Testing and analysing innovative design of UHPFRC anchor blocks for post-tensioning tendons

Experimental validation of innovative design of anchor blocks for post-tensioning tendons was carried out. The tested specimens were made of UHPFRC, namely Ductal® -FM for 9 blocks and BSI® for 3 other blocks, and did not contain any passive reinforcement normally provided for confining concrete submitted to localized compression, and preventing bursting. They were dedicated to 4T15S, 7T15S and 12T15S pre-stressing units. Splitting in the middle of block sides, leading to sub-vertical cracks, appears as the dominant critical mechanism. Depending on lateral dimensions of UHPFRC around the reservation, and possible size effects concerning this zone submitted to intense tensile stresses, the maximum load has been obtained from 1,2 to 2,2 times the ultimate force of the tendons F prg , with a typical scatter about ± 10%. While refinements remain possible for optimizing the safety margin depending on project requirements, obtained results validate the innovative (reinforcement-free) design and typical dimensions of these UHPFRC anchor blocks.