Modelling the loss of strength and porosity increase due to the leaching of cement pastes

Carde, Christophe; François, Raoul

doi:10.1016/s0958-9465(98)00046-8

Cited by 121 publications

(46 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The inclusion of pozzolanic materials in cement-based composites appears to reduce the permeability and fi ll the spaces between the cement grains [10,11] . In particular, pozzolanic materials decrease Ca(OH) 2 content and help to form a tight cement hydrates, which resist leaching but show a small reduction in mechanical properties after the leaching occurs [12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Effect of calcium leaching on the properties of cement-based composites

Lin

Cheng

Huang

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

View full text Add to dashboard Cite

Leaching is one of the major factors that alter the mechanical properties of cementbased composites. This study is aimed to investigate the effect of leaching on the properties of cementbased composites. Specimens with two water/cementitious ratios and two mineral admixtures were tested. An electrical potential was applied to accelerate the leaching process. Compressive strength test, scanning electronic microscopy, thermogravimetric analysis and X-ray diffraction analysis were conducted. Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens, and such effect was prominent on the specimens without mineral admixtures. The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures. The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions. A fair relationship was found between the calcium leaching and the compressive strength.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of calcium leaching on the properties of cement-based composites

Lin

Cheng

Huang

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

View full text Add to dashboard Cite

show abstract

“…The phenomenon consists of the dissolution of calcium and hydroxide ions out of the matrix, which increases its porosity and causes other changes in the material (9)(10).…”

Section: Introductionmentioning

confidence: 99%

A review of sample preparation and its influence on pH determination in concrete samples

Manso

Aguado

2017

Mater. construcc.

View full text Add to dashboard Cite

SUMMARY:If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field. RESUMEN:Revisión sobre la preparación de muestras de hormigón y su influencia sobre la determinación del pH. Determinar el pH de la fase acuosa de los poros de pastas de cemento, morteros y hormigones tiene gran importancia en el monitoreo de los procesos químicos que tienen lugar en los materiales cementiceos. Sin embargo, no existe una normativa que regule el método de preparación de la muestra para la determinación de su pH. Este artículo presenta un estado del conocimiento de diferentes metodologías para la determinación del pH de materiales cementiceos y la influencia del método de preparación según el objetivo. Además, se presenta una campaña experimental comparando tres técnicas diferentes. Dicha campaña contribuye a establecer un criterio simple que ayude al investigador en la selección del método más adecuado dependiendo del objeto de studio. Este artículo tiene por objetivo ser una herramienta sencilla para seleccionar la metodología más fácil y económica para determiner el pH dependiendo del objetivo, especialmente para investigadores noveles o aquellos con escasa experiencia.

show abstract

“…Recently, Saito also reported that the amount of calcium leaching was higher for mortar in contact with chloride solution compared to pure water in his electrical acceleration test (Saito et al 1997). The reason is thought to be due to the increased porosity resulting from the dissolution and the decalcification of the cement hydrates in contact with chloride solution, which is greater than in the case of contact with water (Ono et al 1978;Saito et al 1997;Carde and Francois 1999). Thus chloride penetration through saturated concrete involves calcium leaching in addition to diffusion and binding.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Transport of Chloride and Calcium Ions in Hydrated Cement Systems

Sugiyama

Ritthichauy

Tsuji

2003

ACT

View full text Add to dashboard Cite

This paper presents a new method for numerically calculating the concentration profiles of both solid calcium and total chloride ions (Cl -) in concrete in contact with 3% (0.5 mol/l) sodium chloride (NaCl) solution. Since the diffusion of ions present in the pore solution is a primary controlling factor, the application of mutual diffusion coefficients of corresponding ions that are influenced by the concentration of other coexisting ions is proposed. The method of calculation is based on the generalized form of Fick's First Law suggested by Onsager, which is composed of the Onsager phenomenological coefficient and the thermodynamic force between ions, which occurs according to the gradient of electrochemical potential in a multicomponent concentrated solution for the pore solution. In addition, the chemical equilibrium for Ca(OH) 2 dissolution and C-S-H decalcification are also modeled and coupled with diffusion. Increased porosity due to dissolved Ca 2+ and a chloride binding isotherm are taken into consideration. The concentration profiles of solid calcium and the presence of Friedel's salt in mortar specimens are experimentally identified by the X-ray diffraction method (XRD) and the thermal analysis (TG/DTA) as well as the total chloride profile using an acid extraction method after three years of exposure to 0.5 mol/l NaCl solution. This experimental result verifies the calculation result.

show abstract

Modelling the loss of strength and porosity increase due to the leaching of cement pastes

Cited by 121 publications

References 8 publications

Effect of calcium leaching on the properties of cement-based composites

Effect of calcium leaching on the properties of cement-based composites

A review of sample preparation and its influence on pH determination in concrete samples

Simultaneous Transport of Chloride and Calcium Ions in Hydrated Cement Systems

Contact Info

Product

Resources

About