Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Cowboys cause post tension grout grief

Cowboy grouters are to blame for poor grouting in post tensioned slabs, it was claimed this week.

Post tensioning certifier UK CARES has highlighted the perils of ungrouted ducts in post tensioned slabs and estimated that approximately 1% of ducts are either partially or completely ungrouted.
"Poor workmanship is generally the cause," said a UK CARES spokesman.

"If people do the job properly, they should check the duct is clear of blockages and undamaged and they shouldn't be grouting in cold weather. Unskilled people may not know what to do when a blockage occurs"

The consequences of ungrouted or poorly grouted tendons may include strand corrosion, reduced shear and flexure capacity due to unbonded behaviour and unpredictable behaviour during demolition.

"The percentage of projects found with no grout is very low and it doesn't occur in most companies," said Ben Ume, a director for post tensioning design specialist Matthew Consultants.
"Also, most cases of ungrouted tendons are found before the building is handed over,” added Ume.

“My advice to clients with bonded tendons would be to use a Post Tensioning Association (PTA) registered company."

The PTA represents post tensioning companies and designers and promotes best practice.
Tests can be carried out on existing buildings by ultrasound, x-rays or by drilling holes, according to UK CARES and should be considered for existing post tensioned buildings where there is low confidence in the installation or if the building is in an aggressive environment.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.