Vector Corrosion Technologies Ltd Announces Acquisition of Post-Tech Construction Technologies .....read more->
 

The principal cause of corrosion of unbonded post-tensioned (PT) cables is the presence of moisture  and air inside voids along the cable sheaths. Moisture infiltration can occur from numerous sources including initial construction, ground water, roof leakage, and poor quality grout pockets.

PT cable corrosion occurs most often in unprotected structures such as parking garages, balconies and roof slabs; however numerous instances of cable wetness, cable corrosion and cable failure have been recorded at interior protected buildings.

Left unattended this corrosion can lead to cable failure, serious cable eruptions from concrete floors and costly cable repair and replacement.

Downloadable Files

Corrosion Evaluation and Mitigation for Unbonded Post-tensioned Concrete Structures

 

Early identification and mitigation of corrosive conditions can significantly reduce the costs of major repairs and the risk of structural failure. Where previously, non-destructive tests and methods of corrosion protection were not available, Vector’s Post-Tech evaluation, drying, and grease injection systems of testing and protection can now be used.

These systems can assist engineers and building owners in the assessment of overall cable conditions to formulate cost effective repair and preventative maintenance alternatives. When compared to conventional means of evaluation, structural reinforcement or cable replacement, significant cost savings can be achieved.

Post-Tech PT Corrosion Evaluation - Formerly CPE (Corrosion Potential Evaluation)

  • A non-destructive test used to identify heat sealed or push-thorough cables exposed to a "wet" or potentially corrosive environment

  • Determines the degree of wetness inside a cable sheath by injecting dry gas or air and measuring the moisture content in the exhaust from the venting ports.

  • Identifies the probable extent of current of future corrosion deterioration

  • Access areas used as "IN" ports can also allow for visual observation and testing.

      PT Schematic of Test Set Up

     PT Corrosion Evaluation Results Graph
Post-Tech PT Cable Drying - Formerly GP (Gas Purge)
  • An economical corrosion mitigation solution for unbonded post-tensioned cables encased in push-through or heat
    sealed sheaths.
  • PT Cable Drying purges moisture from the cable by cyclically pressurizing a dry, non-corrosive gas such as air or
    nitrogen into the cable sheath.
  • Process ensures that cable conditions are dry at the end of the treatment.
  • System can be adapted for temporary or permanent installation depending on severity and situation of cable
    corrosion.
  • Performance can be monitored manually or by means of electronic sensors installed for remote off-site
    monitoring and control.
Post-Tech PT Grease Injection
  • If a risk of future moisture infiltration exists, then the PT Grease Injection process is utilized to fill voids after cable drying.
  • After moisture is expelled with the PT Cable Drying process, rust-inhibiting, Post-Tensioning Institute (PTI) specified grease is injected under high pressure through installed ports or exposed cable anchors.
  • Grease has been proven to fill the cable voids and to penetrate cracks, defects and porous grout plugs through which moisture can otherwise penetrate.
  • Re-packing unbonded post-tensioned cables with corrosion-inhibiting grease provides a cost effective way to prevent or minimize further deterioration.
  • Extends the service life and integrity of structures at a fraction of the cost of other repair methods.

 

  

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