Kapillares Eindringen von Wasser und Salzlösungen in Beton / Penetration of Water and Salt Solutions into Concrete by Capillary Suction

1998 ◽  
Vol 4 (4) ◽  
pp. 399-422 ◽  
Author(s):  
P. Lunk
Keyword(s):  
Spatial Distribution ◽  
Service Life ◽  
Chloride Transport ◽  
Dominant Role ◽  
Time Dependent ◽  
Capillary Absorption ◽  
Salt Solutions ◽  
Back Wall ◽  
Capillary Suction ◽  
Retardation Coefficient

Abstract Capillary suction plays a dominant role in the ingress of chlorides and therefore in the durability of concrete. The capillary absorption of fluids into concrete is analysed in terms of a simple capillary-model. With the help of this model and under given conditions, the water and chloride transport by capillary suction can be described in a realistic way. The fundamental influences of different parameters such as porosity, pore size distribution, moisture content and interaction between fluid and concrete are outlined. The retardation effect as regards capillary chloride transport ('Huckepack-Transport') is characterised by a retardation coefficient. The calculation of time-dependent spatial distribution of water and chloride allows the durability of different concrete grade to be predicted. Here, the service life of the back wall of a rehabilitated avalanche-gallery is calculated under defined requirements.

The Effect of Cracks on Chloride Penetration into Concrete

2007 ◽  
Vol 348-349 ◽  
pp. 769-772 ◽  
Author(s):  
In Seok Yoon ◽  
Erik Schlangen ◽  
Mario R. de Rooij ◽  
Klaas van Breugel
Keyword(s):  
Service Life ◽  
Crack Length ◽  
Significant Influence ◽  
Crack Width ◽  
Chloride Transport ◽  
Crack Depth ◽  
Chloride Penetration ◽  
Critical Crack ◽  
Chloride Migration ◽  
Migration Testing

This study is focused on examining the effect of critical crack width in combination with crack depth on chloride penetration into concrete. Because concrete structures have to meet a minimum service-life, critical crack width has become an important parameter. Specimens with different crack width / crack length have been subjected to rapid chloride migration testing (RCM). The results of this study show a critical crack width of about 0.012 mm. Cracks smaller than this critical crack width are considered not to have a significant influence on the rate of chloride transport inwards, while chloride penetration does proceed faster above this critical crack width.

Spatial Distribution of Local Permeabilities in Fibrous Networks

1992 ◽  
Vol 62 (3) ◽  
pp. 151-161 ◽  
Author(s):  
Susan M. Montgomery ◽  
Bernard Miller ◽  
Ludwig Rebenfeld
Keyword(s):  
Spatial Distribution ◽  
Spatial Heterogeneity ◽  
Heterogeneous Networks ◽  
Flow Direction ◽  
Time Dependent ◽  
Dependent Development ◽  
Fabric Structure ◽  
Elliptical Flow ◽  
Fluid Boundary ◽  
Liquid Flows

The shape of a developing radial fluid boundary in the plane of a fabric is a reflection of the structure of the fabric. Homogeneous fabrics, with permeabilities independent of position, yield circular or elliptical flow fronts, depending on the existence of a universally preferred flow direction. Heterogeneous networks yield flow fronts that deviate from this elliptical shape due to spatial variations in permeability. The time-dependent development of the fluid front that occurs when liquid flows radially in the plane of a fabric may be analyzed using Darcy's law to calculate local fabric permeabilities. The resulting spatial distribution of permeabilities is representative of the spatial heterogeneity of the fabric structure. Sample permeability distributions of geotextile fabrics are discussed.

scholarly journals The Effect of Salt Solutions and Absorption Cycles in the Capillary and Drying Coefficient of Red Brick Samples with Different Joints

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
A. S. Guimarães ◽  
J. M. P. Q. Delgado ◽  
V. P. de Freitas ◽  
A. P. Albuquerque
Keyword(s):  
Molecular Diffusion ◽  
Research Work ◽  
Sodium Sulphate ◽  
Capillary Absorption ◽  
Material Decomposition ◽  
Salt Solutions ◽  
Partial Immersion ◽  
First Order Kinetics ◽  
Building Components ◽  
Best Fit

