Methodology of calculating required chloride diffusion coefficient for intended service life as function of concrete cover in reinforced marine structures

2016 ◽  
Vol 73 ◽  
pp. 316-323 ◽  
Author(s):  
H. Justnes ◽  
M.O. Kim ◽  
S. Ng ◽  
X. Qian
Keyword(s):  
Diffusion Coefficient ◽  
Service Life ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Marine Structures

Production of High-Performance Composite Concrete Segment and Experimental Investigation of Materials

2010 ◽  
Vol 168-170 ◽  
pp. 1042-1045
Author(s):  
Ying Li Gao ◽  
Bao Guo Ma
Keyword(s):  
Service Life ◽  
Concrete Structure ◽  
High Performance ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Volume Deformation ◽  
Volume Stability ◽  
High Performance Composite ◽  
Structure Layer

Tunnel lining concrete segment is the most critical and important structural member of shield tunneling. This investigation designed and produced high-performance composite concrete segment (HCCS). Some key indexes that affect the properties of segment were tested, such as impermeability, volume stability, mechanical property, etc. The results indicated that the impermeability of HCCS concrete cover was excellent and the chloride diffusion coefficient decreased one order of magnitude compared to that of the ordinary segment concrete cover, while the service-life of HCCS increased more than ten-fold. The volume stability of HCCS concrete cover and concrete structure layer were good and the better compatibility in the volume deformation of the whole structure was shown. Furthermore, the mechanical properties of concrete cover and concrete structure layer met the project requirement perfectly, ensuring the higher durability and longer service-life of HCCS effectively.

Design and Impermeability of High Durability Reinforced Concrete Segment

2012 ◽  
Vol 174-177 ◽  
pp. 1199-1203
Author(s):  
Xin'gang Wang ◽  
Fang Bin Chen ◽  
Xu Na Ye ◽  
Wei Qin Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Reinforced Concrete ◽  
Water Pressure ◽  
Chloride Ion ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Shield Tunnel ◽  
Main Body ◽  
Chloride Diffusion Coefficient ◽  
High Durability

Reinforced concrete segment is the main body of structure in shield tunnel, and its durability has an important effect on shield tunnel. The durability of High Durability Reinforced Concrete Segment (abbr. HDRC Segment) was investigated by impermeability of single segment and chloride diffusion coefficient of core-drilling. HDRC Segment had high compact cover, concrete cover and high strength structural-layer. Permeable height of HDRC Segment was approximately 0.5 mm when Keeping 4 hours in the constant water pressure of 0.8 MPa, and chloride diffusion coefficient of HDRC Segment was only 4.9×10－13m2/s by NEL method. As for Water impermeability and chloride ion penetration resistance, HDRC Segment is far superior to those of conventional Reinforced Concrete Segment (abbr. conventional RC Segment). It is advantageous to increase durability of HDRC Segment and service life of tunnel engineering.

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 Effects after 1500 Hardening Days on the Microstructure and Durability-Related Parameters of Mortars Produced by the Incorporation of Waste Glass Powder as a Clinker Replacement

2021 ◽  
Vol 13 (7) ◽  
pp. 3979
Author(s):  
Rosa María Tremiño ◽  
Teresa Real-Herraiz ◽  
Viviana Letelier ◽  
Fernando G. Branco ◽  
José Marcos Ortega
Keyword(s):  
Diffusion Coefficient ◽  
Water Absorption ◽  
Glass Powder ◽  
Cementitious Materials ◽  
Cement Industry ◽  
Waste Glass ◽  
Supplementary Cementitious Materials ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Waste Glass Powder

