Production and testing of thin-walled UHPFRC precast elements

The use of ultra-high-performance fiberreinforced concrete (UHPFRC) in segmental construction makes it possible to combine various benefits in terms of both materials and processes. Due to its high compressive strength and durability, UHPFRC is the right choice to produce exceedingly thin-walled, sustainable structural components that consume a small amount of materials; segmental construction, in turn, enables the prefabrication of complex structural frameworks within an extremely short period, irrespective of the weather. To investigate this method, a DFG research project was conducted at the Department of Concrete Structures at iBMB, Braunschweig University of Technology, to evaluate the production and load-bearing behavior of thin-walled, precast segmental and monolithic boxsection elements consisting of ultra-high-performance fiber-reinforced concrete (UHPFRC). A fine-aggregate concrete mix was used to produce the specimens at the Rekers precast plant in Spelle. Due to the thin walls of the precast elements and the characteristics of UHPFRC, a tailored formwork and concrete pouring concept had to be developed to enable the safe and accurate production of the thin-walled precast UHPFRC components. The test specimens and segments were delivered by truck to the iBMB in Braunschweig, prestressed and tested on a specially designed test rig both under pure torsion and under combined bending, shear and torsion. All beams showed a sudden concrete compression failure pattern. A design method was developed on the basis of the test results. The findings of this research project open up the opportunity to efficiently produce and apply thin-walled precast elements made from UHPFRC.