Tensile adhesion strength after freeze-thaw cycles in MPa evaluated as the maximum adhesion strength effort that it has by applying, after 25 freeze-thaw cycles between (-15 ± 3)°C and (15 ± 3)°C, a force at constant intervals of (250 ± 50) N/s at the tile layer type V1 (50 ± 1) mm x (50 ± 1) mm placed on the surface of the adhesive applied on a concrete substrate as specified in EN 1323. The preparation and instrumentation are identical to those described in the test for the determination of the adhesive strength, times and curing mode change. The end result is the adhesive strength (maximum measurable resistance for unit surface area by pull-off or cutting test) (UNI EN 120004). The test method is described in EN 1348 and provides for determination of resistance by pull-off on cementitious adhesive resistance for ceramic tiles. It can be adapted to cementitious premixed adhesives or separate components for interior and exterior floors and walls (UNI EN 1348). 
For the tests, you need of 10 square ceramic tiles of dimensions (50 ± 1) mm x (50 ± 1) mm, 10 metal plates of dimensions (50 ± 1) mm x (50 ± 1) mm and minimum thickness of 10 mm with connection to Pull-Off, a Pull-Off able to apply a force of (250 ± 50) N/s, the loads able to exert a force of (20 ± 0.05) N with a section of 50 mm x 50 mm, a notched trowel and a concrete slab (the characteristics are defined in the UNI EN 1323).

To carry out this test, prepare a minimum 2 kg of adhesive (primarily housing for the liquid in the mixer, then the mass and mixed for 30 seconds. After removing the paddle, it is necessary clean it and mix it again finally for 1 min).

Once the adhesive is prepared, apply a thin layer on the concrete slab, with a smooth trowel, then a thicker layer with the notched part of the trowel (with an angle of 60 ° compared to the support). We must make cure the sample (under standard conditions) for 7 days and subsequently it must be immersed in water for 21 days before to preform 25 freeze-thaw cycles. Each cycle includes:

  • removal sample from water and positioning it in the cabinet, in order to achieve (-15 ± 3 °)C for 2 h ± 20 min;
  • sample immersion in water at (25 ± 3 °)C and increasing of temperature at (15 ± 3 °)C;
  • maintain the sample at temperature of (15 ± 3 °)C for at least 2h, before restarting a new cycle.

In the final cycle the sample must be removed from water,it must be dried with a cloth and the metal plates must be applied. After 24 h, under standard conditions, it is necessary to measure the adhesion strength.

After using the Pull-Off you can have different types of breaking, ie:

  • adhesive breaking between adhesive and substrate;
  • adhesive breaking between tile and adhesive;
  • adhesive breaking between tile and adhesion plate;
  • cohesive breaking in the adhesive;
  • cohesive breaking in the support;
  • cohesive breaking in the tile.

 

Material type Standard Test method
adhesives EN 12004 EN 1348
waterproofing EN 14891 EN 14891 §A.6.6

 

Instruments used to perform the test: Pull-off

 

Initial adhesion strength after freeze-thaw cycles valuated as the maximum adhesion strength effort that it has by applying, after 25 cycles of freeze/thaw, a force at constant intervals at the tiles layer on the adhesive surface applied on a concrete support.