We are still carrying out essential works on assets with additional safety measures.

Post Tensioned Investigations

Preventing total Bridge collapse

A Post-Tensioned Inspection is the only way to identify any voids, or corrosion within the post tensioned duct system. HTA are one of only a few who have the experience required to identify the difference between reinforcing bars, and the sheath material.

Post Tensioned Investigations by HTA

UKAS Accredited for Post-tensioned Investigations

Here is a list of post-tensioned projects HTA have carried out:

  • Cambridge / Herts – Multiple Bridges (Owen Williams)
  • Exeter - A31(Highways Agency)]
  • M27 – Multiple bridges (Highways Agency)
  • M3 – Multiple bridges (Highways Agency)
  • 2 No bridges in Eire (NRA – National Road Authority) – Largest PTSI in Eire to date
  • Hammersmith Flyover (TFL)
  • Crosshall Bridge – A1 (Highways Agency)
  • Harrow Manorway – (LB of Bexley)
  • Coolock Interchange – (NRA)
  • 2 Rail bridges in Herts (Herts Highways)

Post Tensioned Air Voids

In some occasions air voids can be created within the sheath during the grouting procedure.  A common cause is from Bleed water being reabsorbed into the grout, leaving air voids where the water had accumulated. Bleed water rises to the highest point, and is created from improper mixing of the grout.

Other reasons for voiding can be:

  • The duct may be improperly vented, allowing air pockets to be formed.
  • The pumping system can introduce air into the system
  • The grout can be pumped too fast through the duct and cause turbulent flow entrapping air bubbles.