Resistencia química del hormigón XXII. Influencia de la adición de escoria a un cemento portland de alta resistencia inicial. Estudio de la concentración iónica del sistema: cemento 1/escoria-agua de mar artificial
Authors: Gaspar-Tebar Demetrio , Sagrera-Moreno José Luis 
Published: July 2012

In this present work, a continuation of others, there is studied the variation of pH, as likewise the concentration of the ions Ca (II), Mg (II), SO4 (II) and Cl (I) of artificial sea water (ASTM D 1141-75) in which there have been submerged the series of test specimens of mortar (1: 3) made with an industrial Portland cement of high initial resistance (cement 1 < > P-550-ARI) and with the mixtures cement 1/slag = 85/15 - 65/35 - 40/60 and 30/70, in weight, during 56-90- 180 and 360 days (periods of conservation-attack), in this stage, after the curing period (1 day in damp chamber and 21 days under filtered drinking water). There is likewise studied the content of the ions Ca (II), Mg (II) and SO4(II) of the new solid phases formed in said means of conservation-attack. The structural composition of said solid phases and of the enriched fraction of the test specimens of mortar referred to was determined by DRX, of this an account was given in (3).
In the cases studied it was evident that there is produced an increase of Ca (II) in the dissolution of the new solid phases, and likewise of the value of pH, which depend on the mixture utilized for the manufacture of the different series of test specimens of mortar and on the time of conservation-attack. Said quantities of Ca (II) experience, for each age, a strong decrease, if the quantity of cement 1 of the mixture is less, and an increase, for each mixture, if the time of conservation-attack is increased; this increase is mild for the case of the means in which there have been submerged the test specimens made with the mixtures which have the greater content of slag (60 and 70%) in weigh. If, moreover, there is borne in mind the content of Ca (II) in the artificial sea water ASTM, the process of dissolution of Ca (II) is additive.
The content of Mg (II) of the artificial sea water ASTM(443 X 10-2 mols./800 ml) experiences in all the cases studied a decrease which is a function of the mixture utilized in the manufacture of the different series of test specimens of mortar and of the time of conservation-attack, which have an influence in the conditions of the means and, in a special manner, in the concentration of the groups OH (I). The ion Mg (II) has practically disappeared from the artificial sea water in which there have been submerged the test specimens of mortar made with cement 1 and with the mixture which has 15% of slag, in weight; in the remaining means there has been detected the ion Mg (II) in variable quantities according to the mixture utilized in the preparation of the test specimens. The ion Mg (II) has been found in the new solid phases formed in the artificial sea water in which there have been submerged the series of test specimens manufactured with cement 1 and with the mixture which has 15 % of slag; it has precipitated as brucite.
The content of SO4 (II) of the artificial sea water ASTM (2.44 X /10-2 mols./800 ml) has likewise experienced a decrease which depends on the mixture utilized in the manufacture of the test speciments and on the time of conservation-attack; in the new solid phase there has been found the ion SO4 (II) in quantities less than 0.06 X 10-2 mols. When the contents of slag of the mixtures referred to are raised (60 and 70%, in weight) the contents of SO4 (II) experiment minimum variations.
On the contrary, in the content of Cl (I) in the means, (artificial sea water) in which there have been the test specimens of mortar, there is an influence, in a special manner, of the slag in the mixture utilized to manufacture the series of test specimens; the minimum content of said ions Cl (I) corresponds to the case of the mixtures which have 35 and 60% of slag.