Material Properties of Thin UHPC Slabs Used for Timber-Concrete Composite Bridge

Abstract

This paper deals with the material properties of Ultra High Performance Fiber Reinforced Concrete (UHPFRC or UHPC) and especially focuses on bending tests executed for the development of bridge deck segments for an innovative timber-concrete composite bridge system. In the first step, the precast bridge deck segment is designed as a thin slab made of UHPC of a constant thickness, without any ribs and without any reinforcement. Only steel fibres are used as a scattered reinforcement. The bending tests for determining flexural strength of UHPC were executed on the slab strips under similar boundary conditions as by the bridge deck segments. The slab strips of various thickness of 40, 50, 60, 70 and 80 mm were tested in 4-point bending tests with span 1900 mm and in 3-point bending tests with span 600 mm. Half of the test specimens were tested in casting position, other half were tested upside down. The obtained values of the flexural strength were compared with values from reference bending tests of the beams 150 x 150 x 700 mm, 100 x 100 x 400 mm and 40 x 40 x 160 mm. Different size of the tested specimen is discussed. An influence of the positioning of the slab with respect to the direction of casting and the influence of the deck thickness on the flexural strength is evaluated