Tensile behavior of rebar-reinforced coarse aggregate ultra-high performance concrete (R-CA-UHPC) members

Experiments and restrained shrinkage creep effect

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Abstract

Rebar-reinforced coarse aggregate ultra-high-performance concrete (R-CA-UHPC) has been used in the construction of new structures and strengthening of deteriorated aged infrastructures, and it inevitably sustains tension. To study the tensile behavior of R-CA-UHPC members, axial tensile tests for dog-bone-shaped specimens were designed and conducted. The investigated variables included reinforcement ratio in terms of rebar quantity/diameter, and concrete type (CA-UHPC vs. normal concrete). The test results showed that the improved rebar/CA-UHPC bond property prevents the emergence of splitting cracks, but intensifies the crack localization for CA-UHPC and strain concentration for rebar after yielding. Moreover, the restrained effect of rebar on free shrinkage of CA-UHPC leads to a decrease in the first cracking strength for R-CA-UHPC members. Based on the established development functions of elastic modulus, autogenous shrinkage, and tensile creep for CA-UHPC, the restrained effect was quantified according to Dischinger's-differential-equation-based theoretical analysis. Finally, the models to predict the first cracking stresses/strains and the yielding loads of the R-CA-UHPC members were developed and validated.