scholarly journals Experimental Study and Simulation Calculation of the Chloride Resistance of Concrete under Multiple Factors

2021 ◽  
Vol 11 (12) ◽  
pp. 5322
Author(s):  
Yang Ding ◽  
Tong-Lin Yang ◽  
Hui Liu ◽  
Zhen Han ◽  
Shuang-Xi Zhou ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Finite Element Software ◽  
Chloride Resistance ◽  
Simulation Calculation ◽  
Marine Concrete ◽  
Resistance Performance

Cement is widely used in marine concrete, and its resistance to chloride ion corrosion has been widely considered. In this paper, based on a laboratory test, the influence of different hydrostatic pressures, coarse aggregate contents and w/c ratios on the chloride resistance performance is analyzed. Based on COMSOL finite element software, a two-dimensional cementitious materials model is established, and the simulation results are compared with the experimental results. The results show that the penetration depth of chloride ions in cement increases with the increase of the w/c ratio. Under the hydrostatic pressure of 0 MPa, when the w/c ratio is 0.35, the penetration depth of chloride ions is 7.4 mm, and the simulation result is 8.0 mm. When the w/c ratio is 0.45, the penetration depth of chloride ions is 9.3 mm, and the simulation result is 9.9 mm. When the w/c ratio is 0.55, the penetration depth of chloride ions is 12.9 mm, and the simulation result is 12.1 mm. Under different hydrostatic pressures, the penetration depth of chloride ions obviously changes, and with the increase in hydrostatic pressure, the penetration depth of chloride ions deepens. Under the w/c ratio of 0.35, when the hydrostatic pressure is 0.5 MPa, the penetration depth of chloride ions is 11.3 mm, and the simulation result is 12.1 mm. When the hydrostatic pressure is 1.0 MPa, the penetration depth of chloride ions is 16.2 mm, and the simulation result is 17.5 mm.

scholarly journals Layered Double Hydroxides Precursor as Chloride Inhibitor: Synthesis, Characterization, Assessment of Chloride Adsorption Performance

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2537 ◽  
Author(s):  
Lin Chi ◽  
Zheng Wang ◽  
Youfang Zhou ◽  
Shuang Lu ◽  
Yan Yao
Keyword(s):  
Removal Rate ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Ion Removal ◽  
Hydraulic Concrete ◽  
Adsorption Behaviors ◽  
The Stability ◽  
Inhibition Performance ◽  
Double Hydroxides

In this study, the chloride adsorption behaviors of CaAl-Cl LDH precursors with various Ca:Al ratios were investigated. The optimal chloride ion removal rate was 87.06% due to the formation of hydrocalumite. The chloride adsorption products of CaAl-Cl LDH precursors were further characterized by X-ray diffraction analysis and atomic structure analysis, the adsorption mechanism was considered to be co-precipitate process. The chloride adsorption behaviors of cementitious materials blended with CaAl-Cl LDH precursors were further investigated. Leaching test according to Test Code for Hydraulic Concrete (SL352-2006) was performed to testify the stability of chloride ions in the mortar. The results show that more than 98.3% chloride ions were immobilized in cement mortar blended with CaAl-Cl LDH precursor and cannot be easily released again. The inhibition performance of steel in the electrolytes with/without CaAl LDH precursor was investigated by using electrochemical measurements. The results indicate that CaAl LDH precursor can effectively protect the passive film on steel surface by chloride adsorption. Considering the high anion exchange capacities of the LDHs, synthesized chloride adsorbent precursor can be applied as new inhibitors blended in cementitious materials to prevent the chloride-induced deterioration. Moreover, the application of chloride adsorption on CaAl-Cl LDH could also be of interest for the application of seawater blended concrete.

scholarly journals Effect of non-isothermal flow on chloride ion transport in saturated concrete

2021 ◽  
Vol 248 ◽  
pp. 01022
Author(s):  
Chen Peng ◽  
Qing Wu ◽  
Jun Xu
Keyword(s):  
Ion Transport ◽  
Fluid Motion ◽  
Convective Motion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Isothermal Flow ◽  
Ion Concentration ◽  
Effect Of Temperature ◽  
Finite Element Software ◽  
Chloride Ion Transport

The presence of a temperature difference changes the mode of motion of the fluid. The macroscopic motion of the fluid causes the relative displacement between the various parts of the fluid, which in turn affects the transfer of temperature in the medium. To investigate the effect of temperature transfer coupled fluid motion on chloride ion transport in concrete, a mesoscopic model of chloride ion transport in non-isothermal flow of concrete was established and compared with experimental data. Based on the finite element software, the influence of temperature transfer on the internal fluid motion and chloride ion transport of concrete was analyzed. And the effect of convective motion of fluid on the temperature transfer in concrete was studied. It is found that when the heating time is the same, the dynamic viscosity of the fluid in the concrete decreases with the increase of temperature; the chloride ion concentration increases with the increase of temperature at the same depth of concrete; when considering the influence of laminar flow, the temperature is transmitted faster in the concrete and exhibits uneven diffusion from high temperature to low temperature; non-isothermal flow promotes the diffusion of chloride ions in concrete, and the higher the temperature.

