Desenvolvimento de argamassa expansiva para lavra de rochas ornamentais utilizando minerais não metálicos da região Nordeste do Brasil.

Abstract

Brazil has significant participation in the ornamental rock world market and the Northeast of Brazil is outstanding as a region with fashionable granite and with great acceptation in the outside market, especially in the blocks supply. The use of expansive mortar to ornamental rock dismount is become one of most important method in the extractive industries, due to their advantages when compared with other methods. However, the economic aspects inhibit the increase in the use of expansive mortar in Brazil, due to elevated costs, once is an imported product. The aim of this work is to study some national raw materials, mainly non-metallic minerals from Brazilian northeast region, to obtain expansive mortar. To development of the research it was done characterization analysis (X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), particle size by laser and thermal analysis (DTA and TG)) and technological properties measurement (expansion pressure) for the commercial mortar, to be used as a standard. It was studied some preliminary formulations and from this it was proposed the construction of a laboratory equipment to measure the expansion pressure of the mortars. The results indicate that the formulation show performance and characteristics close to the commercial mortars. The results also indicate the use of calcium carbonate as the main raw material to produce CaO, which is responsible for the expansion pressure and for the dismount of the ornamental rocks by expansive mortar. Finally, it was developed in laboratory and applied “in loco” in a granite block an expansive mortar with 70% of CaO, 20% of CaCO3, 10% of cement and 4% of industrial additive (carboxyl methyl cellulose) with 42% of brackish water and a rupture of the rock occurred with 29 hours after employed.