New Service – “Pull Off” Strength Test for Fibre Reinforced Plastic

Our latest blog shares more information about the use of Fibre-reinforced plastic for structural strengthening and the importance of testing the […]

February 8th, 2018

Category: News

Our latest blog shares more information about the use of Fibre-reinforced plastic for structural strengthening and the importance of testing the pull off strength – a new service CSI is now pleased to offer.

Fibre-reinforced plastic (FRP) (also called fibre-reinforced polymer, or fiber-reinforced plastic) is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass (in fibreglass) glass (in fibreglass), carbon (in carbon-fiber-reinforced polymer), aramid, or basalt. Rarely, other fibres such as paper, wood, or asbestos have been used. The polymer is usually an epoxy, vinylester, or polyester thermosetting plastic, though phenol formaldehyde resins are still in use*.

Pull of strength test set up.

FRP has been widely used for structural strengthening. In particular, the applications of carbon fibre reinforced polymer (CFRP) to reinforced concrete structures continue to gain popularity in New Zealand. CFRP is mostly applied as externally bonded laminae to concrete surfaces using adhesive agent. The applications of CFRP have been shown to increase flexural and shear strengths of beam and slab structures, as well as providing extra confinement to columns which increase their compressive strength.

The effectiveness of CFRP strengthening depends on the quality of the FRP material itself, surface preparation, as well as the resin chosen for bonding. It is recommended to perform a quality control test after the application of the CFRP strengthening to structural concrete, through Pull-Off Strength testing.

As the demand has increased to perform the Pull-Off Strength Test, CSI has added this to the list of Services provided, and test to current ASTM D7522 standards.  Check out our new “Pull Off Strength Test” on the services page of the CSI website.

Wanting to find out more about innovative structural integrity testing?  Get in touch with CSI at or phone 0800 33 7767.

Winners of the 2016 Wellington Gold Awards in Emerging Services and finalists in the Deloitte’s Fast 50 ‘rising star’ competition 2017.


2 thoughts on “New Service – “Pull Off” Strength Test for Fibre Reinforced Plastic”

  1. Jack William
    June 21, 2018 02:41

    Oh Great! What an interesting topic. Thanks for sharing. FRP is one of the strongest raw materials used in these days. “Pull-off strength” test is the ultimate one to check the tensile strength of FRP.

    • Jane Concrete Structure Investigations
      June 22, 2018 13:11

      Yes strengthening with FRP has started picking up the pace in New Zealand. One notable example is the Grafton bridge in Auckland. It was important to perform this pull test for QA purposes, as FRP strengthening is only as effective as its bonding to the main structure. The lack of failure indicated excellent bonding; on the other hand – depending on the failure modes encountered, the weakest substrate can be found, which is also influenced by the quality of workmanship.

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