Post-Tech^® PTI Impregnation

The repair and protection of grouted/bonded post-tension tendons can present unique challenges when a corrosion risk is present due to the presence of voids and defective or contaminated grout. The Post-Tech® PTI system has been specifically engineered to mitigate or avert corrosion in bonded post-tension tendons by taking advantage of the naturally occurring interstitial spaces in stranded high strength steel tendons. The Post-Tech PTI corrosion protection material is applied under pressure and travels along the length of the strand while also penetrating into the grout surrounding the wires.

The foundation of the Post-Tech® system is a formulated low viscosity dual action hydrocarbon silicon polymer resin. The anti-corrosion Post-Tech® PTI impregnation material has a greater affinity to steel surfaces than water and displaces moisture from the steel surface to form a protective barrier on any exposed steel surfaces. The impregnation material permeates between the wires of the strand to impregnate the grout surrounding each strand to provide an additional barrier to moisture and oxygen.

The Post-Tech® PTI impregnation process can be completed from the end anchorage or from intermediate locations along the length of the tendon. Experience has shown the Post-Tech® PTI material can flow through the interstitial spaces at least 250 ft (75m) along the length of a tendon from a single-entry point.

Features and Benefits

• Low viscosity: travels under pressure in interstitial spaces along the length of the tendon.
• Film forming: provides a protective barrier to exposed steel surfaces.
• Moisture protection: penetrates into grout creating a zone of impregnation around the steel.

Untreated control sample strand (left) vs. strand treated with Post-Tech® PTI impregnation material (right).

Test illustrating the protective film forming properties of the Post-Tech® PTI material. The top left quadrant of the steel plate was not dipped in the PTI material, the top right was dipped once in the PTI material and bottom was dipped twice.  The whole plate was then was exposed to anan accelerated salt water bath for multiple days.