Adhesive tensile strength

The adhesive tensile strength (inaccurately also tear-off strength ), formula symbol , serves as a characteristic value for the adhesion or adhesion of layers such as plasters , screeds , coatings or paints on concrete surfaces. It is determined with the help of the pull-off test (rarely also a tear-off test). ${\ displaystyle \ beta _ {HZ}}$

The adhesive tensile test does not differ from the surface tensile strength test on concrete surfaces with regard to the test device and the test sequence . In contrast to the adhesive tensile test, the surface tensile strength test determines the cohesion at the concrete edge zone.

Test procedure

According to DIN EN ISO 4624, the adhesive tensile strength is determined under defined conditions (measuring surface, temperature, take-off speed, etc.). A stamp (test stamp) glued to the coating of the test body is pulled off evenly and slowly by means of a tensile testing machine perpendicular to the surface of the test body until it breaks . When it is torn off, the coating, including the stuck-on stamp, separates from the surface of the test body. Therefore, the bond must adhere more strongly to the coating than the coating to the test specimen.

The measured value of the adhesive tensile tear strength can never be higher than the intrinsic strength of the individual components, test specimen and coating, whereby the weakest link is always decisive in a composite: ${\ displaystyle \ beta _ {Z}}$

{\ displaystyle \ beta _ {HZ} \ leq {\ text {min}} (\ beta _ {Z1}, \ beta _ {Z2})}

In addition to the measured value, the description of the location of the break is decisive: where did the break occur?

Norms and standards

DIN EN ISO 4624 Coating materials - Tear-off test to assess the adhesive strength
DIN EN 1542 Products and systems for the protection and repair of concrete structures - Test methods - Measurement of adhesive strength in a tear-off test
DIN EN 13596 - Waterproofing membranes - Waterproofing systems on concrete for bridges and other traffic areas - Determination of tear strength
DIN EN 1015-12 - Test method for mortar for masonry - Determination of the adhesive tensile strength of hardened plaster mortar

Individual evidence

^ Andreas W. Momber, Rolf-Rainer Schulz: Handbook of surface treatment concrete , Birkhäuser Verlag, 2006, ISBN 3-7643-6218-9 , page 400.

Web links

Surface Tensile Strength - Adhesive Tensile Strength (accessed October 10, 2019)
Testing the surface tensile strength of concrete (accessed October 10, 2019)
STATIC AND DYNAMIC ADHESIVE STRENGTH OF REINFORCED CONCRETE LAYERS (accessed October 10, 2019)
Development of a test method to determine the adhesive strength of road marking films (accessed on October 10, 2019)

[1] Andreas W. Momber, Rolf-Rainer Schulz: Handbook of surface treatment concrete , Birkhäuser Verlag, 2006, ISBN 3-7643-6218-9 , page 400.