Experimental investigation on permanent UHPC formwork based on the axial compression test on the concrete core of NSC-UHPC columns

Abstract

The paper aims to present the test results of circular ultra-high performance concrete (UHPC) formworks filled inside by normal strength concrete (NSC) without steel reinforcements, called NSCUHPC columns. Several UHPC formworks were produced to fill NSC inside. Three steel fiber volume fractions, including 0%, 1%, and 2%, were added to the UHPC mixture. The material strengths were tested on the cylinder samples under concentric loading, and the NSC-UHPC columns were compressed on the NSC core. The test results indicated that the ultimate loads of the columns, confined by UHPC formworks adding steel fibers, are significantly increased. Besides, the effect of UHPC thickness and steel fiber volume fractions on the strength enhancement was clarified. It is recommended that UHPC is a potential material to produce permanent formwork for casting onsite the normal strength concrete.

Keywords: UH; steel fibers; composite columns; UHPC formwork.