Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Wang, Ruijun; Li, Yan; Xu, Fan; Li, Xiaotong; Fu, Tenghuan

doi:10.1155/2019/8702324

Cited by 4 publications

(8 citation statements)

References 48 publications

(65 reference statements)

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“…В частности, они могут быть востребованы при решении задач определения «оптимальных» параметров внутренней структуры бетонов, функционирующих в условиях влагонасыщения или в водной среде. Другим перспективным приложением, которое заслуживает отдельного упоминания, является оценка механического влияния воды на деградацию поверхностных слоев и износ поверхностных слоев бетонных элементов конструкций в крупных водоемах северных широт, в том числе в условиях арктического климата [12]. Такие опорные бетонные элементы находятся в условиях длительного контактного нагружения протяженными (десятки километров) ледовыми плитами толщиной до 1-2 м. При динамических подвижках ледовых массивов со скоростями до нескольких метров в секунду (например, при «льдотрясениях») локальные давления в пятнах контакта могут кратковременно достигать десятков мегапаскалей и даже превышать величину прочности бетона на одноосное сжатие.…”

Section: Introductionunclassified

The Numerical study of the influence of a two-scale pore structure on the dynamic strength of water-saturated concrete

Konovalenko

Сергеевич²,

Shilko

et al. 2020

PNRPU Mechanics Bulletin

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Many infrastructural concrete facilities, such as dams, bridge footings, foundations of port facilities and offshore drilling platforms, operate in a permanent contact with water. The permeable fractured-porous structure of concrete determines the water-saturated state of the surface layers of such concrete elements. Under dynamic contact loading, the pore fluid is capable of exerting a significant mechanical influence on the local stress-strain state and strength characteristics of the surface layers of concrete. This has to be taken into account when assessing the wear intensity of surface layers and predicting a concrete element’s service life. The aforesaid determines the relevance of the study aimed at identifying the influence of the pore fluid and characteristics of the concrete pore structure on the strength and fracture pattern under quasistatic and dynamic compressive loading. The present work is devoted to the theoretical study and generalization of the laws of mechanical influence of the pore fluid on the dynamic strength of high-strength concrete with a two-scale pore structure. The emphasis in the study is on analyzing the contributions of each of the pore subsystems to the integral mechanical effect of the fluid. To carry out such an analysis, a coupled hydromechanical model is developed. It takes into account the compositional structure of concrete, the presence of a pore space in a cement stone of two different scales, the interaction of a pore liquid and a solid-phase skeleton based on the Bio poroelasticity model, as well as fluid filtration in a pore space. By using the developed model were performed the numerical studies of the dependence between the compressive strength of the representative concrete volumes of the mesoscopic scale on the strain rate, the sample size, the pore fluid viscosity, and pore structure parameters. The simulation results showed the possibility of combining the obtained dependencies into a generalized (master) curve in terms of a combined dimensionless parameter, which has the meaning similar to the Darcy number. We identified two key factors that control the type and parameters of the concrete master curve of the dynamic strength. The first factor is the mobility of the pore fluid in the network of the capillary pores. It determines the rate of stress equalization in the porous skeleton due to fluid flow. The second factor is the interconnection of large micropores with the network of the small capillary pore channels. It determines the magnitude of the decrease in stress concentration in micropores by filtering the excess pore fluid into the capillary pore network. It is shown that the contributions of these two factors to the amplitude of variation of the dynamic strength of the water-saturated concrete are additive, and their total contribution reaches 25 %.

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Section: Introductionunclassified

The Numerical study of the influence of a two-scale pore structure on the dynamic strength of water-saturated concrete

Konovalenko

Сергеевич²,

Shilko

et al. 2020

PNRPU Mechanics Bulletin

View full text Add to dashboard Cite

show abstract

“…At the same time, knowledge of the local (mesoscopic) characteristics of concrete is of most importance in many topical practical problems. Examples of such problems are local contact loading of underwater parts of large concrete structures, including the collision of a ship with a concrete berth or dynamic contact load by ice plates during “icequakes” (analog of earthquakes in ice covers of large northern lakes or seas) [ 38 , 39 , 87 ]. Underestimation of local dynamic strength can have the far-reaching consequence of reducing the operational life of the entire concrete structure.…”

