Early age and durability study of the bond strength on the interface between UHPC – HSC
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Date
2021-10
Authors
Tan, Li Xin
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Abstract
This thesis explores the bond performance of the interface between UHPC and high strength concrete. The aim of the experimental work is to define some of the transverse shear transfer parameters, such as the cohesion and friction coefficient at the interface between the shear key filler material and adjacent precast box beams on bridge design.
The four test methods used to quantify the short- and long-term bond performance include the direct tension, pull off, slant shear and bi-shear tests. The study emphasizes on evaluating the interfacial bond performance between the materials using small-scale specimens. The variables in the experiments consist of the age of UHPC, the exposure to the freeze-thaw cycles as well as number of cyclic loadings. A total of five interface parameters were evaluated, namely, the roughness average, mean texture depth, mean profile depth, true surface area and interfacial area ratio on direct tension test specimens. The Mohr-Coulomb’s and Carol’s approaches were adopted to construct the failure envelope and the experimental results were subsequently used to estimate the cohesion and friction coefficients at the bond interface.
The overall interface bond performance of the small-scale specimens was satisfactory. The direct tensile and slant shear strength exceeded the minimum bond strength as specified in ACI 546 (2006). The correlation between the interface parameters, modes of failure and direct tensile strength showed mixed results. Further research will be needed to establish the relationship between the variables.
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Keywords
UHPC, Early Age, Durability, Bond Strength, Cohesion and Friction Coefficients, Tensile, Compression and Shear, Shear