Positive Influence of the Steel Fibres on the Crater Formation of the Steel Fibre Reinforced Concrete Slabs Under Contact Detonation

The number and intensity of attacks has steadily increased worldwide in recent years, requiring more effective building protection elements and structures to minimise the personal injury and anticipated economic damage. Threats that can be expected to affect structural protection systems include bullets from standard firearms, explosions from explosives, vehicle impacts, etc. Targets of attack are not only military and government facilities, but also civilian and industrial facilities, such as those providing essential services, which should be specially protected. In order to ensure the protection of critical infrastructure, the Institute of Structural Engineering, Chair of Concrete Construction at the University of the Federal Armed Forces in Munich is investigating the use of steel fibre concrete as a protective material during reinforcement work on the above structures. As part of this investigation, various reinforced concrete and fibre reinforced concrete slabs of concrete grade C40/50 with different fibre contents (0, 0.5, 1.0 and 2.0 vol%) were produced and subjected to contact detonation with a variable charge (SEMTEX10). After detonation, the plates were scanned using 3D hand scanners (Zeiss systems). The 3D plates were first meshed from the point cloud and visually detectable damage parameters (craters/bursts) were determined using Geomagic-Design X software. Missing crater geometry, damage area, flaking depth, volume and weight of flakes could be accurately displayed and determined. By comparing the results obtained, a positive influence of the steel fibres on the damage to the concrete slabs could be demonstrated. The article presents the results of the tests carried out and the evaluation of the parameters described above.