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Flexural behavior of ultra high performance concrete beams reinforced with high strength steel
Jun-Yan Wang,Jin-Ben Gu,Chao Liu,Yu-Hao Huang,Ru-Cheng Xiao,Biao Ma 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.5
A detailed experimental program was conducted to investigate the flexural behavior of ultra high performance concrete (UHPC) beams reinforced with high strength steel (HSS) rebars with a specified yield strength of 600 MPa via direct tensile test and monotonic four-point bending test. First, two sets of direct tensile test specimens, with the same reinforcement ratio but different yield strength of reinforcement, were fabricated and tested. Subsequently, six simply supported beams, including two plain UHPC beams and four reinforced UHPC beams, were prepared and tested under four-point bending load. The results showed that the balanced-reinforced UHPC beams reinforced with HSS rebars could improve the ultimate loadbearing capacity, deformation capacity, ductility properties, etc. more effectively owing to interaction between high strength of HSS rebar and strain-hardening characteristic of UHPC. In addition, the UHPC with steel rebars kept strain compatibility prior to the yielding of the steel rebar, further satisfied the plane-section assumption. Most importantly, the crack pattern of the UHPC beam reinforced with HSS rebars was prone to transform from single main crack failure corresponding to the normal-strength steel, to multiple main cracks failure under the condition of balanced-reinforced failure, which validated by the conclusion of direct tensile tests cooperated with acoustic emission (AE) source locating technique as well.
Qing Hua Zhang,Rui Sheng,Zhao Hua Ren,Jing Huang,Yun Xiao Wang,Ben Ru Wang,Xi Lei Huang,Qin Cheng,Xue Mei Wu,Tong Bo Wang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-
The micellization and the molecular interaction behaviors for two ternary mixtures constituted by anamphoteric sodium 3-(n-dodecyl ethylenediamino)-2-hydroxypropyl sulfonate (C12AS), an anionicsodium dodecylbenzene sulfonate (SDBS) and a nonionic octylphenol polyoxyethylated ether with thenumber (n) of oxyethylene glycol ethers OP-n (n = 10 or 7) in aqueous solution were investigated usingthe tensiometry and the effect of hydrophilicity on them was also discussed. In the framework of pseudophaseseparation model and based on the regular solution theory, the related micellization parametersincluding the mixed critical micelle concentration (cmc) values in the ideal and real cases, the activitycoefficients and the compositions in mixed micelle, etc. and thermodynamic parameters were estimatedby the Clint’s model and the Rubingh’ model. The mixed cmc value is dependent on the composition inaqueous solution and influenced by the hydrophilicity of nonionic surfactant. With increasing the nonionicin ternary mixture, the mixed cmc value is initially decreased and then slightly rise. An increasingin the hydrophilicity of nonionic will make the minimum value of mixed cmc be increased from1.299 mM to 1.705 mM. The resulting phenomena can be explained reasonably by the electrostatic effect,the steric hindrance, the hydrogen bonding, etc. Thermodynamic data indicate that the contribution ofentropy or enthalpy plays a vital role on the spontaneous process of micellization and the share ofentropy or enthalpy in free energy change is dependent largely on the amount of nonionic surfactantand the hydrophilicity. In ternary mixtures of C12AS/SDBS/OP-10, an increase in an amount of OP-10 willinduce the change from the enthalpy-driven micellization process to the entropically favorable process. Once an abundant amount of OP-7 is added, while, the enthalpy will make a main contribution on themicellization process, which can be described by the drop in the share of entropy at the composition(0.6970/0.0000/0.3030) of ternary mixture from 0.6478 to 0.4901. These findings will help with understandingthe molecular interaction behavior for the ternary surfactant mixture and the effect of the additionof nonionic surfactant and its hydrophilicity.