Effect of microcracks
CRC beam exposed to chlorides in special rig, where permanent deflection is introduced

Specimens exposed to chlorides
Beams with 3 levels of deflection were exposed

The durability of High Performance Concrete is usually superior to that of conventional concrete, and in the case of CRC the matrix is so dense that there are practically no capillary pores. Measurements show a total porosity of 1.54% and only 14% of this porosity is in the capillary region. This means that there are no freeze/thaw problems, as there is no freezeable water available, and also carbonation proceeds at a very slow rate.

A technical note on durability of CRC can be downloaded from the "documentation" page.

Tests on chloride penetration have been carried out by loading beams in a special rig and then exposing the complete rig to salt water. The bending stresses induced in the beams by the rig can be as high as 75 MPa, but in no cases has corrosion of rebars been observed in the tests, even after exposure for more than 4 years. The cover to the reinforcement was 10 mm in the test beams.

Other tests have been carried out with addition of chlorides to the mixing water (3.2% by weight of cement) or by exposing beams loaded until they show visible cracks, but in these cases as well, no corrosion was observed, as the availability of oxygen and water in this type of concrete with so few capillary pores was not sufficient to initiate corrosion.

Based on these and other tests the cover to the reinforcement in CRC is typically 10-15 mm even in environments with severe chloride concentrations. A note describing the durability of CRC in more detail can be downloaded from the Documentation page.


Article in Concrete Engineering International

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