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L'altération superficielle de dalles de granitoïdes sous climat tropical humide: proposition d'une méthode d'étude expérimentale.

Abstract : Ornamental stones are commonly used in urban areas, particularly in the Abidjan region where their beauty vies with their range. Given this, the concern of the beholder of these ornamental materials is to know how they will behave in the bad weather conditions and other climatic changes observed continuously or almost everyday in tropical rain areas. It is this concern which prompted the present study whose objective is to carry out experiments about the evolution of some kinds of ornamental materials by reproducing tropical-rain-area meteorological phenomena in a laboratory. For this reason, this study consists in designing a model of tropical rain climate and performing experiments in vitro to test the apparatus used to create the relevant weather conditions. To do this, the following variables were taken into account in the study: the speed of raindrop impacts (2,3 m.s-1), calorific energy and its fluctuations expressed in surface temperature ranging from 24° C to 76° C, the hygrometric environment which varies from saturations (rains and nightly dewdrops) and a RH of 85%, as well as wetness (51 metres of water per hour). Prototypes of ornamental stones made of Ivorian ornamental rock deposits from Okrouyo (syenite) and Yakala (rose granite) were used as samples to test the apparatus. At each stage of a 6, 9 and 12-month experiment, the samples were digitalised. Later, using Visilog 5.4 (Noesis, 2001) and Paint Shop Pro 5.0 (Jasc Sofware, 1998), the colour image analysis of the digitalised pictures was started as the most appropriate mode of investigation for comparing the pictures obtained at the different stages of the experiment and those existing at the start. This comparison exercise consisted in removing the initial pictures from those obtained at the different stages of digitalisation. The study of the pictures derived from the removal of the initial ones revealed that there exists a similarity between the areas of ferrallitisation a consequence of the weathering into tropical rain climate, and the area generated through the experimental design proposed herein.
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Submitted on : Monday, February 28, 2005 - 8:00:00 AM
Last modification on : Tuesday, September 29, 2015 - 10:32:44 AM
Long-term archiving on: : Friday, October 19, 2012 - 11:40:09 AM

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Aka Crépin Kouassi. L'altération superficielle de dalles de granitoïdes sous climat tropical humide: proposition d'une méthode d'étude expérimentale.. Sciences of the Universe [physics]. École Nationale Supérieure des Mines de Paris, 2004. English. ⟨pastel-00001081⟩

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