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.

Influence of the Nanomaterials of Kaolin Content on the Chloride Permeability of Cement Mortar

2017 ◽  
Vol 730 ◽  
pp. 406-411 ◽  
Author(s):  
Xiao Yu Guo ◽  
Ying Fang Fan ◽  
Kun Yang
Keyword(s):  
Compressive Strength ◽  
Diffusion Coefficient ◽  
Cement Mortar ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Permeability

This study investigated the influence of nanokaolin content on the behavior of cement mortar at various curing ages. The fluidity, chloride permeability, bending and compressive strength of cement mortar with various nanokaolin additives were examined. The addition of 0%, 1%, 2%, 3%, 4%, 5% and 6% nanokaolin were taken into consideration. The results showed that the addition of nanokaolin decreases the fluidity of cement mortar, and the fluidity the cement mortar decreases with the increase of nanokaolin additives. It is obtained that the addition of nanokaolin increases both the bending and compressive strength of cement mortar, and with the increase of nanokaolin additives, the bending and compressive strength of cement mortar increase. The addition of 4% nanokaolin can result in a significant low chloride permeability of cement mortar among the seven dosages. The chloride diffusion coefficient of the mortar with the addition of 4% nanokaolin was decreased by 18.93%, 12.68% and 31.05% at 7, 14 and 28 curing days, respectively.

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).

Numerical Stimulation Method of Chloride Concentration in the Concrete Structure Exposed to Chloride Aggressive Environment

2012 ◽  
Vol 193-194 ◽  
pp. 466-471
Author(s):  
Ying Huang ◽  
Jun Wei ◽  
Rong Zhen Dong ◽  
Hui Huang Yan
Keyword(s):  
Thermal Analysis ◽  
Diffusion Coefficient ◽  
Diffusion Equation ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Ion Concentration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Finite Element Software ◽  
Numerical Stimulation

In this paper, based on the similarity between chloride diffusion equation in concrete and heat conduction equation the thermal analysis module of the ANSYS finite element software was used to carry out the numerical simulation for chloride ion diffusion process in concrete. And the numerical results were compared with the analytical solutions of chloride diffusion equation, which showed that the method is effective for the chloride diffusion analysis. Time-dependence of chloride diffusion coefficient in concrete was considered by amending the chloride diffusion coefficient with various parameters. Finally it is a feasible method that the chloride ion concentration in concrete structures was calculated by thermal analysis module of the ANSYS.

Damage and Chloride Penetration of Cement Mortar under Conventional Triaxial Compression

2011 ◽  
Vol 71-78 ◽  
pp. 744-747
Author(s):  
Zu Quan Jin ◽  
Qiu Yi Li ◽  
Chuan Li ◽  
Tie Jun Zhao
Keyword(s):  
Diffusion Coefficient ◽  
Cement Mortar ◽  
Triaxial Compression ◽  
Axial Loading ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Axial Deformation ◽  
Free Chloride ◽  
Conventional Triaxial Compression

In this paper, the influence of conventional triaxial compression on damage and chloride ion penetration of cement mortar are investigated. Conventional triaxial compression experiment was carried out with confining loading of 10Mpa. And the stress-strain curve was measured when axial stress was 50%, 80% and 100% of peak axial loading, and 80% axial loading post-maximum. Then the damaged cement mortars was stored in Qingdao sea water for 30 days, and the free chloride content as well as chloride diffusion coefficient of damaged mortars were quantitatively determined. The experimental results show that the cement mortar is compacted in the end, and shear damaged in the middle under conventional triaxial compression. Compared to cement mortar under uniaxial compression, its compressive strength and axial deformation increases by 1.94 times and 5.6 times when cement mortar under conventional triaxial compression. When the axial stress is less than 48% of peak axial loading, and the axial deformation is less than 0.63mm, the mortar is compacted and its relative dynamic elastic modulus increases with raising axial loading and deformation. The free chloride content in the pressure-bearing side is higher than that in the bottom side. And the free chloride content in the interior of mortar increases with raising axial loading. The chloride diffusion coefficient and axial loading are related in quadratic function. When the axial deformation of mortar is higher than 0.72mm and 1.57mm, the chloride diffusion coefficient of non-load mortar, is less than that of loaded mortar in the pressure-bearing side, and in the bottom side, respectively.

