EN 12390-4: TESTING MACHINES
Machines used to test resistance of hardened concrete to compression are verified in accordance with EN 12390-4 which is part of the set of European Standards EN 12390 and EN 12350 for concrete testing. Verification of the forces is based on two main points:
- The compression force generated by the testing machine on the specimen, the metrological characteristics of which are measured by using a traditional compression load cell previously calibrated and classified according to ISO 376.
- The transfer of compression force to the test specimen. This verification requires a specific compression load cell called a "strain gauge cylinder", the performance of which must be validated beforehand by means of a specific calibration. This type of transducer is included in SENSY’s production range, and some metrological institutes are able to perform the required calibration.
DIN 51302 has virtually disappeared and has been replaced by the new EN 12390-4.
EN12390-4 standard is based on the ratios provided by the compression cylinder to check the homogeneity of force application. It is therefore important that the calibration is based on the same physical quantity. As a reminder, the ratio ri of the bridge i is a unit-less quantity:
With ei as the response to bridge i and
Therefore, calibration of a deformation cylinder comprises applying a standard ratio to which the ratio provided by the deformation cylinder must be compared. Thus, the difficulty with calibration concerns the method of applying a standard ratio to the deformation cylinder. The laboratory with which SENSY works has developed a method of applying a standard ratio and relevant criteria associated with these tests to verify that the deformation cylinder meets the needs of EN12390-4 for verifying the homogeneity of the application of the force by the compression testing machine.
NOTE : Spanish version /en/tecnologia/normas/ensayos-de-hormigon-endurecido-EN-12390-4