PENETRATION OF CHLORIDE IONS INTO HARDENED CEMENT CONSIDERING MULTIPLE IONS IN SEAWATER

2021 ◽  
Vol 77 (3) ◽  
pp. 78-91
Author(s):  
Satoko NAOMACHI ◽  
Yoshitaka KATO
Keyword(s):  
Chloride Ions ◽  
Hardened Cement

Einfluss der elektrochemischen Doppelschicht auf die Sorption und den Transport von Chlorionen im Zementstein / Influence of the electrochemical double layer on sorption and transport of chlorides in hardened cement paste

2000 ◽  
Vol 6 (4) ◽  
pp. 415-428
Author(s):  
O. Wowra ◽  
M.J. Setzer
Keyword(s):  
Double Layer ◽  
Cement Paste ◽  
Building Materials ◽  
Pore Solution ◽  
Chloride Ions ◽  
Transport Processes ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Electrochemical Double Layer

Abstract Besides the formation of Friedel salt the transport and binding of chlorides in concrete is mainly defined by the electrochemical double layer at the interface between cement matrix and pore solution. Due to the alkaline pore solution the surface of hardened cement paste is negatively charged which may change to positive values by the potential regulating calcium ions. Inverting of the surface charge leads to an attraction of anions and therefore, to an adsorption of chloride ions in the diffuse part of the electrochemical double layer. Influence from outside like sulphates and carbon dioxide may lead to a decomposition of Friedel salt. Apart from these effect temperature, pH-value and certain environmental conditions affects the electrochemical double layer as well. The chloride equilibrium is mainly controlled by adsorbed ions in the electrochemical double layer. The model presented here is relevant for the assessment of ion transport processes in mineral building materials. Continuing investigations may lead to optimize transport models and a better evaluation of the critical chloride threshold value in reinforced concrete.

scholarly journals Effect of Chlorides on Conductivity and Dielectric Constant in Hardened Cement Mortar: NDT for Durability Evaluation

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Sunkook Kim ◽  
Joowon Kang ◽  
Sang-Hyo Lee ◽  
Yong Han Ahn
Keyword(s):  
Dielectric Constant ◽  
Pore Formation ◽  
Cement Mortar ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Hardened Cement ◽  
Frequency Range ◽  
Nondestructive Technique ◽  
Normal Frequency

Dielectric constant and conductivity, the so-called EM properties (electromagnetic), are widely adopted for NDT (Nondestructive Technique) in order to detect damage or evaluate performance of concrete without damage to existing RC (reinforced concrete). Among deteriorating agents, chloride ion is considered as one of the most critical threats due to rapid penetration and direct effect on steel corrosion. In the work, cement mortar samples with 3 w/c (water-to-cement) ratios and 4 levels of chloride addition are considered. Conductivity and dielectric constant are measured in the normal frequency range. They increase with strength of mortar and more chloride ions due to denser pore formation. Furthermore, the behaviors of measured EM property are investigated with carbonation velocity and strength, which shows an attempt of application to durability evaluation through EM measurement.

Diffusion of chloride ions in hardened cement pastes

1981 ◽  
Vol 11 (3) ◽  
pp. 395-406 ◽  
Author(s):  
C.L. Page ◽  
N.R. Short ◽  
A. El Tarras
Keyword(s):  
Chloride Ions ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Hardened Cement Pastes

scholarly journals Effects of chloride ions on carbonation rate of hardened cement paste by X-ray CT techniques

2016 ◽  
Vol 122 ◽  
pp. 619-627 ◽  
Author(s):  
Jun-zhe Liu ◽  
Ming-fang Ba ◽  
Yin-gang Du ◽  
Zhi-min He ◽  
Jian-bin Chen
Keyword(s):  
Cement Paste ◽  
Chloride Ions ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
X Ray

Influence of an Anti-Chloride Corrosion Admixture on Density of Cement-Based Materials

2012 ◽  
Vol 430-432 ◽  
pp. 1315-1319
Author(s):  
Wei Zhang ◽  
Xiao Yao ◽  
Ru Mu
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Sem Analysis ◽  
Chloride Ions ◽  
Mineral Admixture ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Chloride Corrosion ◽  
Steel Bar ◽  
Cement Based Materials

A new admixture increasing the density of cement-base composites and hence preventing the penetration of chloride ions is developed and investigated. The new admixture is the combination of traditional mineral admixture and steel bar inhibitor. The composition of the admixture is optimized using water absorption tests. Then the effect of the new admixture on the workability of freshly mixed cement paste as well as the pore structure and SEM analysis of hardened cement paste is experimentally investigated. The results show that the new admixture is effective to increase the density of cement-based materials.

