Impact resistance of ultra-high-performance concrete retrofitted with polyurethane grout material: Experimental investigation and statistical analysis

Abstract

The brittle nature of ultra-high-performance concrete (UHPC) increased with strength and is regarded as a shortcoming in structural applications, particularly in regions prone to seismic incidents. To overcome the inherent brittleness of UHPC. This study evaluates the impact resistance of UHPC retrofitted with polyurethane (PU) grouting overlaid using a drop weight of 1.25 kg. Three different overlaid thicknesses, including 5 mm, 10 mm, and 15 mm, were cast on the top surface of U-shaped UHPC specimens. In addition, statistical analysis was performed on the impact resistance data. The results showed that PU grouting overlaid cast on the top of a U-shaped UHPC specimen has significantly improved the impact strength and energy absorption capacity of the UHPC. The improved impact resistance increases with PU grouting overlaid thickness. Due to the brittle nature of UHPC, the first crack strength in the reference UHPC occurred with only 1 to 2 blows. The average number of cracking blows at the failure stage of the UHPC-10 and UHPC-15PU is 381.42% and 1466.5% higher than that of UHPC-5PU, respectively. The crack propagation was controlled using a U-shaped specimen. The coefficient of variation of 18.46% to 41.63% was obtained in this study, which is lower than values obtained in the previous studies adopting the ACI 544-2R testing procedure. The U-shaped UHPC-PU specimen impact resistance data followed the probability function for the two-parameter Weibull distribution, and the reliability analysis result was consistent with the experimental result.