The report describes experiences from the use of a material model for concrete #72 "Concrete Damage", available in the material model library in the FE-code LS-DYNA ver. 950. This is release I of of the K&C concrete model. The study is limited to the modelling and simulation of concrete slabs in two experiment series, where the concrete slabs had different material properties, but were subjected to the same detonation load in a shock tube. The experiments were reported earlier and numerical simulations were performed with LSDYNA, DYNA and ABAQUS with other material models. The results from the simulations have not shown acceptable agreement with the results from the experiments. The reason according to the developers is that the Prandtl-Reuss flow rule, applied in Release I does not induce volume changes at shear failure and thus does not admit the development of large enough membrane compression stresses. In conclusion it may be stated that the model in the form it is implemented in the standard library of LSDYNA ver. 950 is not suitable for predicting the response of in-plane restrained slabs subjected to blast loads. This conclusion is confirmed from the fact that changes of the model have been performed by the developers that will cure the problem in Release II and Release III. Those versions are not yet implemented in the material library of LS-DYNA.