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Micro-structure and Macro-performance:Surface Layer Evolution of Concrete under Long-term Exposure in Harsh Plateau Climate

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Journal of Wuhan University of Technology(Materials Science) 2024年第6期39卷 1496-1506页

作者： CHEN Xin CUI Anqi ZHENG Haitao YANG Wencui HUANG Xin GE Yong LI Lihui School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China Zhengzhou Engineering Co. Ltd of China Railway Seventh GroupZhengzhou 450052China Research Institute of Highway Ministry of Transport Beijing 100088China

We conducted a series tests on surface layers of plateau concrete at the ages of 180 and 540 days,including the most superficial cement paste,the 5 mm thick surface mortar,and the 50 mm thick surface *** and nitrogen absorption porosimetry on cement past,mercury intrusion porosimetry on mortar,and microhardness test on interface transition zone between mortar and coarse aggregate were conducted to evaluate the hydration degree and characterize the ***,tests for the rebound strength,abrasion resistance,and chloride ion impenetrability of concrete were conducted to assess the *** experimental results show that,affected by the harsh plateau climate,outward surfaces have lower hydration degrees and worse pore structure than inward *** the hydration of concrete surface is ongoing after the age of 180 days,both the micro-structure and the macro-performance are continuously *** the long-term,either the orientation or the depth towards surface does not significantly affect concrete *** carbonation brings positive effects on mechanical properties but negative effects on the ***,standard test result of chloride ion impenetrability is found significantly affected by the atmospheric *** a same batch of concrete,charge passed in plateau regions is obviously lower than that in common regions.

关键词： concrete pore structure interface transition zone mechanical property chloride ion impenetrability plateau

Effect of Randomness of Interfacial Properties on Fracture Behavior of Concrete Under Uniaxial Tension

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Acta Mechanica Solida Sinica 2018年第2期31卷 174-186页

作者： Chuanchuan Zhang Xinhua Yang Hu Gao School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan 430074 China

Interfacial transition zones （ITZs） between aggregates and mortar are the weakest parts in concrete. The random aggregate generation and packing algorithm was utilized to create a two-phase concrete model, and the zero-thickness cohesive elements with different normal distribution parameters were used to model the ITZs with random mechanical properties. A number of uniaxial tension-induced fracture simulations were carried out, and the effects of the random parameters on the fracture behavior of concrete were statistically analyzed. The results show that, different from the dissipated fracture energy, the peak load of concrete does not always obey a normal distribution, when the elastic stiffness, tensile strength, or fracture energy of ITZs is normally distributed. The tensile strength of the ITZs has a significant effect on the fracture behavior of concrete, and its large standard deviation leads to obvious diversity of the fracture path in both location and shape.

关键词： interface transition zone Random parameter Concrete Fracture

Meso-scale corrosion expansion cracking of ribbed reinforced concrete based on a 3D random aggregate model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2021年第11期22卷 924-940页

作者： Zhi-qiang ZHANG Yong-long LI Xing-yu ZHU Xin-hua LIU School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China

In reinforced concrete structures,corrosion of the rebar produces 2–6 times more corrosion product than the original material,creating pressure on the surrounding concrete,leading to *** study of corrosion and cracking in reinforced concrete structures is therefore of great importance for enhancing the durability of *** many previous studies,we used ribbed rebar similar to that used commercially and considered the mechanical behavior of the interface transition zone(ITZ)between the aggregate and mortar to simulate the processes of corrosion and cracking of reinforced concrete *** explored the failure mode of the interface layer under uniform corrosion and the influence of different factors on the corrosion expansion cracking and the shedding mode of a concrete *** was achieved by establishing a three-phase meso-scale model of concrete based on secondary development of ABAQUS,simulating the mechanical behavior of the ITZ using a cohesive element,and establishing a rust expansion cracking model for single and multiple *** results showed that:(1)Under uniform rust expansion,concrete cracks are distributed in a cross pattern with a slightly shorter lower limb.(2)When the corrosion rate is low,the ITZ is not *** an increase in the corrosion rate,the proportion of elements with tensile damage in the ITZ first increases and then decreases.(3)In the case of a single rebar,the larger the cover thickness,the higher the corrosion rate corresponding to ITZ failure,and the arrangement of the rebar has little influence on the ITZ failure mode.(4)In the case of multiple rebars,the concrete cover cracks when the rebar spacing is small,and wedge-shaped spalling occurs when the spacing is large.

关键词： Rebar corrosion 3D meso-scale model Cohesion model interface transition zone Failure mode

The interface Structure of High Performance Expansive Concrete (HPEC)

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The Interface Structure of High Performance Expansive Concre...