The purpose of this test is to determine the adhesion strength between a screed and a normalized support. Equipment used to perform this test consists of two instruments:

  • core drill and diamond-drill bit crown that allow the drilling of a cylinder (50 ± 1.0) mm in the product. The crown has a sharp edge that protrudes from the body (1.5 ± 0.5) mm, (to reduce the lateral forces that are applied on the test surface);
  • device to measure the adhesion strength with an integrated motor that allows for a constant load automatic measurement. The adhesive stress is applied by rotating the crank positioned over the device. The digital display allows you to view the applied load directly. The instrument is equipped with an internal memory capable of storing the entire pull-off measurement. It allows to apply an adhesion strength in a range of 1.6 kN-16 kN.

The sample is of minimum dimensions 300 mm x 300 mm x 50 mm and the product is lying on a concrete substrate realized with aggregate with maximum size of 10 mm, water/cement ratio 0.40 and the cement content of 455 kg / m3. The system is cured for 28 days in normal conditions and this will be performed five tests of adhesion. After 28 days to make the coring. Drill with a diamond-drill bit crown with 90 ° axis to the surface. Five areas of cross section of about 50 mm are subjected to core. The test areas must be at least 50 mm away from each other and at least 50 mm away from the edge of the sample. The cut must penetrate for the entire screed and for more than 5 mm deep in the substrate. Then apply the steel plates with an adhesive on the five carotate areas. Finally, place the device to measure the adhesion strength. Apply force through the device and the display will show the breaking load (kN) at the time of breaking. It must be calculated the strength of individual sample dividing the breaking load (kN) for the test area (mm2). The adhesion strength is calculated as the mean of 5 individual values. By means of a visual evaluation it can be determined the type of sample breaking. The types of breaking are as follows:

X = cohesion breaking in the concrete substrate;

X / Y = breaking between the substrate and the screed;

Y = cohesion breaking in the screed;

Z = breaking between the adhesion layer and the plate with the pulling head.

 

Material type Standard Test method
screeds EN 13813 EN 13892-8
self-levelings EN 13813 EN 13892-8

 

The test consists to determine the adhesion strength between a screed and a normalized support, by pull-off.The test consists to determine the adhesion strength between a screed and a normalized support, by pull-off.The test consists to determine the adhesion strength between a screed and a normalized support, by pull-off.

The test consists to determine the adhesion strength between a screed and a normalized support, by pull-off.