Pull off adhesion test : choice and influence of the diameter of the dolly

[kinkin28]

Hello,

I am a french material engineer.

I want to carry out pull out tests on coatings applied on steel surface and concrete surface.

So my questions are :

- Do you know why the diameter of the dolly is different between concrete surface (50 mm) and steel surface (20 mm or < 20 mm)?

- Is there an influence of the diameter of the dolly on pull out test results ?

Thanks for your answers

 

[berkshire]

Je suis désole double signalisation n’est pas autorisée
B.E.

You are judged not by what you know, but by what you can do.

 

[TomDOT]

The concrete substrate is more heterogeneous. Lots of concrete has aggregate larger than 20mm. Using a larger dolly means a more "representative" answer.

 

[TomDOT]

One more reason: Instrument limits.

The ultimate potential strength of a pulloff on concrete is much lower than on steel. I have seen steel pulloffs at 5000 PSI. Rarely would you see concrete pulloffs of 500 PSI.