Research

Experimental centre (EC) is dealing with development and testing of Ultra-High Performance Fibre-Reinforced Concrete. UHPFRC is becoming very vibrant and active so its utilization in the protective structures is nowadays dynamically promoted. UHPFRC can be classified as cementitious composites with very low water to binder ratio, enormous amounts of high-range water reducers (HRWR), aggregates with a maximum grain size of less than 1 mm and fibre reinforcement in the form of high-strength steel fibres. Such material provides the structure with essential resistance while maintaining its standard thickness and appearance, because it has much greater ability to dissipate energy and absorbs force impulses.

UHPFRC is a concrete with dense microstructure which naturally leads to excellent environmental resistance. Its natural property is the self-compactibility and typically very high strengths are achieved in the early age during the hardening process. UHPFRC developed in EC exceeds the uniaxial compressive strength of 150 MPa and tensile strength is in the range of 10 MPa. UHPFRC is tested on series of shock loading using impact pendulum acting with an impact speed of 5 m/s. Data acquisition system for impact behaviour assessment is set with 1MHz sampling frequency. Furthermore, the UHPFRC is subjected to series of projectile impact tests. This simulated direct armed attack or high-speed generated fragment with impact velocity of 700 m/s.

Numerical analysis of the impact phenomena is carried out in AUTODYN software, which is well suited for the simulation of such extreme dynamic loads running at high speeds and over a short time period. Detailed models of the experiments are constructed using the mesh and meshfree methods in both 2D and 3D. Besides, material models for UHPFRC are constructed using experimentally established mechanical properties.