Ion binding isotherms of building materials
| Main Authors: | Milena Pavlíková, Robert Černý, Lukáš Fiala |
|---|---|
| Format: | info Proceeding |
| Terbitan: |
, 2008
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| Online Access: |
https://zenodo.org/record/3561842 |
Daftar Isi:
- Determination of chloride binding isotherms is mostly confined to the concrete research because combination of chloride penetration and concrete carbonation accelerates the process of steel corrosion. However, the presence of chlorides can present a potential danger also for many other materials. For instance, very frequent source of chlorides in building materials are salts used for winter maintenance of pavements and footways. They can diffuse either into underground soil or directly into the masonry so that they can damage renders, insulation materials and the masonry itself. The corrosion effects of these salts are mostly related to their crystallization from the solution, recrystallization from the solid phase, sometimes also to chemical reactions with building materials themselves. Chloride binding isotherms are mostly determined by the method of Tang and Nilsson based on the adsorption from solution. The measuring procedure is developed originally for crushed samples of cement paste and it is assumed that the content of cement is the main criterion for a possible recalculation to real concrete or cement mortar. However, the chloride binding capacity can be affected by many other factors, such as the change in the porous structure and pore distribution due to the application of different aggregates, the presence of various admixtures etc. In this paper, the chloride binding isotherms are determined for several different types of building materials, among them cement paste, ceramic brick, mineral wool, and calcium silicate. Several different techniques are used for the concentration measurement, and the comparison of applied methods is done. The measurements involve common analytical determination of chloride concentration, application of ion selective electrodes and of the TDR method. The experiments are performed basically on small but not crushed specimens so that the effect of the porous structure is respected. However, also the experiment with crushed samples as in the original procedure by Tang and Nilsson is done for the sake of comparison and the differences analyzed.
- Presenters: name: Milena Pavlíková affiliation: (Czech Technical University in Prague, Faculty of Civil Engineering, Department of Materials Engineering and Chemistry) email: milena.pavlikova@fsv.cvut.cz name: Lukáš Fiala affiliation: (Czech Technical University in Prague, Faculty of Civil Engineering, Department of Materials Engineering and Chemistry) email: fialal@fsv.cvut.cz