Rising damp can reduce building’s aesthetical value, comfort, and health mark when combined with the existence of soluble salts in the building components and in the ground water can even lead to material decomposition and compromise its structural performance. This research work intended to study the effect of different absorption cycles of two saturated solutions of sodium sulphate and potassium chloride in the capillary absorption curves obtained through the partial immersion of red brick samples without and with different joints. The results revealed significant differences in the capillary coefficients obtained when samples were tested with salt solutions. In the end of this paper an evaluation of the drying kinetics was presented for all the tested samples. Four different first-order kinetics models, available in the literature, were adjusted to describe the drying process and the results point that the Page and Logarithmic models allow the best fit. The apparent molecular diffusion coefficient for solid red brick samples saturated with different solutions and joints was also estimated.

scholarly journals Sensitivity of Service Life Extension and CO2 Emission due to Repairs by Silane Treatment Applied on Concrete Structures under Time-Dependent Chloride Attack

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Aruz Petcherdchoo
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Treatment Strategies ◽  
Time Dependent ◽  
Life Extension ◽  
Silane Treatment ◽  
Application Time ◽  
Free Service ◽  
Chloride Attack ◽  
Service Life Extension

This paper presents sensitivity of service life extension and CO2 emission due to silane (alkyltriethoxysilane) treatment on concrete structures under time-dependent chloride attack. The service life is predicted by the Crank–Nicolson-based finite difference approach for avoiding the complexity in solving Fick’s second law. The complexity occurs due to time-dependent chloride attack and nonconstant diffusion coefficient of concrete with silane treatment. At the application time of silane treatment, the cumulative CO2 emission is assessed. The effectiveness of silane treatment is defined as the ratio of the service life extension to the cumulative CO2 emission assessed within the corrosion-free service life. The service life extension is defined as the difference between corrosion-free service life of concrete structures without and with time-based application of silane treatment. From the study, the diffusion of chlorides in concrete with silane treatment is found to be retarded. In comparison, the strategy without deterioration of silanes during effective duration is more suitable for service life extension but less effective than that with deterioration. In the sensitivity analysis, there are up to eight parameters to be determined. The service life of concrete structures without silane treatment is most sensitive to the water-to-cement ratio and the threshold depth of concrete structures. Considering only five parameters in silane treatment strategies, the service life is most sensitive to the first application time of silane treatment. The cumulative CO2 emission is most sensitive to either the first application time of silane treatment or the amount of CO2 emission per application.

Expression of ectonucleotidases in the prosencephalon of melatonin-proficient C3H and melatonin-deficient C57Bl mice: spatial distribution and time-dependent changes

2015 ◽  
Vol 362 (1) ◽  
pp. 163-176 ◽  
Author(s):  
Moran Homola ◽  
Martina Pfeffer ◽  
Claudia Fischer ◽  
Herbert Zimmermann ◽  
Simon C. Robson ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Time Dependent ◽  
C57bl Mice

Influence of Frost Damage on Chloride Penetration into Concrete

2016 ◽  
Vol 711 ◽  
pp. 359-366
Author(s):  
Peng Zhang ◽  
Folker H. Wittmann ◽  
Yan Ru Wang ◽  
Tie Jun Zhao ◽  
Guan Ting
Keyword(s):  
Service Life ◽  
Frost Damage ◽  
Chloride Penetration ◽  
Capillary Absorption ◽  
Freeze Thaw ◽  
Durability Design ◽  
Design Service Life ◽  
Before And After ◽  
Deteriorating Process ◽  
Selection Of

In most national and international codes for durability design, service life is estimated after selection of one single and dominant deteriorating process such as carbonation, chloride penetration or frost attack. Application of existing codes has shown, however, that the predicted service life is not reached in practice in most cases. Early damage occurs and as a consequence expensive repair measures become frequently necessary, long before the design service life is reached. One reason for this discrepancy is certainly the fact that in practice each dominant deteriorating process is usually accompanied by other aggravating processes. In this contribution capillary absorption of different types of concrete is studied first. The influence of an increasing number of freeze-thaw cycles on capillary absorption of water is studied first, then chloride penetration before and after exposure to a certain number of freeze-thaw cycles was determined experimentally. It was found that an increasing number of freeze-thaw cycles increases chloride penetration significantly, and hence reduces service life in aggressive environment. It can be concluded that for realistic service life prediction the interaction between frost damage and chloride penetration has to be taken into consideration in regions with low temperatures.

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