Mindestbewehrung zur Begrenzung der Rissbreiten in Stahlbetonbauteilen infolge des Hydratationsprozesses

Minimum Reinforcement to Crack Control in Hardening Concrete Members. Part 2: New concept on base of deformation compatibility

Hydration induced restraint forces can lead to crack formation in hardening concrete members. Securing serviceability and durability of the construction crack widths has to be limited according to exposition class. For this actual standards use the concept of the cracking force. This approach is not free from failings, especially for thick concrete members. The new approach introduced in this article is based on the deformation compatibility and abolishes those failures. The authoritative of this concept is the absorption of the impacting deformation, not the time of crack formation as in the former approach. Thus essential parameters of concrete technology as heat development and curing can be considered quantitative. Furthermore the superposition of early restraint and restraint forces in the use period can be analysed on a common mechanic base. These new findings are the base of the new technical report "Early Restraint" of the Federal Waterways Engineering and Research Institute.