Action of the salts in alkali water and sea water on cements. . ig. 12.— Weight of sulphuric anhydride precipitated or dissolved by various salts in contact with the set cement active in the first series, as shown in Figs. 1 to 5, in the presentseries removed per cent in 24 weeks and per cent in 78weeks in the first series, while the magnesium chloride-magnesiumsulphate solution in the present series removed per cent in24 weeks and per cent in 74 weeks in the first series. Othersimilar cases are noticeable from the table. 42 Technologic Papers of the Bureau of Standards The
Action of the salts in alkali water and sea water on cements. . ig. 12.— Weight of sulphuric anhydride precipitated or dissolved by various salts in contact with the set cement active in the first series, as shown in Figs. 1 to 5, in the presentseries removed per cent in 24 weeks and per cent in 78weeks in the first series, while the magnesium chloride-magnesiumsulphate solution in the present series removed per cent in24 weeks and per cent in 74 weeks in the first series. Othersimilar cases are noticeable from the table. 42 Technologic Papers of the Bureau of Standards The solutions sodium sulphate-magnesium sulphate and sodiumsulphate were removed from the cement and the tests discon-tinued when it was noticed that the sulphuric anhydride was nolonger being removed from the solution, but that which had beenremoved was redissolving. This was done in order to separatethe sulphate formed by heavy solutions and to obtain an analysisof the sulphate in the pure state. It was found, however, thatsuch separation was not 12 4 6 8 10 12 14 16 18 20 22 24 TIME IN WEEKS Fig. 13.—Percentage of magnesia precipitated by the set cement from various solutions In this series the effect of the changing of one of the salts in thesolution after the rate of solution had decreased is not as markedas with the unset cement. This would result largely because theprevious action before the change had been much more markedthan with unset cement. The results in this series, as shown in the tables and figures, donot need any further discussion beyond what has been said whendiscussing the unset cement, the same general effects of the solu-tions being noticeable in both cases. Action of Alkali and Sea Water on Cements 43 V. ACTION OF SEA WATER ON VARIOUS FRESH AND SET CEMENTS Some tests very similar to the preceding were inaugurated atthe laboratory at Atlantic City when work at that laboratorywas first started. The starting of these tests also antedated pre-c
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