|The Eurocode classifies HSC into three classes*, depending on its compressive strength, namely, |
(i) class 1 for concrete with compressive strength between C55/67 and C60/75,
(ii) class 2 for concrete with compressive strength between C70/85 and C80/95,
(iii) class 3 for concrete with compressive strength higher than C90/105.
The strength notation of C55/67 refers to a concrete grade with a characteristic cylinder and cube strength of 55 N/mm2 and 67 N/mm2, respectively.
*Note: where the actual characteristic strength of concrete is likely to be of a higher class than that specified in the design; the relative reduction in strength for the higher class should be used for fire design.