In addition to strength and visual properties, durability is the essential criterion for concrete products used in road and traffic route construction. Concrete pavers and kerbstones are exposed to natural weather conditions and - in areas subject to traffic and foot traffic - to the sometimes very intensive physical attack of frost and de-icing salt during their entire service life, which is generally at least 30 years.

In contrast to normal concrete according to DIN 1045-2, there are no descriptive specifications for the concrete compositions of concrete products for traffic route construction made of so-called "earth-moist concrete", which, if observed, can be assumed with sufficient certainty to have a high resistance to freeze-thaw and de-icing salt. Various test methods have been developed in recent years for the rapid assessment of the freeze-thaw resistance of concrete components. The standards DIN EN 1338 and DIN EN 1340 provide for the so-called "slab test" to prove the sufficient frost resistance of class 3. In addition, the so-called CDF method is still frequently required today, especially by the main customers - the public road construction authorities, sometimes in addition to the slab test as quality assurance. Both methods stress the test specimens with different intensities during the test, so that the same concretes usually also show significantly - up to 10-fold - different levels of weathering.

The object of this research project is therefore to answer the currently open question of the extent to which the test results obtained with the two currently common freeze-thaw laboratory test methods actually reproducibly reflect the behavior of concrete products and paving stones to be expected in practice and - if this should not be the case - how the test methods may have to be adapted. The suitability of a test method is ultimately based on whether it succeeds in accelerating the relevant damage mechanisms occurring in practice and thereby arriving at an evaluation that corresponds to the long-term behavior in practice. This has not been clarified with regard to testing the freeze-thaw resistance of concrete products made of earth-moist concrete and, in particular, for two-layer concrete pavers made of different core and facing concretes.