Penetration of Chlorine Ion in Concrete under the Coupling Effect of the Continues Pressure Load and the Corrosion Environment

2014 ◽  
Vol 633 ◽  
pp. 140-144
Author(s):  
Wei Hong Li ◽  
Ying Ying Xu
Keyword(s):  
Penetration Depth ◽  
Coupling Effect ◽  
Chloride Ion ◽  
Load Level ◽  
Chloride Ions ◽  
Diffusion Method ◽  
Test Time ◽  
Environment Interaction ◽  
Concrete Durability ◽  
Pressure Load

This paper studies the influence law of experiment time, load level under sustained pressure load and the corrosion environment interaction on the permeability of chloride ion in concrete,which is through natural diffusion method. Experimental results show that with the increase of the test time, the penetration depth of chloride ions in concrete and the content of chloride ions in the same penetration depth is growing. As the load level increases, there is a tendency of the chloride ion content after the first increase and then decrease, the turning point in the middle remains to be studied. The research results have a certain significance for concrete durability design and life prediction in corrosion environment.

Test Research of Chloride Ion Penetration in Concrete Tunnel Lining Structure

2012 ◽  
Vol 446-449 ◽  
pp. 3155-3159
Author(s):  
Zhong Li ◽  
Yan Peng Zhu ◽  
Xiao Yan Cui
Keyword(s):  
Service Life ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Chloride Content ◽  
Chloride Ions ◽  
Tunnel Lining ◽  
Chloride Ion Penetration ◽  
Lining Structure ◽  
Erosion Environment ◽  
Ion Penetration

Chloride ion diffusion coefficient is an important indicator reflected the concrete durability in chloride erosion environment, and affects the service life of concrete structure directly. By the indoor test of chloride acceleration permeability, the chloride ions diffusivity is studied in the tunnel lining structure, and the variation law of the chloride content is tested with the change of penetration depth of different age specimen. Tests shows, with the increases of the penetration depth, the chloride content decrease gradually and finally tend to the initial chloride content of the specimen. Penetration time has a strong cumulative effect on the internal concentration of chloride ions in concrete, the high or low level of chloride ion concentration have a role of promotion or reduction for the chloride ion penetration in the concrete inside. The results provide an important basis for the predictions of service life of tunnel lining in chloride erosion environment.

A Study of Natural Pozzolan Mortars Exposed to Chlorides as a Sustainable Building Material

2015 ◽  
Vol 650 ◽  
pp. 105-113
Author(s):  
Laïd Laoufi ◽  
Mohamed Mouli ◽  
Yassine Senhadji
Keyword(s):  
Blended Cement ◽  
Chloride Ion ◽  
Corrosion Current ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Production Costs ◽  
Supplementary Cementitious Materials ◽  
Reinforcement Corrosion ◽  
Natural Pozzolan ◽  
Mechanical Performances

Reinforcement corrosion is caused either by chloride ions or carbonation, although chloride-induced reinforcement corrosion is the most widespread and serious problem. Moreover, the use of supplementary cementitious materials has been proposed in order to mitigate the durability problem, reduce the production costs and control the emission of greenhouse gases (GHGs). This paper reports the results of a study conducted to investigate the influence of Algerian natural pozzolan on reinforcement corrosion in blended cement mortars exposed to chlorides. Compositions, with replacement levels of 0, 10, 20 and 30% of normal Portland cement by mass of cement by natural pozzolan, were investigated. The exposure solution contained a fixed concentration of 5% sodium chloride. The compressive strength, corrosion potential, corrosion current density, sorptivity, rapid chloride ion penetration, in accordance with the standard ASTM C1202-12, were determined in order to characterize the mechanical and electrochemical behavior of the mortars. It was found that the use of natural pozzolan had resulted in a significant decrease in the corrosion rate of rebars, better mechanical performances and also a resistance to penetration of chlorides ions.

scholarly journals The effect of supplementary cementitious materials on transport properties of cementitious materials - state-of-the-art

2021 ◽  
Vol 22 ◽  
pp. 21-28
Author(s):  
Zaid Ali Abdulhussein ◽  
Katalin Kopecskó
Keyword(s):  
Pore Structure ◽  
Transport Properties ◽  
State Of The Art ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Industrial Applications ◽  
Chloride Ions ◽  
Supplementary Cementitious Materials ◽  
Experimental Investigations ◽  
Cement Binder

The supplementary cementitious materials (SCMs) have recognized many of the beneficial influences on concrete ability to resist the penetration of chloride ions, such as fly ash, slag, silica fume, metakaolin, and other natural pozzolans; this benefit has primarily been ascribed to the refined pore structure that results from the appropriate use of SCMs, which, in turn, results in reduced permeability and ionic diffusivity. The paper illustrates the state-of-the-art research findings on; (1) the classification of the SCMs and physicochemical properties; (2) the influences of SCMs on cement binder and the pore structure under chloride ion permeability; (3) the influences of the SCMs on the carbonation process of the cement binder that aims to determine the optimum relationship between SCMs and concrete transport properties. The interesting experimental investigations of the combined influence of chloride and carbonate permeation in cement binder that implement the latest methods in different curing conditions, types, and level contents of the SCMs will yield new scientific results and proposals for the industrial applications auxiliary materials.

