Abstract: The ultra-high toughness cementitious composites (UHTCC) was developed by taking the recycled powder (RP) of construction waste as the substitute of fly ash. The tensile and compressive properties of UHTCC with diverse substitution rates of RP were studied, and the impact of RP on the the mechanical property of UHTCC was explored. Stable strain hardening behavior and multiple cracking responses of RP-UHTCC were obviously observed by axial tensile test. The test results indicated that the tensile strength of RP-UHTCC were about 4—5 MPa (2—3 times of that of ordinary concrete), while the tensile strain capacity reached 7% to 9% (possessing ultra high tensile deformability equivalent to the steel rebar). It indicated that incorporating RP did not change the superior tensile capacity of UHTCC. The axial compressive test showed that the peak compressive strength of RP-UHTCC was about 21 MPa to 23 MPa. The compressive strains corresponding to the 80% peak compressive strength were 18.28‰ and 26.18‰, indicating the high compressive deformation ability of RP-UHTCC. Furthermore, 3-point bending test and single crack tension test were carried out on notched beams and notched dog-bone specimens, respectively, for the sake of studying the effect of the incorporation of RP on the fracture toughness of matrix and bridging ability of fibers. It was found that the fracture toughness of matrix remained unchanged while the bridging ability of fibers increased with the increasing substitution rate of RP. Finally, the explanation and evaluation to the ductility of RP-UHTCC were given by the derived PSH criterion. In this study, the feasibility of recycled powder for producing the ultra-high toughness cementitious composites was verified through experiments.
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2019, Vol. 33 
