364 ANNUAL REPORT 
Krdmenger’s Table Showing Effect of Various Salts on the 
Behavior of Portland Cements. 
Sulmlence || Timelotening | | Tete a 
added. | - minutes. ke. per sq.cm. | kg. per sq. em. 
B | 2 SON oS 
Cement alone. . 10 minutes. | 40.8 13}.83 
Percent added) 27 5 %o sy ale oni 17a) Nn. 72 oP eka aN 
law gypsum...| 240 | 360 360 | 56.5 | 62.6 | 26.4 | 19.9 | 
Potass. sulphate! 4 | Z| eles [So 4 oe 2G, 0 fp 1358 
Sodium sulph’te LE dee | 5 | 43.2 | 46.0 | 43.2 | 19.4 | 19.0°| 
Ammon stip: 120 300 | 480 | 54.4 | 35.3 [15.1 | | 
Magnes. sulph.| 15 | 480 | 24hrs. | 48.1 | 87.1.| 46.3 | 15.5 | 14.3 
Amat, ulin) Ge fam) ao. bao 40.0 | 34.3 | 16.4 | 16.7 
Iron sulphate.. | 360 | 720 | 240 | 48.0 | 41.9 | BYR) ul Lbs) 3) 
Ame oO RD Ar |p| 2. | 18 | 
Caustic potash. MBO | palaces Cas | Pe Wewlaeel Mois | 15.1 | 
Ammonium.... | | | | | | 
Inv, clix@xel Gl © peel ad eet nia een nat eee eee sha Aes) | | UG 8 
some Portland cement mortars were destroyed at an alarming rate in 
sea water, and consequently a vast mass of literature exists on this 
point and the data collected are exceedingly contradictory and con- 
fusing. However, thanks to the work of the German Portland Cement 
Manufacturers’ Association, some light has been thrown on the action of 
sea water, and though the experiments carried on by this society ‘on a 
large scale are not yet finished, it is known now that there is little 
danger for sea water work if the mortar is made dense and good Port- 
land cement is used. 
The supposed destruction of Portland cement concrete is said to 
be due to the magnesium content of sea water and formation of calcium- 
aluminum sulphates. The alumina is said to be especially injurious 
and gypsum also is a source of danger in this respect. Rebuffat ascribes 
the partial solution of the cement to the formation of sulfo-aluminates. 
Michaelis and Vicat think that the action is based on the reaction: 
Ca(OH),4+-MeSO,=Me(OH),+CaSO, 
which, owing to the formation of crystalline calcium sulphate, causes an 
