Application of Two Different Methods for Determination of Water and Chloride Transport Parameters of Building Stones

2014 ◽  
Vol 595 ◽  
pp. 143-148
Author(s):  
Zbyšek Pavlík ◽  
Jan Fořt ◽  
Milena Pavlíková ◽  
Robert Černý
Keyword(s):  
Chloride Transport ◽  
Water Solution ◽  
Chloride Concentration ◽  
Moisture Diffusivity ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Transport Parameters ◽  
Chloride Absorption

The transport of 1M NaCl water solution in three different types of sandstones is studied For basic characterization of studied materials, their chemical composition, porosity, bulk density and matrix density are accessed. The chloride transport is analyzed using two different methods. In the first one, the chloride absorption coefficient is measured on the basis of a modified sorptivity concept. The second method consists in carrying out an inverse analysis of experimentally measured moisture and chloride concentration profiles, leading to the determination of chloride diffusion coefficient as a function of chloride concentration, and moisture diffusivity as a function of moisture content. The chloride transport properties obtained for the particular studied materials are compared and the observed differences are discussed.

scholarly journals Numerical Simulation of Non-Uniformly Distributed Corrosion in Reinforced Concrete Cross-Section

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3975
Author(s):  
Magdalena German ◽  
Jerzy Pamin
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Corrosion Current ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Initiation Phase ◽  
Chloride Corrosion ◽  
Cover Thickness

Reinforced concrete structures can be strongly damaged by chloride corrosion of reinforcement. Rust accumulated around rebars involves a volumetric expansion, causing cracking of the surrounding concrete. To simulate the corrosion progress, the initiation phase of the corrosion process is first examined, taking into account the phenomena of oxygen and chloride transport as well as the corrosion current flow. This makes it possible to estimate the mass of produced rust, whereby a corrosion level is defined. A combination of three numerical methods is used to solve the coupled problem. The example object of the research is a beam cross-section with four reinforcement bars. The proposed methodology allows one to predict evolving chloride concentration and time to reinforcement depassivation, depending on the reinforcement position and on the location of a point on the bar surface. Moreover, the dependence of the corrosion initiation time on the chloride diffusion coefficient, chloride threshold, and reinforcement cover thickness is examined.

scholarly journals Chloride Transport in Undersea Concrete Tunnel

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yuanzhu Zhang ◽  
Xiaozhen Li ◽  
Guohua Yu
Keyword(s):  
Water Saturation ◽  
Chloride Transport ◽  
Water Pressure ◽  
Chloride Concentration ◽  
Solution Concentration ◽  
Chloride Diffusion ◽  
Hydraulic Pressure ◽  
Chloride Diffusion Coefficient ◽  
External Water Pressure ◽  
External Water

Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.

New Type of Lime Plaster with Pozzolana Admixture for Renewal of Historical Buildings

2011 ◽  
Vol 324 ◽  
pp. 336-339 ◽  
Author(s):  
Zbyšek Pavlík ◽  
Milena Pavlíková ◽  
Jiří Maděra ◽  
Robert Černý
Keyword(s):  
Computer Code ◽  
Moisture Diffusivity ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Simulation Tool ◽  
Historical Buildings ◽  
Matrix Density ◽  
New Type ◽  
Lime Plaster

Lime plaster modified with pozzolana based on calcined kaoline mixed with mudstone and reference lime plaster are studied in the paper. For the studied materials, determination of bulk density, matrix density and total open porosity is done first. Then, specific attention is paid to the assessment of moisture diffusivity and chloride diffusion coefficient that are considered as decisive parameters for the materials’ durability. The measured data are used as input parameters for computational modeling of studied materials’ performance using computer code TRANSMAT 6.2 based on finite element computer simulation tool. On the basis of measured and calculated results, the applicability of newly developed plaster for renewal of historical buildings is discussed.

scholarly journals Experimental Study on Effective Chloride Diffusion Coefficient of Cement Mortar by Different Electrical Accelerated Measurements

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 240
Author(s):  
Jianlan Chen ◽  
Jiandong Wang ◽  
Rui He ◽  
Huaizhu Shu ◽  
Chuanqing Fu
Keyword(s):  
Diffusion Coefficient ◽  
Cement Mortar ◽  
Early Stage ◽  
Chloride Concentration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Good Consistency ◽  
Determination Methods

This study investigated the effective chloride diffusion coefficient of cement mortar with different water-to-cement ratio (w/c) under electrical accelerated migration measurement. The cumulative chloride concentration in anode cell solution and the cumulative chloride concentration drop in the cathode cell solution was measured by RCT measurement and the results were further used to calculate the chloride diffusion coefficient by Nordtest Build 355 method and Truc method. The influence of w/c on cement mortar’s chloride coefficient was investigated and the chloride diffusion coefficient under different determination methods were compared with other researchers’ work, a good consistency between this work’s results and literatures’ results was obtained. The results indicated that the increased w/c of cement mortar samples will have a higher chloride diffusion coefficient. The cumulative chloride concentration drop in the cathode cell solution will have deviation in early stage measurement (before 60 h) which will result in overestimation of the effective chloride diffusion coefficient.