Experimental Study and Numerical Analysis on Chloride Diffusion Coefficient of Concrete with Various Water-Cement Ratios

2017 ◽  
Vol 726 ◽  
pp. 547-552
Author(s):  
Zheng Ren ◽  
Lian Zhen Xiao ◽  
Wen Chong Shi
Keyword(s):  
Diffusion Coefficient ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Ion Diffusion ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
Chloride Ion Diffusion

A rapid chloride ion diffusion coefficient measurement (RCM) was used in this study. The influence of water-cement ratios of 0.30, 0.35 and 0.40 at various ages (3, 7, 14, 28 and 56 days) on chloride ion diffusion coefficient of the concretes and pastes was studied and analyzed. The results show that, with the increase of curing ages, the chloride ion diffusion coefficient of different water-cement ratio of each specimen is decreased. In the early age, the chloride ion diffusion coefficient of the paste with the water-cement ratio of 0.40 is 2~3 times of the paste with water-cement ratio of 0.30 and 0.35, and with the increase of curing age, this difference is gradually decreased. Additionally, the chloride ion diffusion coefficient of the cement paste is 1~2 times of the concrete with same water-cement ratio at different ages. Based on the actual experiment boundary conditions, the process of chloride ions diffusion and permeability was simulated by COMSOL software, and the simulation result was analyzed to predict the permeability of concrete.

Acelerated Test Methods: Determining the Diffusion Coefficient of Concretes in the Saturated Condition

2017 ◽  
Vol 372 ◽  
pp. 91-100
Author(s):  
Tassia Fanton ◽  
João A.M. Bender ◽  
Leandro G. Blois ◽  
Franciele Müller ◽  
André T.C. Guimarães
Keyword(s):  
Diffusion Coefficient ◽  
Standardized Tests ◽  
Chloride Concentration ◽  
Test Methods ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Reinforced Concrete Structure ◽  
Saturated Condition ◽  
Pozzolanic Cement

The chloride diffusion coefficient indicates the capacity of a particular type of concrete to resist chloride penetration and is therefore used to predict the service life of a particular reinforced concrete structure exposed to environments containing this type of aggressive agent. Its experimental determination is time-dependent and time-consuming. For that reason, our study analyzes the characteristic behavior of the diffusion coefficient (D) of concretes in the saturated condition by testing higher NaCl concentrations and lower contamination ages than those used in standardized tests, in addition, the objective is to analyze the behavior of surface chloride concentration (Cs) over time. Therefore, it was concluded that for concrete dosed with pozzolanic cement, the Cs value varied with increasing tendency at higher ages. In addition, the D value obtained by the proposed method presented values ​​close to those obtained by standardized tests at contamination ages of 21 and 35 days.

Influence of Permeability of HCSA Expansive Agent on High Volume Fly Ash Concrete

2011 ◽  
Vol 477 ◽  
pp. 354-358 ◽  
Author(s):  
Fang Fang Hou ◽  
Juan Hong Liu
Keyword(s):  
Diffusion Coefficient ◽  
Fly Ash ◽  
Rapid Determination ◽  
High Volume ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Experimental Conditions ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Expansive Agent

Based on the rapid determination of chloride diffusion coefficient with NEL method and pore structure analysis, the influence of HCSA expansive agent on chloride diffusion coefficient of concrete has been investigated. Besides, the effects of chloride diffusion coefficient of Water-Cement ratio on HCSA expansive concrete have been also analyzed. The results show that on the condition of 55% mixing amount of fly ash, the chloride diffusion coefficient of concrete of no HCSA is 1.96×10－8cm2/s, which is classified moderate. While the concrete mixing HCSA is about 0.62×10－8cm2/s, the permeability belongs to inferior. The effects of permeability of HCSA mixing amount on concrete is not obviously. The Water-Cement ratio affects the concrete permeability. Under the experimental conditions, the water-cement ratio of 0.4 can achieve better effect of the HCSA expansion; Furthermore, the mercury intrusion further verified that incorporating proper amount of HCSA can make the internal structure dense and improve the density and impermeability of concrete.

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