J. Phys. IV France
Volume 134, August 2006
EURODYMAT 2006 - 8th International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading
Page(s) 701 - 706
Publié en ligne 26 juillet 2006
EURODYMAT 2006 - 8th International Conference on Mehanical and Physical Behaviour of Materials under Dynamic Loading
J. Cirne, R. Dormeval, et al.
J. Phys. IV France 134 (2006) 701-706

DOI: 10.1051/jp4:2006134108

A new Hopkinson bar method to investigate the compacting behaviour of fresh concrete

S. Pattofatto, H. Zhao and A. Poitou

Laboratoire de Mécanique et Technologie, ENS de Cachan, UPMC, 61 avenue de Président Wilson, 94235 Cachan Cedex, France

Published online: 26 July 2006

A new experimental test, based on the Hopkinson bar measurement technique is used in order to analyze the compaction process of a fresh concrete under successive impacts. The use of this modified Hopkinson bar technique allows for the measurement of the compacting stresses during one impact. In fact, the measurement device allows to measure the stress/time response of the material during each shock independently. In particular, the study is focused on the analysis of the stress/time curve during the first shock on the freshly-mixed concrete specimen. It happens that the stress response exhibits the occurrence of the equivalent of a phase change for the granular material. It is therefore possible to measure at what moment this phenomenon happens. Then, we show that, considering a model of shock front for the propagation of the compacting wave, the phase change occurs at a density that depends on the impact velocity. The results shows that the increase of the impact velocity leads to an increase of the phase change density.

© EDP Sciences 2006