Experimental Testing of Resistance of Ultra-high Performance Concrete to Environmental Loads

Ultra-high performance concretes (UHPC) are characterized by high tensile and compressive strength. The high strength is achieved by providing well-graded grain-size distribution curve and by utilization of microfillers. The dense structure of UHPC provides low permeability, which increases resistance of high-performance concrete to aggressive chemical solutions or freeze-thaw cycling. Both these features positively affect the possibilities of utilization of high-performance concrete for outdoor structures. The paper presents the first findings of comprehensive research program focused on the investigation of resistance of UHPC to deicing chemical agents and freeze-thaw cycles. Several series of tests were conducted to compare the behavior of UHPC and reference C40/50 class fibre-reinforced concrete. Several dozen specimens were tested, various load levels were applied. The results have shown that up to certain number of freeze-thaw cycles, the mechanical properties of UHPC are not affected at all. A hypothesis is proposed to explain this outcome of the experiments.