LAUSR

Abstract The development of formwork pressure is essentially affected by the rheological behavior of fresh concrete, while the shear behavior itself might be influenced by the magnitude of normal pressure. A test set-up was developed in which the fresh mortar and concrete can be sheared in a pressure cell by a vane as a part of a concrete rheometer (ICAR). The concrete is directly loaded in the pressure cell by a hydraulic jack. Preliminary shear tests were conducted on concretes with moderate and high flowability at constant water/binder-ratio of 0.4 with the focus on the static yield stress. The additional pressure was applied up to 240 kPa. The consistency class of the concrete F4, F5 and F6 was varied by choosing the paste volume to 300, 315 and 330 l/m3, respectively. The results show the significant influence of applied pressure on the measured yield torque or yield stress in early concrete age especially for concretes with moderate flowability (F4) or with relatively high volume fraction of aggregates respectively. However, a significant increase of yield resistance by applied pressure was identified for all concretes after 90 min concrete age.