Surface tensile strength testing of concrete
The surface tensile strength test of concrete is a standardized test method with the help of which the surface tensile strength (imprecisely also tear strength ) of concrete layers close to the surface can be assessed. The surface tensile strength describes the maximum tensile force , based on a defined test area of a test stamp and acting at right angles to the plane of the prepared concrete substrate , that is required to generate a cohesive break in the concrete edge zone. The test, sometimes also called pull-off test or tear-off test, serves, for example, to determine in which way the concrete surface must be pretreated for a successful concrete repair.
The surface tensile strength test is not to be confused with the adhesive tensile test, which is used to test the tensile strength ( adhesion ) of layers ( e.g. plaster or paint ) on concrete surfaces. The test device and the test procedure for the adhesive tensile test are identical to those for the surface tensile strength test.
Examination procedure
First of all, a test area is created which is delimited by an annular groove and which must be sufficiently dry for bonding . All planned substrate preparations (high-pressure water blasting , shot peening , solid matter blasting , grinding , etc.) must be carried out on this concrete surface to be tested so that a target-oriented result is achieved.
To test the surface tensile strength, three cylindrical steel disks (test stamps) with a diameter of 50 mm and a thickness of 30 mm, usually with a methyl methacrylate adhesive (MMA adhesive), are then glued to the surface to be tested and a servohydraulic adhesive tensile tester (pulling devices according to EN ISO 6892) deducted.
Norms and standards
- Guideline for the protection and repair of concrete components (Rili-SIB)
- DIN 1048-2 test method for concrete; Hardened concrete in structures and components
Individual evidence
- ^ Andreas W. Momber, Rolf-Rainer Schulz: Handbook of surface treatment concrete , Birkhäuser Verlag, 2006, ISBN 3-7643-6218-9 , page 400.