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The effect of surface-active compounds on the tensile strength of limestone and porphyry particles |
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The effect of surface-active compounds on the tensile strength of limestone and porphyry particles Authors: M. Brożek, E. Oruba-Brożek
The real strength of solids is affected by the presence of structural defects, i.e. micro-cracks around which the stresses during tension are concentrated. It depends also on the free surface specific energy, which can be reduced by the introduction of surface active compounds (SAC). This paper presents the results of investigations on the influence of surface-active compounds upon the tensile strength of single mineral particles. The tests were performed on limestone and porphyry. The authors determined the distribution of strength of particles without chemical treatment and after treatment with distilled water and solutions of sodium oleate and dodecylamine hydrochloride. The effect of SAC was evaluated according to the average tensile strength value and the wetting angle, determined by the settled drop method. The results indicate that different substances have varied effects in lowering the strength of limestone and porphyry particles. These differences can be explained by the different SAC adsorption rates on the surface of each material which, in consequence, result in different penetration rates in primary micro-cracks (on which the amount of crack-strength lowering depends). It can also be explained by the different number of surface cracks on limestone and porphyry particles. This hypothesis is confirmed by the results of investigations of the wetting angle of both materials by the surface active compounds used in this investigation.
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2011