Effect of crack opening on the local diffusion of chloride in inert materials

Ismail, Mohammad; Toumi, Ahmed; François, Raoul; Gagné, Richard

doi:10.1016/j.cemconres.2003.10.025

Cited by 93 publications

(44 citation statements)

References 4 publications

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“…In the simulation model of Takewaka et al (2003), if W cr is less than 50μm, the cracks seldom affect diffusivity, but when the W cr is between 50μm and 100μm, D cr was set 10 times of sound part (1×10 -12 m 2 /s), and when W cr is larger than 100μm, D cr was set as 10 3 times. Other experimental results indicate that no significant chloride diffusion occurs in cracks having an opening (crack width) below a critical value, which is approximately 30μm (Francois et al 2005;Ismail et al 2004).…”

Section: Review Of Previous Studiesmentioning

confidence: 99%

Simulation of Chloride Diffusivity for Cracked Concrete Based on RBSM and Truss Network Model

Wang

Soda²,

Ueda

2008

ACT

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For concrete structures exposed to salt environment, the microstructure and cracks play a crucial role in the ingress of chloride ions into concrete. In this study, concrete is simulated on the meso scale as a three-phase composite, i.e., aggregate particles, mortar and the interfacial transition zone (ITZ). Because of the advantages in predicting cracks behavior in concrete, Rigid Body Spring Model (RBSM) is employed to carry out the mechanical analysis to simulate the distribution and width of microcracks. And then, the truss network model is adopted to evaluate the chloride diffusivity of the cracked concrete. On the basis of the statistics analysis of diffusion coefficients of concrete and mortar determined experimentally, the diffusivity of ITZ is analytically clarified. The range of diffusion coefficient of ITZ estimated in this paper is approximately 3-16 times of that of mortar depending on the different assumed thickness, which agrees well with that of the previous experimental results. With the aim to validate the effect of microcracks on the diffusivity of concrete, a series of the chloride ions penetrating analysis is numerically carried out on the concrete specimen under different stress levels. The axial compressive and tensile loading conditions are investigated respectively and the effects of stress level on chloride diffusivity of cracked concrete are examined. Results indicate that the chloride diffusivity is significantly dependent on the stress level, but only considering the effect of cracks predicted by RBSM is not sufficient. So an empirical equation which can account for the microstructure variation of concrete under loading is proposed. With it, a reasonable estimation for chloride diffusivity of cracked concrete is achieved.

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Section: Review Of Previous Studiesmentioning

confidence: 99%

Simulation of Chloride Diffusivity for Cracked Concrete Based on RBSM and Truss Network Model

Wang

Soda²,

Ueda

2008

ACT

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“…Their test results indicated that the rate of chloride penetration perpendicular to the crack surface was very similar to that from the exposed surface when w cr was larger than the critical crack width. The critical crack width is considered as a material property and generally in a range of 50-80 μm according to different tested materials and test methods, whose crack surfaces are completely separated and no stress can be transferred any longer (Ismail et al 2004). This finding can be understood that chlorides penetrate through the crack with a very high rate, even faster than that in free bulk water when crack width is greater than the critical value.…”

Section: Introductionmentioning

confidence: 75%

“…In the simulation model of Takewaka et al (2003), if w cr is less than 50μm, the cracks seldom affect diffusivity, but when w cr is between 50 μm and 100 μm, D cr was set 10 times of the sound part, and when w cr is larger than 100 μm, D cr was set as 10 3 times of that of the sound part. Ismail et al (2004;, and Rodriguez and Hooton (2003) separately examined the penetration property of chlorides through an artificially formed crack, as well as the diffusion speed perpendicular to the crack surface. Their test results indicated that the rate of chloride penetration perpendicular to the crack surface was very similar to that from the exposed surface when w cr was larger than the critical crack width.…”

Section: Introductionmentioning

confidence: 99%

“…In the past, most previous works focused on experimental methods to evaluate the effect of cracking on the chloride diffusion property of concrete, as well as the diffusion features of chlorides in a single crack (Aldea et al 1999;Samaha and Hover 1992;Gowripalan et al 2000;Ismail et al 2004Ismail et al , 2008Rodriguez and Hooton 2003;Kim et al 2010). In the tests, cracks were created naturally by loading a specimen or artificially formatted by cutting the specimen.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mesoscale Modelling of the Chloride Diffusion in Cracks and Cracked Concrete

