Resistencia química del hormigón. XXIII. Influencia de la adición de escoria a un cemento portland resistente al yeso. Estudio de la concentración iónica del sistema cemento 2/escoria-agua potable filtrada

Abstract

In this study, which follows on from others, the pH variation is examined and also that of the concentration of Ca (II) and SO₄ (II) ions in the mediums (filtered potable water) in which the test samples of mortar (1: 3) made with industrial portland cement resistent to gypsum (cement 2 < > P-450-Y) and with the mixtures cement 2/slag = 85/15 - 65/35 - 40/60 and 30/70, in weight, have been submerged throughout the curing period (21 days) and, subsequently, for 56 - 90- 180 and 360 days (preservation periods), at this stage. In the same way, the chemical composition of these solid stages was determined by XRD (calcite, in both periods and, also, aragonite during the preservation period of the series of test samples made only with cement 2); an account of this was given in (2). In this cement 2/slag-filtered potable water system, it has been shown that an increase in the content of Ca (II) occurs in dissolution and the solid stages mentioned, and also in the pH value, depending on the mixture used to make up the different series of test samples and the length of preservation time. The quantities of Ca (II) found in the different dissolutions (filtered potable water) are normally smaller than 0.1 x 10^-2 moles, while in the new solid stages they are greater than this quantity and, as a general rule, exceed 0.5 X 10^-2moles. The SO₄ (II) ion has not been detected in the new solid stages, but has been found in small quantities in the different liquid stages (filtered potable water). The content of these ions is normally of the same order as that of filtered potable water in those mediums in which the different series of test samples have been submerged, with the exception of those mediums which have had the test samples with greatest slag content (60 and 70%, in weight) submerged in them.