Experimental field investigation of impact and blast load resistance of Ultra High Performance Fibre Reinforced Cementitious Composites (UHPFRCCs)

• UHP-CY slabs have an excellent performance against blast and impact.
• A purpose-built experimental setup was developed.
• Relatively thin slabs can prevent the penetration of missiles without shaped charge.
• Can also minimise the damage of structures hit by missiles with shaped charge.
• Spalling and fragmentation is controlled by the use of steel fibres.

Ultra High Performance Fibre Reinforced Cementitious Composites (UHPFRCCs) represent a class of cement composites which have superior characteristics in terms of material properties. These materials have, however, a significant increase in cost compared to conventional and even High Performance Concrete and it is therefore appropriate to identify applications which will fully utilise their mechanical properties and performance characteristics. A new class of UHPFRCC material has been developed through the experimental work of a research project entitled “Mix Design, Mechanical Properties and Impact Resistance of UHPFRCCs”, designated UHP-CY. The material is characterised by high compressive strength, high tensile/flexural strength and high-energy absorption capacity. The research work presented in this paper focused on the experimental investigation of the quality and the behaviour of this material in a highly demanding application, such as the impact and blast resistance of structures. The impact resistance of UHP-CY slabs was experimentally verified in a range of real firing shots, using several weapons and projectile types. A purpose-built experimental setup was developed for this work. It was observed that relatively thin slabs made of this material can be an outstanding protective overlay of existing structures, since they can prevent the penetration of strong projectiles without shaped charges. Moreover, these panels can also minimise the damage of retrofitted Reinforced Concrete structures, hit by projectiles with shaped charges. The presence of a high volume fraction (i.e. 6%) of steel fibres in UHP-CY overlays contributes substantially to the control of the back face spalling and fragmentation of the RC walls.