Wang

Ueda

2011

ACT

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In service, cracks or microcracks are usually present in concrete as a result of several mechanisms, for example the drying shrinkage, thermal gradients, freezing-thawing cycles, alkali-aggregate reaction and external loading. It has been realized that cracking can significantly accelerate the ingress of chlorides into concrete since it provides preferential flow channels and allow more chlorides to penetrate. But it is also believed that cracking plays an important role on the penetration speed of chloride. The objective of this paper is to quantify the diffusion coefficient of chloride through cracks of concrete with different crack widths by means of the mesoscale modelling method based on the available experimental results from literatures. In the numerical models, the position and opening width of cracks are artificially prescribed based on geometrical layout of the samples used in test. Additionally, the Voronoi diagram technique is adopted to discrete the domain of a specimen in order to reduce the mesh bias. On the Voronoi diagram, a randomly distributed lattice network is constructed to represent the transport process of chlorides. The range of investigated crack width is from 20 to 600 μm covering the data in experimental program. The diffusion coefficients of chloride through cracks of different width, D cr , are numerically determined by the trial and error method. It is concluded that chloride can penetrate into cracks with a much higher speed than that in free water. When the crack width is lager than a critical value, D cr is determined as 10000 mm 2 /h and independent of the crack width.

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“…Previous researchers have investigated the necessary conditions for autogenous healing in concrete materials. These studies had resulted in identifying three general criteria critical to robust self-healing: the presence of specific chemical species (7,25,26), exposure to various environmental conditions (9,(26)(27)(28) , and small crack width (9,25,29,30). Meanwhile, it was reported that there were several processes including chemical, physical and mechanical interactions as discussed by Kishi et al (31) to be responsible for autogenous healing.…”

Section: Durability Improved By Self-healing Actionmentioning

confidence: 99%

Overview of recent work on self-healing in cementitious materials

Lv¹,

Chen²

2014

Mater. construcc.

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ABSTRACT:Cracks, especially microcracks, in concrete are of paramount importance to the durability and the service life of cementitious composite. However, the self-healing technology, including autogenous healing and autonomous healing, is expected to be one of effective tools to overcome this boring problem. In this paper, we focus on the autogenous healing of concrete material and a few of recent works of autonomous healing are also mentioned. The durability and the mechanical properties improved by the self-healing phenomenon are reviewed from experimental investigation and practical experience. Several aspects of researches, such as autogenous healing capability of an innovative concrete incorporated geo-materials, self-healing of engineered cementitious composite and fire-damaged concrete, effect of mineral and admixtures on mechanism and efficiency of self-healing concrete are summarized to evaluate the presented progresses in the past several years and to outline the perspective for the further developments. Moreover, a special emphasis is given on the analytical models and computer simulation method of the researches of self-healing in cementitious materials. RESUMEN: Panorámica de trabajos recientes sobre materiales cementantes autorreparables.Las fisuras, y sobre todo las microfisuras, tienen una gran repercusión en la durabilidad y en la vida útil de los materiales cementantes. Ante este problema, la tecnología de la autorreparación, tanto autógena como autónoma, se presenta como una solución eficaz. El artículo se centra en la reparación autógena del hormigón, así como en algunos trabajos recientes sobre la reparación autónoma. Se describen las mejoras de las propiedades de durabilidad y de resistencia que proporciona la técnica del hormigón autorreparable, tanto desde el punto de vista de la investigación experimental como del de la experiencia práctica. A fin de evaluar los avances logrados en los últimos años y de trazar las grandes líneas de desarrollo futuro, se resumen varios de los aspectos investigados: capacidad de reparación de un hormigón innovador que incorpora geomateriales; autorreparabilidad tanto de los compuestos cementantes tecnológicos como de los hormigones que han sufrido daños por incendio; influencia de los aditivos minerales en el mecanismo y eficacia del hormigón autorreparable. Además, se destaca el papel de los modelos analíticos y los métodos de simulación informática en la investigación de los materiales cementantes autorreparables.

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Effect of crack opening on the local diffusion of chloride in inert materials

Cited by 93 publications

References 4 publications

Simulation of Chloride Diffusivity for Cracked Concrete Based on RBSM and Truss Network Model

Simulation of Chloride Diffusivity for Cracked Concrete Based on RBSM and Truss Network Model

Mesoscale Modelling of the Chloride Diffusion in Cracks and Cracked Concrete

Overview of recent work on self-healing in cementitious materials

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