Section: Resultsmentioning

confidence: 99%

Nonlinear Mechanical Effect of Free Water on the Dynamic Compressive Strength and Fracture of High-Strength Concrete

Shilko

Konovalenko

2021

Materials

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It is well-known that the effect of interstitial fluid on the fracture pattern and strength of saturated high-strength concrete is determined by qualitatively different mechanisms at quasi-static and high strain rate loading. This paper shows that the intermediate range of strain rates (10−4 s−1 < ε˙ < 100 s−1) is also characterized by the presence of a peculiar mechanism of interstitial water effect on the concrete fracture and compressive strength. Using computer simulations, we have shown that such a mechanism is the competition of two oppositely directed processes: deformation of the pore space, which leads to an increase in pore pressure; and pore fluid flow. The balance of these processes can be effectively characterized by the Darcy number, which generalizes the notion of strain rate to fluid-saturated material. We have found that the dependence of the compressive strength of high-strength concrete on the Darcy number is a decreasing sigmoid function. The parameters of this function are determined by both low-scale (capillary) and large-scale (microscopic) pore subsystems in a concrete matrix. The capillary pore network determines the phenomenon of strain-rate sensitivity of fluid-saturated concrete and logistic form of the dependence of compressive strength on strain rate. Microporosity controls the actual boundary of the quasi-static loading regime for fluid-saturated samples and determines localized fracture patterns. The results of the study are relevant to the design of special-purpose concretes, as well as the assessment of the limits of safe impacts on concrete structural elements.

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“…F I G U R E 2 2 SEM image of concrete after freezing-thawing cycle and triaxial compression (magnification 1000 times): (a)-(c) strain rate is 1 Â 10 À4 ; (d) 100 cycles with a strain rate of 1 Â 10 À3 . 38 At present, there is little research on the performance of concrete under a water pressure environment. However, with the continuous emergence of hydraulic concrete engineering, it is necessary to master the performance of concrete under a water pressure environment.…”

Section: Freezing and Thawing Cyclementioning

confidence: 99%

“…Researchers 36,37 paid attention to the permeability of ions under water pressure and found that high water pressure significantly increased the penetration depth of ions, resulting in different corrosion rates at different water pressures. Considering freeze–thaw damage of concrete caused by positive temperature in summer and negative temperature in winter, Wang et al 38 conducted dynamic triaxial compression tests on concrete after freeze–thaw cycles under different water pressures to observe microstructure changes and macro performance.…”

Section: Introductionmentioning

confidence: 99%

Evolution characteristics and mechanism of concrete performance under water pressure environment: A comprehensive review

Xue

Tong

Alam

et al. 2023

Structural Concrete

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Compared with the ground service environment, the evolution of concrete performance under a water pressure service environment is quite complex with variable conditions. Because of the coupling effect of load and pressure, water has a special impact on the strength and deformation of concrete. Meanwhile, harmful ions usually react with the cement matrix as pressure water seepages into concrete, resulting in the reduction of concrete durability. Based on this, this study provides a comprehensive review of the strength, deformation, and durability of concrete under water pressure environment. It is found that microcracks in concrete tend to propagate and connect after exposure to water pressure, leading to a decrease in strength and deformation performance. The average loss rate of strength and elastic modulus increased by 12.15% and 10.97%, respectively, when water pressure increased by 1 MPa. However, the loading process of water‐confining pressure makes concrete more compact, where the static and dynamic mechanical performance can be improved. Besides, due to the enhancement of excess pore water pressure, concrete strength under a high strain rate increases by 61.79% compared to static load. The effect of water pressure increases the ability of the liquid to penetrate concrete, and corrosive ions trapped within the liquid and freeze–thaw caused by external temperature changes would further reduce the concrete durability. This study points out that static and dynamic loading characteristics and durability of concrete under multi‐factor coupling in a water pressure environment will be the future research direction. The summarized contents can provide guidance for construction and research of concrete engineering under a water pressure environment.

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Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Cited by 4 publications

References 48 publications

The Numerical study of the influence of a two-scale pore structure on the dynamic strength of water-saturated concrete

The Numerical study of the influence of a two-scale pore structure on the dynamic strength of water-saturated concrete

Nonlinear Mechanical Effect of Free Water on the Dynamic Compressive Strength and Fracture of High-Strength Concrete

Evolution characteristics and mechanism of concrete performance under water pressure environment: A comprehensive review

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