chapter  6
Structural materials
Pages 38

Normal concrete is characterized by the letter C followed by two figures that express the characteristic (5%) cylinder strength fck and the cube strength fck,cube at 28 days. Accordingly, C35/45 is a concrete with fck = 35 MPa and fck,cube = 45 MPa. In composite bridges designed by Eurocode 4-2, concrete of strength classes between C20/25 and C60/75 should be used. However, the most usual strength class of the concrete slab is C35/45. The properties of normal concrete are given in Table 6.1, where the aforementioned strength class is shown in italic face [6.3].