking" in the water and reducing the slump.

While plasticizers used to be added at the site because of their low effect time, better formulations have allowed plant addition for over 20 years. I do not recommend the addition of plasticizer at the site because of control issues and the inability to properly disperse the plasticizer in the mix.

RE: Adding super plasticizer at site

(OP)
Thanks Ron..if necessary to add super P, does it not affect concrete strength? and also, what is the usual dosage to add super P at a certain slump, say 100mm?

RE: Adding super plasticizer at site

foxview11.....dose rates are given by the SuperP manufacturer.....it varies by manufacturer and cement content. SuperP does not affect the concrete strength directly, but indirectly it increases the strength because usually less water is required, thus decreasing the water-cement ratio.

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close