One of the ways of lessening the CO2 emissions of cement industry consists of replacing clinkers with supplementary cementitious materials. The required service life of real construction elements is long, so it is useful to characterize the performance of these materials in the very long term. Here, the influence of incorporating waste glass powder as a supplementary cementitious material, regarding the microstructure and durability of mortars after 1500 hardening days (approximately 4 years), compared with reference mortars without additions, was studied. The percentages of clinker replacement by glass powder were 10% and 20%. The microstructure was studied using impedance spectroscopy and mercury intrusion porosimetry. Differential thermal and X-ray diffraction analyses were performed for assessing the pozzolanic activity of glass powder at the end of the time period studied. Water absorption after immersion, the steady-state diffusion coefficient, and length change were also determined. In view of the results obtained, the microstructure of mortars that incorporated waste glass powder was more refined compared with the reference specimens. The global solid fraction and pores volume were very similar for all of the studied series. The addition of waste glass powder reduced the chloride diffusion coefficient of the mortars, without worsening their behaviour regarding water absorption after immersion.

scholarly journals Influence of Hydrostatic Pressure and Cationic Type on the Diffusion Behavior of Chloride in Concrete

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2851
Author(s):  
Huanqiang Liu ◽  
Linhua Jiang
Keyword(s):  
Diffusion Coefficient ◽  
Hydrostatic Pressure ◽  
Diffusion Model ◽  
Coupling Effect ◽  
Experimental Results ◽  
Chloride Diffusion ◽  
Concrete Durability ◽  
Chloride Diffusion Coefficient ◽  
Diffusion Behavior ◽  
Diffusion Source

The durability of the concrete in underground and marine engineering is affected by the underground and ocean environment. Chloride diffusion coefficient under hydrostatic pressure is a key parameter of concrete durability design under corresponding conditions. Therefore, this paper studies the diffusion behavior of chloride in different diffusion source solutions by experiment and simulation. Based on the experimental results, this paper proposes a new chloride diffusion model under the coupling effect of diffusion and convection. The interaction of ions and compounds in the diffusion source solutions, concrete pore fluid, and concrete material are considered in the new chloride diffusion model. The experimental results show that chloride diffusion rate is significantly affected by hydrostatic pressure, which increases with the increase of hydrostatic pressure. The chloride diffusion coefficient shows a certain difference in difference diffusion source solutions. The chloride diffusion coefficient in divalent cationic diffusion source solutions is the largest, the chloride diffusion coefficient in the divalent and monovalent cationic compound ones is in the middle, and the chloride diffusion coefficient in the monovalent cationic ones is the smallest. There is a linear relationship between the chloride diffusion coefficient and the hydrostatic pressure whether in single or combined cationic diffusion source solutions.

scholarly journals MODELLING CHLORIDE DIFFUSION IN CONCRETE WITH INFLUENCE OF CONCRETE STRESS STATE

2017 ◽  
Vol 23 (7) ◽  
pp. 955-965 ◽  
Author(s):  
Jian WANG ◽  
Pui-Lam NG ◽  
Weishan WANG ◽  
Jinsheng DU ◽  
Jianyong SONG
Keyword(s):  
Experimental Data ◽  
Diffusion Coefficient ◽  
Stress State ◽  
Diffusion Model ◽  
Stress Ratio ◽  
Chloride Diffusion ◽  
Influence Coefficient ◽  
Chloride Diffusion Coefficient ◽  
Stress Influence ◽  
Concrete Stress

Under coastal or marine conditions, chloride erosion is the major accelerating factor of reinforcement corrosion. Therefore, it is of vital importance to investigate the chloride diffusion model. Research reveals that the concrete stress state has great influence on chloride diffusion; therefore a stress influence coefficient was incorporated in chloride diffusion coefficient model by many researchers. By referring to the experimental data from eight different researchers, the law between stress influence coefficient and concrete stress ratio is studied in detail, and equations relating the stress influence coefficient with the concrete stress ratio are established. Compared with three typical existing groups of equations, it is found that the proposed equations give the most accurate estim.ation of the stress influence coefficient. Hence, the proposed equations can be adopted to improve the valuation of chloride diffusion coefficient, and a modified chloride diffusion model is put forward. Three groups of experimental data are used to validate the modified chloride diffusion model, which is shown to be reasonable and having high prediction accuracy.

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