34. Ballistic and Material Tests and Simulations on Ultra-High Performance Concrete

Ultra-high performance concretes (UHPC), meaning concretes with compressive strengths above 150 MPa (B-150), introduce improved properties such as stiffness, compressive strength, and post-failure compliance as compared to standard concretes. Advantages are shown in standard applications of construction, yet, a large potential exists in applications of protective structures to withstand impulsive loadings of blast or direct impact. In this work an UHPC with a compression strength of 200 MPa was used to test and develop a material model to enable predictions for impact and penetration. The material was first tested to characterize the material behavior under quasistatic loading in torsion, compression and triaxial compression, up to confinement pressures of 500 MPa. Moreover, the UHPC was characterized under dynamic loading, using a Kolsky bar (Split Hopkinson Pressure Bar). Based on these lab-scale tests, a Johnson-Holmquist material model was calibrated for the numerical simulations. Finally, ballistic tests were performed with two projectile geometries, using two configurations: a standalone UHPC panel to obtain the ballistic limit, and depth of penetration (DOP) measurements, with aluminum backing, to better relate to the concrete strength during penetration conditions. Preliminary ballistic computations with the UHPC model, calibrated from the lab-scale tests for LS-DYNA, provided good predictions when compared to most of the tests.