High Ductile Concrete Research Articles

Composite Properties of High-Strength, High-Ductility Concrete

A new fiber-reinforced cementitious composite—high-strength, high-ductility concrete (HSHDC)—has been developed at the University of Michigan, Ann Arbor, in collaboration with the U.S. Army Engineer Research and Development Center, Vicksburg, MS. The micromechanics-based design of HSHDC resulted in a unique combination of ultra-high compressive strength (166 MPa [24 ksi]), tensile ductility (3.4%), and high specific energy absorption under direct tension (greater than 300 kJ/m3 [6270 lb-ft/ft3]). The material design approach and mechanical property characterization of HSHDC under direct tension, split tension, third-point flexure, and uniaxial compression loading, along with its density and fresh properties, are reported in this paper.

Micromechanics of High-Strength, High-Ductility Concrete

This paper reports the microscale investigation of a new fiber-reinforced cementitious composite, high-strength, high-ductility concrete (HSHDC), which possesses a rare combination of very high compressive strength (166 MPa [24.1 ksi]) and very high tensile ductility (3.4% strain capacity). The investigation involved experimental determination of fiber/matrix interaction properties using single-fiber pullout tests. A new mechanism of inclination-dependent hardening in fiber pullout—unique for a high-strength cementitious matrix—is discovered. The existing fiber-pullout analytical model for strain-hardening cementitious composites (SHCCs) is modified to incorporate the new mechanism. The modeled fiber-pullout behavior is used in a scale-linking model to compute the crack bridging (σ-δ) relation of HSHDC, which is also empirically verified through single-crack tests. The σ-δ relation of HSHDC satisfies the micromechanics-based necessary strength and energy conditions of steady-state flat crack propagation that prevent localized fracture. The microscale investigation of HSHDC in this research thus demonstrates the rational basis for its design combining both high compressive strength and high tensile ductility.