scholarly journals Chloride Resistance of Portland Cement-Based Mortar Incorporating High Aluminate Cement and Calcium Carbonate

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 359 ◽  
Author(s):  
Yunsu Lee ◽  
Seungmin Lim ◽  
Hanseung Lee
Keyword(s):  
Diffusion Coefficient ◽  
Calcium Carbonate ◽  
Pore Volume ◽  
Binding Capacity ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Binding ◽  
Chloride Resistance ◽  
Aluminate Cement ◽  
Capillary Pore

Whether chloride resistance is highly influenced by chloride binding capacity remains unknown. In this study, the chloride resistance of Portland cement-based mortar incorporating aluminate cement and calcium carbonate was investigated considering the chloride binding capacity, pore structures and chloride diffusion coefficient from non-steady state chloride migration and natural chloride diffusion. The cement hydrates were investigated using X-ray diffraction and thermogravimetric analysis. The chloride binding capacity was evaluated based on the chloride adsorption from the solutions using the adsorption isotherm. The aluminate cement, as an available alumina source, can stimulate the formulation of layered double hydroxides, which in turn can increase the chloride binding capacity. The results of mercury intrusion porosimetry show that non-substituted (control) and substituted (only aluminate cement) specimens have capillary pore volume 8.9 vol % and 8.2 vol %, respectively. However, the specimen substituted with aluminate cement and calcium carbonate shows a higher capillary volume (12.9 vol %), which correlates with the chloride diffusion coefficient. Although the specimen substituted with calcium carbonate has a higher chloride binding capacity than the control, it does not necessarily affect the decrease in the chloride diffusion coefficient. The capillary pore volume can affect not only the chloride diffusion but also the chloride adsorption.

scholarly journals Effect of Fly Ash as Cement Replacement on Chloride Diffusion, Chloride Binding Capacity, and Micro-Properties of Concrete in a Water Soaking Environment

2020 ◽  
Vol 10 (18) ◽  
pp. 6271 ◽  
Author(s):  
Jun Liu ◽  
Jiaying Liu ◽  
Zhenyu Huang ◽  
Jihua Zhu ◽  
Wei Liu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Fly Ash ◽  
Binding Capacity ◽  
Chloride Ion ◽  
Chloride Content ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Binding ◽  
Test Results ◽  
New Equation

This paper experimentally studies the effects of fly ash on the diffusion, bonding, and micro-properties of chloride penetration in concrete in a water soaking environment based on the natural diffusion law. Different fly ash replacement ratio of cement in normal concrete was investigated. The effect of fly ash on chloride transportation, diffusion, coefficient, free chloride content, and binding chloride content were quantified, and the concrete porosity and microstructure were also reported through mercury intrusion perimetry and scanning electron microscopy, respectively. It was concluded from the test results that fly ash particles and hydration products (filling and pozzolanic effects) led to the densification of microstructures in concrete. The addition of fly ash greatly reduced the deposition of chloride ions. The chloride ion diffusion coefficient considerably decreased with increasing fly ash replacement, and fly ash benefits the binding of chloride in concrete. Additionally, a new equation is proposed to predict chloride binding capacity based on the test results.

Influence of Stone Dust in Manufactured Sand on Resisting Chloride Penetration in Marine Concretes

2012 ◽  
Vol 174-177 ◽  
pp. 1419-1423
Author(s):  
Jian Bo Xiong ◽  
Peng Ping Li ◽  
Sheng Nian Wang
Keyword(s):  
Diffusion Coefficient ◽  
Pore Structure ◽  
Binding Capacity ◽  
Chloride Penetration ◽  
Dust Content ◽  
Chloride Diffusion ◽  
Fine Aggregate ◽  
Chloride Diffusion Coefficient ◽  
Manufactured Sand ◽  
Stone Dust

In China, manufactured sand has been widely used as fine aggregate in concrete. Therefore, it is necessary to investigate the effect of manufactured sand on durability of concrete. This research studies the influence of stone dust content in manufactured sand on resisting chloride penetration in marine concrete by strength and other physical mechanical tests, XRD, TGA and pore structure analysis. Test results have shown that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand when the stone dust content increasing from 3% to 13%. The stone dust in fine aggregate was participated in hydration procedure of cementitious, which will promote the hydration degree of cementitious and increase the chloride binding capacity of hydration product. The influence of stone dust in fine aggregate on chloride diffusion coefficient were the combined effects of concrete pore structure and cementitious hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient.

