Abstract

This study investigated the material properties of air-cured ultra-high-performance fiber-reinforced concrete (UHPFRC) at early ages. To assess the material properties of UHPFRC at early ages, compressive and three-point bending tests were respectively performed at the 10 stages of early ages on ø 100 × 200 mm cylinders and 100 × 100 × 400 mm specimens made from UHPFRC with a 2% steel fiber volume ratio. Based on the regression analysis of the compressive and flexural test results for each age, model equations were proposed that can predict the compression strength, modulus of elasticity and flexural strength at early ages. In addition, to determine the tensile softening curves of UHPFRC at early ages, the inverse finite element (FE) analysis was applied using the poly-approximation method; based on the results, model equations are presented that can predict the tensile softening curve. The load-variable curves obtained from the simulation using the proposed tensile softening model fit the measurements from the flexural tests relatively well.

Key words: UHPFRC, air curing, material property, tensile softening, early age.