×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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.

Students Click Here

RCC Slab

RCC Slab

RCC Slab

(OP)
We are required to cast a RCC Slab of 600 mm depth and size 21M x 11M. in 2 parts of one day duration each ( Non-continuous) at 3.8 m lvl above G,.L. The constraints are: 1) Mixing of M20 grade of concrete ( Cement quantity 401 Kg.per Cu.M. of concrete) by concrete mixers at site and 2) Manual placing of concrete Questions are: What should be the sequence of concreting to avoid formation of a cold joint? Will there be any creep if at all such joints are formed? How the construction joints shall be treated to avoid such problems? Will use of chemicals for reducing setting time affect the strength of concrete? Any advise on the matter will be of great help Thanks

RE: RCC Slab

Your pour is only 139 cubic metres in volume.  Unless your site batcher is incredibly slow or you are placing concrete via a skip, then you should have few problems in completing this pour without a cold joint.

You can place the concrete either by direct tipping into a chute made from (say) a steel tube suspended from a crane for ease of handling, or you could use a concrete pump.

As for pouring procedure, start in one corner and keep two faces live with concrete as you move away from the corner.  If you are still concerned about cold joints then I suggest you use temporary stop ends from materials such as Expamet.  These are sheets of woven stainless or galvanised steel through which your rebar can be punched.  Once the concrete reache the expamet it tries to pass through but can't.  This leaves a very rough key for the next stage of your pour to bond onto with no scabbling or pre-treatment required.  Traditional timber temporary stop ends could be used but need a good concrete gang working with them.

Regarding admixtures, you need a retarder to extend the fluid life of the concrete in order to prevent cold joints.  This will inhibit the rate of strength gain initially but should not affect the design strength of the concrete.

Regards

Andy Machon
Andy@machona.freeserve.co.uk

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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