scholarly journals EFFECTS OF BLAST FURNACE SLAG ON CHLORIDE PERMEABILITY OF CONCRETE

2012 ◽  
Vol 15 (2) ◽  
pp. 70-80
Author(s):  
Mien Van Tran ◽  
Yen Thi Hai Nguyen ◽  
Thi Nguyen Cao
Keyword(s):  
Diffusion Coefficient ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Binding Capacity ◽  
Concrete Strength ◽  
Steel Reinforcement ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Permeability ◽  
Furnace Slag

Chloride-induced corrosion of steel reinforcement is the main cause of deterioration of reinforced concrete structures in marine environments. The penetration of chlodride ions into concrete cover that accelerates corrosion process of steel reinforcement, this affects the bearing capacity of structures. This paper investigates on chloride permeability cheracteristic of concrete using blast furnace slag in terms of chloride diffusion coefficient and chloride binding capacity. The concrete used in this research has grade of 45MPa and the slag content replacement of cement PC50 is in range of 0% - 70%. The chloride diffusion coefficient of concrete is determined by ASTM C1202 and NordTest NT Build 492. Results showed that the blast furnace slag replacement increases (from 0% to 50%), the chloride ion diffusion coeffient decreases and bound chloride content in concrete increases. It is clear to conclude that blast furnace slag can be used to replace cement PC50 in range of 30% to 40% in order to increase the resistance of concrete to chloride penetration without affecting concrete strength.

Research on Chloride Diffusion Model in Pre-Stressed Concrete with Sulfate Attack

2012 ◽  
Vol 166-169 ◽  
pp. 1935-1940
Author(s):  
Rong Gui Liu ◽  
Jing Li ◽  
Huan Li
Keyword(s):  
Diffusion Coefficient ◽  
Binding Capacity ◽  
Chloride Ion ◽  
Sulfate Attack ◽  
Ion Concentration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Influence Of Water ◽  
Binder Ratio ◽  
Chloride Environment

Chloride diffusion coefficient is significant to the durability of pre-stressed concrete in chloride environment. The factors which influence chloride diffusion coefficient in pre-stressed concrete structures eroded by chloride ion is of great importance, including porosity, chloride ion binding capacity and the stress of pre-stressed concrete etc. Based on the Fick’s second law and existing models, the model of chloride ion diffusion in pre-stressed concrete with sulfate attack is established. It is analyzed that the influence of water-binder ratio and sulfate ion concentration and erosion time on concentration distribution of chloride ion in concrete. Compared to test data and project examples, it is confirmed that the model is useful.

scholarly journals Modeling Chloride Diffusion Coefficient of Steel Fiber Reinforced Concrete under Bending Load

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Qiannan Wang ◽  
Wei Sun ◽  
Liping Guo ◽  
Chunping Gu ◽  
Jinyu Zong
Keyword(s):  
Diffusion Coefficient ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Steel Fiber Reinforced Concrete ◽  
Chloride Resistance ◽  
Bending Load

The chloride diffusion coefficient is the most important parameter when predicting chloride ingress in concrete. This paper proposed a model for calculating the chloride diffusion coefficient of steel fiber reinforced concrete (SFRC). Considering the concrete structures in service are usually subjected to external loads, the effect of bending load was discussed and expressed with a stress factor ks in the model. The chloride diffusion coefficient of cement paste was calculated with capillary porosity and then used to predict the chloride diffusion coefficient of SFRC. Some factors in the model were determined with experimental results. Chloride bulk diffusion tests were performed on SFRC and plain concrete (without fiber) specimens under bending load. SFRC showed slightly better chloride resistance for unstressed specimens. The compressive stress decreased the chloride diffusion coefficient of SFRC, while it caused no change in plain concrete. For the tensile zone, the chloride resistance of concrete was improved significantly by adding steel fibers. Overall, SFRC performed better chloride resistance, especially under bending load. The proposed model provides a simple approach for calculating the chloride diffusion coefficient of SFRC under bending load.

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.

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