scholarly journals Influence of Pore Structure on Chloride Penetration in Cement Pastes Subject to Wetting-Drying Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Honglei Chang ◽  
Zhiwu Zuo ◽  
Mingyue Qu ◽  
Fei Wang ◽  
Zhi Ge ◽  
...  
Keyword(s):  
Pore Structure ◽  
Penetration Rate ◽  
Error Function ◽  
Chloride Concentration ◽  
Total Porosity ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Pastes ◽  
The Matrix

Copious studies have discovered a phenomenon that a chloride concentration peak appears on the surface of concrete under cyclic drying-wetting environments. In such cases, the chloride diffusion coefficient (D) obtained through directly fitting the standard error function of Fick’s second law is no longer accurate. The more reliable D obtained by the method proposed by Andrade is employed in this research to investigate the influence of pore structure on chloride penetration rate of pastes. The results show that both the effective coefficient (Deff) and the apparent coefficient (Dapp) increase with total porosity, the most probable pore size, and water absorption porosity, suggesting that the increase of the three pore structure parameters accelerates chloride penetration rate under cyclic wetting-drying condition. The increase of the three parameters makes more room available and eases the difficulty for salt solution to enter the matrix and thus leads to the augmentation of chloride transporting in matrix.

Influence of PCM Admixture on Thermal Behavior of Composite Plaster

2014 ◽  
Vol 1054 ◽  
pp. 209-214 ◽  
Author(s):  
Jan Fořt ◽  
Anton Trník ◽  
Zbyšek Pavlík
Keyword(s):  
Thermal Properties ◽  
Heat Storage ◽  
Indoor Climate ◽  
Transport Parameters ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Latent Heat Storage ◽  
Change Material

Experimental investigation of the effect of phase change material (PCM) admixture on thermal properties of composite plaster is researched in the paper. Due to its latent heat storage, the applied PCM represents promising way for reduction of buildings energy consumption spent for heating and air conditioning. The investigated composite material is based on commercial dry plaster mixture modified by microencapsulated PCM admixture Micronal DS 5038 produced BASF. The particle size distribution of PCM admixture, original dry plaster mixture, and particular dry mixture with PCM addition are measured on laser diffraction principle. For characterization of the developed materials, measurement of their basic physical properties is done. Specific attention is paid to thermal properties of research materials, whereas the heat transport parameters are measured using transient impulse device, and the DSC (difference scanning calorimetry) analysis is applied for determination of temperatures of phase transitions, enthalpy of fusion and crystallization, and temperature dependent specific heat capacity. The obtained results show significant improvement of the heat storage capacity of PCM modified plasters in dependence on temperature, what can be beneficially used for regulation of the indoor climate.

scholarly journals Experimental Study on Chloride Ion Diffusion in Concrete under Uniaxial and Biaxial Sustained Stress

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5717
Author(s):  
Xiaokang Cheng ◽  
Jianxin Peng ◽  
C.S. Cai ◽  
Jianren Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Compressive Stress ◽  
Stress Level ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Ion Diffusion ◽  
Chloride Ion Diffusion

The existence of axial and lateral compressive stress affect the diffusion of chloride ions in concrete will lead to the performance degradation of concrete structure. This paper experimentally studied the chloride diffusivity properties of uniaxial and biaxial sustained compressive stress under one-dimensional chloride solution erosion. The influence of different sustained compressive stress states on chloride ion diffusivity is evaluated by testing chloride concentration in concrete. The experiment results show that the existence of sustained compressive stress does not always inhibit the diffusion of chloride ions in concrete, and the numerical value of sustained compressive stress level can affect the diffusion law of chloride ions in concrete. It is found that the chloride concentration decreases most when the lateral compressive stress level is close to 0.15 times the compressive strength of concrete. In addition, the sustained compressive stress has a significant effect on chloride ion diffusion of concrete with high water/cement ratio. Then, the chloride diffusion coefficient model under uniaxial and biaxial sustained compressive stress is established based on the apparent chloride diffusion coefficient. Finally, the results demonstrate that the chloride diffusion coefficient model is reasonable and feasible by comparing the experimental data in the opening literature with the calculated values from the developed model.

scholarly journals Experimental Investigation on Chloride Diffusion Coefficient of Self-compacting Concrete in the Oman Sea

2020 ◽  
Author(s):  
Naser Nosratzehi ◽  
Mahmoud Miri
Keyword(s):  
Diffusion Coefficient ◽  
Environmental Conditions ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Atmospheric Conditions ◽  
Self Compacting Concrete ◽  
Normal Concrete ◽  
Oman Sea

Chloride ion penetration is an important parameter influencing the service life of a concrete structure, especially in aggressive environments. Severe chloride-induced corrosion of reinforced concretes has been reported in the southern part of Iran in the region of Oman Sea. In this paper, the effect of different environmental conditions of the Oman Sea on chloride penetration and mechanical properties of self-compacting concrete (SCC) and normal concrete (NC) is investigated. For this purpose, a number of prismatic specimens were exposed to various environmental conditions such as tide, submersion and atmospheric conditions. Surface chloride concentration and diffusion coefficient of SCC in these zones were calculated based on Fick’s second law, at 28, 90 and 150 days and compared with NC. Based on the values obtained in this study, relationships are proposed for concrete permeability and surface chloride of self-compacting concrete (SCC) at different ages in different aggressive environments. By determining the corrosion time based on these relations, it is observed that for a given water-to-cement ratio, the self-compacting concrete (SCC) has higher durability compared to normal concrete (NC).

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