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


striking of vertical formwork

striking of vertical formwork

striking of vertical formwork

Hi, looking into striking times of vertical formwork normally in water retaining applications. We typically use ggbs replacement mix. Apart from strength considerations what is minimum striking time used by others here? the ggbs will slow the strength gain and prolong the heat gain (although lower temps than non replacement mix). we have various 'guidance' here in UK and have advised site on times.

RE: striking of vertical formwork

When final finish is critical for architectural work (I don't do much work with water tanks), we will try to use a performance based stripping criteria (I am an engineer for a formwork and shoring company). From the commentary to ACI371-98 Guide for the Analysis, Design, and Construction of Concrete-Pedestal Water Towers, a minimum compressive strength of 800psi (5.5 MPa) is suggested for most situations.

A prior search of ACI documents provided a minimum strength of 1000 psi for stripping/striking of vertical formed surfaces for architectural finishes.

In a recent support structure for a government project, we did not strip until 1500 psi was attained and had little if any damage due to form removal.

The added cost of using a perrformance based spec is additional cylinders and additional testing, but the ability to actually know when things should be done is certainly worth it in our eyes.

Hope this helps,

Daniel Toon

RE: striking of vertical formwork

similar spec here in UK though dictates strength must be 10 N/mm2 or twice subjected stress whichever greater. By conversion 10 is slightly higher than your psi figure of 1000. Slightly different with water retaining in that crack limits are obviously more onerous and shrinkage/thermal cracking consideration usually dictate. Many reports and guides but was looking for any 'real' examples other than our sites.

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!


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