Junction of the Epithelium and Lamina Propria of the Bovine Rumen Mucosa

1967 ◽  
Vol 25 ◽  
pp. 68-69
Author(s):  
Al W. Stinson
Keyword(s):  
Osmium Tetroxide ◽  
Squamous Epithelium ◽  
Short Chain Fatty Acids ◽  
Chloride Ions ◽  
Fermentation Products ◽  
Ruminant Species ◽  
Protective Shield ◽  
Stratified Squamous Epithelium ◽  
Lead Hydroxide ◽  
Acetic Acids

The stratified squamous epithelium which lines the ruminal compartment of the bovine stomach performs at least three important functions. (1) The upper keratinized layer forms a protective shield against the rough, fibrous, constantly moving ingesta. (2) It is an organ of absorption since a number of substances are absorbed directly through the epithelium. These include short chain fatty acids, potassium, sodium and chloride ions, water, and many others. (3) The cells of the deeper layers metabolize butyric acid and to a lesser extent propionic and acetic acids which are the fermentation products of rumen digestion. Because of the functional characteristics, this epithelium is important in the digestive process of ruminant species which convert large quantities of rough, fibrous feed into energy.Tissue used in this study was obtained by biopsy through a rumen fistula from clinically healthy, yearling holstein steers. The animals had been fed a typical diet of hay and grain and the ruminal papillae were fully developed. The tissue was immediately immersed in 1% osmium tetroxide buffered to a pH of 7.4 and fixed for 2 hrs. The tissue blocks were embedded in Vestapol-W, sectioned with a Porter-Blum microtome with glass knives and stained with lead hydroxide. The sections were studied with an RCA EMU 3F electron microscope.

Elucidation of block boundaries as the dissolution channels in hydrated cement

1978 ◽  
Vol 36 (1) ◽  
pp. 484-485
Author(s):  
N.V. Belov ◽  
U.I. Papiashwili ◽  
B.E. Yudovich
Keyword(s):  
Liquid Phase ◽  
Grain Boundaries ◽  
Benzoyl Peroxide ◽  
Phase Contrast ◽  
Active Role ◽  
Point Of View ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Hardened Cement Paste

It has been almost universally adopted that dissolution of solids proceeds with development of uniform, continuous frontiers of reaction.However this point of view is doubtful / 1 /. E.g. we have proved the active role of the block (grain) boundaries in the main phases of cement, these boundaries being the areas of hydrate phases' nucleation / 2 /. It has brought to the supposition that the dissolution frontier of cement particles in water is discrete. It seems also probable that the dissolution proceeds through the channels, which serve both for the liquid phase movement and for the drainage of the incongruant solution products. These channels can be appeared along the block boundaries.In order to demonsrate it, we have offered the method of phase-contrast impregnation of the hardened cement paste with the solution of methyl metacrylahe and benzoyl peroxide. The viscosity of this solution is equal to that of water.

Factors Influencing the Separation of Glu-Plasminogen Affinity Forms I and II by Affinity Chromatography

1984 ◽  
Vol 52 (03) ◽  
pp. 347-349 ◽  
Author(s):  
Daan W Traas ◽  
Bep Hoegee-de Nobel ◽  
Willem Nieuwenhuizen
Keyword(s):  
Affinity Chromatography ◽  
Dissociation Constants ◽  
Ionic Composition ◽  
Chloride Ions ◽  
Factors Influencing ◽  
Two Factors ◽  
Human Plasminogen

SummaryNative human plasminogen, the proenzyme of plasmin (E. C. 3.4.21.7) occurs in blood in two well defined forms, affinity forms I and II. In this paper, the feasibility of separating these forms of human native plasminogen by affinity chromatography, is shown to be dependent on two factors: 1) the ionic composition of the buffer containing the displacing agent: buffers of varying contents of sodium, Tris, phosphate and chloride ions were compared, and 2) the type of adsorbent. Two adsorbents were compared: Sepharose-lysine and Sepharose-bisoxirane-lysine. Only in the phosphate containing buffers, irrespective of the type of adsorbent, the affinity forms can be separated. The influence of the adsorbent can be accounted for by a large difference in dissociation constants of the complex between plasminogen and the immobilized lysine.

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