Os sais solúveis nos materiais de construção da cidade de Campina Grande, Paraíba.

Abstract

The work here presented it is part of a group of researches regarding quality of the materials used by the professionals of the civil construction of our area. That group of researches, that he/she stops in the phenomenon efflorescences, he/she has as study object the present soluble salts in these materials. Those salts produce the calls efflorescences and subcfflorescences, whose occurrences bring I get great damages to the structures of the civil works. The soluble salts, that they create the efflorescences and subcfflorescences, they can be originating from of the raw materials, of the construction materials and its components, of the existent water in the underground and/or of the own soil in which the work is located. The efflorescences and subefflorescences result of the crystallization of the soluble salts, in the surfaces and/or in the internal pores of the materials and in the construction pieces, in the form of saline deposits, these resultants of the migrations and posterior evaporation of saline solutions aqueous. The efflorescences brings in itself a more problem of aesthetic order than of structural order, unlike the subefflorescences, that due to the internal tensions produced by those, they cause more harmful structural effects. In our study, we studied samples of coarse aggregate, it sands and sand-clay mixtures, marketed in the city of Campina Grande, in the state of Parafba, with the objective of studying its potential efflorescences; the samples of material were collected at sixteen commercial stores of materials of construction of the referred city. The samples performed a total of forty eight, subdivide in sixteen samples of coarse aggregate, sixteen samples of sand and sixteen sand-clay mixtures, properly beneficiaries, stored and classified. They were used, in the development of that research, the Methodologies 2.34 to 2.40, of EMBRAPA (1979), with the objective of quantification of the ionic composition of the extracts of saturation of the forty eight studied samples. Besides the methodologies, above mentioned, the one of determination of the solid residues were used and of the electric conductivity (EMBRAPA), and of the sulphates determination (APHA) of the respective samples. The determination of the electric conductivity (CE) and of the total solid residues serve to the elaboration of an equation that correlated electric conductivity and percentage of total soluble salts (% Total Soluble Salts). Through statistical studies, of simple lineal regression, based on the work accomplished by Figueircdo and adaptation of the equation developed by Richards, such correlation was gotten. In the development of the work, two loamy materials were used for die making of the "efflorwicks", that they tested the efflorescences degree in ambient conditions of the analyzed samples, based on the study developed by Nascimento (1998) and recommendations of Amberg & Washburn (1946). Based on the Brazilian norms NB-1/78, of ABNT and Spanish HEY - 80, indicated by Canovas (1988), it can be developed the analysis and discussion of the results. The obtained results indicate to be possible the determination of the total percentage of soluble salts through the electric conductivity and that the studied samples of coarse aggregate, it sands and sand-clay mixtures do not present harmful text of salinity. Of the accomplished study, it cannot him still to end that, the possible efflorescences and subefflorescences are not originating from of the samples coarse aggregate, of sand or of sand-clay mixtures used in the civil works, and that through a good drainage and of a good drainage the problem can be avoided, because, the largest influence factor is the presence of water.