Compressive Creep Test on Fiber-Reinforced Ultra-High Performance Concrete: Effects of Strain Measuring Method, Specimen Size, Sustained Load Intensity, and Fiber Length

Abstract

To solve the difficulties in applying the compressive creep test method for normal concrete to UHPC and to verify the validity of the recently proposed ASTM C 1856 standard test method, this study performed compressive creep tests on UHPC with the variables of specimen size, sustained load intensity, fiber length, and strain measuring method. The experimental results show that the strain meter method using the standard rod had limitations due to the error in the verification process using the standard rod and the observation error of the measurer, and a sustained load intensity of 15% to 40% of the actual compressive strength is preferable. It was found that it is possible to perform a compressive creep test for UHPC using a specimen with a size of ϕ75 mm or more, and the fiber length did not affect the creep behavior of the UHPC up to 19.5 mm. As a result of comparing the UHPC creep test results with the creep prediction model, the B3 model was found to most accurately predict the UHPC creep behavior. The creep coefficient pattern of the B3 model was very similar to the measured results and well reflects the effects of the mixing ratio and compressive strength of UHPC.