PHYSICAL-MECHANICAL CHARACTERIZATION OF BRAZILIAN NATURAL STONES: APPARENT DENSITY, POROSITY, WATER ABSORPTION, AND CAPILLARITY DETERMINATIONS

Caracterização físico-mecânica de rochas ornamentais do Brasil: determinação de densidade aparente, porosidade, absorção hídrica e capilaridade

Abstract

Natural Stones rocks are natural materials of high nobility and high chemical and physical resistance, properties that provide them with great durability. When exposed to weather conditions over time, they suffer some type of degradation, with the main agent being the percolation of fluids, which due to their compositions can interfere with the intrinsic factors of the rocks, either in environmental conditions or in different applications. In this sense, technological characterization emerges as a predictive diagnostic tool and assertive indication regarding performance, durability, and the need for some protective action for stone materials. Using petrographic analysis and tests that determine characteristics such as porosity and absorption, it is possible to identify patterns and define parameters, for example, of the permeability of the materials and on the need or not for the application, in particular, of protectors such as the recent oil-water repellents. To evaluate the effectiveness of applying these protectors, seventeen Brazilian ornamental rocks were previously tested, based on the NBR 12766 standards for determining the physical indexes and the EN 1925 for determining the water absorption coefficient by capillarity. The results showed four permeability patterns based on the saturation time and slope of the absorption curve and the relation between total absorption is not fully direct with the capillarity values. Based on this information, indications about protective treatments can be considered.