Research on Chloride Ion Diffusion of Concrete Water-Based Capillary Crystalline Waterproofer and its Penetration Depth by Using Electron Microscope

2013 ◽  
Vol 857 ◽  
pp. 27-34 ◽  
Author(s):  
Xin Xiao ◽  
Qi Sen Zhang ◽  
Xiao Ye Liang ◽  
Xiao Ning Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Electron Microscope ◽  
Penetration Depth ◽  
Good Condition ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Ion Diffusion ◽  
Strength Concrete ◽  
Water Based ◽  
Chloride Ion Diffusion

In order to improve the durability of concrete structure, studying reduction effect that water-based capillary crystalline waterproofer has on chloride ion diffusion coefficient in the concrete; analyse the inner microstructure of concrete by using electron microscope, and observe the penetration depth of waterproof agent in concrete directly. Research shows that: the water permeable crystalline waterproof agent can significantly reduce the diffusion coefficient of chloride ions in concrete, after concrete forms, the earlier brush waterproof agent, the longer it cure and its improving effect is more prominent after brushing waterproof agent , reduction rate of chloride ion diffusion coefficient in low strength concrete is higher than high-strength concrete;in good condition of water percolation, by detecting of electron microscope, it proved waterproofing agent can penetrate into internal concrete 6cm at least , the gel produced can be filled with pore and micro crack of concrete, so it can significantly improve the compactness of the whole structure.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

scholarly journals Effect of High-Dispersible Graphene on the Strength and Durability of Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 915
Author(s):  
Xiaoqiang Qi ◽  
Sulei Zhang ◽  
Tengteng Wang ◽  
Siyao Guo ◽  
Rui Ren
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cement Mortar ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ion Penetration ◽  
Cement Mortars ◽  
Strength And Durability ◽  
Durability Performance

Graphene’s outstanding properties make it a potential material for reinforced cementitious composites. However, its shortcomings, such as easy agglomeration and poor dispersion, severely restrict its application in cementitious materials. In this paper, a highly dispersible graphene (TiO2-RGO) with better dispersibility compared with graphene oxide (GO) is obtained through improvement of the graphene preparation method. In this study, both GO and TiO2-RGO can improve the pore size distribution of cement mortars. According to the results of the mercury intrusion porosity (MIP) test, the porosity of cement mortar mixed with GO and TiO2-RGO was reduced by 26% and 40%, respectively, relative to ordinary cement mortar specimens. However, the TiO2-RGO cement mortars showed better pore size distribution and porosity than GO cement mortars. Comparative tests on the strength and durability of ordinary cement mortars, GO cement mortars, and TiO2-RGO cement mortars were conducted, and it was found that with the same amount of TiO2-RGO and GO, the TiO2-RGO cement mortars have nearly twice the strength of GO cement mortars. In addition, it has far higher durability, such as impermeability and chloride ion penetration resistance, than GO cement mortars. These results indicate that TiO2-RGO prepared by titanium dioxide (TiO2) intercalation can better improve the strength and durability performance of cement mortars compared to GO.

Test and Study on Green High-Performance Marine Concrete Containing Ultra-Fine Limestone Powder

2013 ◽  
Vol 368-370 ◽  
pp. 1112-1117
Author(s):  
Jin Hui Li ◽  
Liu Qing Tu ◽  
Ke Xin Liu ◽  
Yun Pang Jiao ◽  
Ming Qing Qin
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Mechanical Performance ◽  
Chloride Ion ◽  
Limestone Powder ◽  
Ion Permeability ◽  
High Quality ◽  
Cracking Resistance ◽  
Slag Powder ◽  
Marine Concrete

In order to solve the environment pollution of limestone powder during production of limestone manufactured sand and gravel and problem of lack of high quality fly ash or slag powder in ocean engineering, ultra-fine limestone powder was selected for preparation of green high-performance marine concrete containing fly ash and limestone powder and that containing slag powder and limestone powder for tests on workability, mechanical performance, thermal performance, shrinkage, and resistance to cracking and chloride ion permeability. And comparison was made between such green high-performance concrete and conventional marine concrete containing fly ash and slag powder. Moreover, the mechanism of green high-performance marine concrete was preliminary studied. Results showed that ultra-fine limestone powder with average particle size around 10μm had significant water reducing function and could improve early strength of concrete. C50 high-performance marine concrete prepared with 30% fly ash and 20% limestone powder or with 30% slag powder and 30% limestone powder required water less than 130kg/m3, and showed excellent workability with 28d compressive strength above 60MPa, 56d dry shrinkage rate below 300με, cracking resistance of grade V, 56d chloride ion diffusion coefficient not exceeding 2.5×10-12m2/s. Mechanical performance and resistance to chloride ion permeability of limestone powder marine concrete were quite equivalent to those of conventional marine concrete. But it had better workability, volume stability and cracking resistance. Moreover, it can serve as a solution to the lack of high quality fly ash and slag powder.

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