ECKEi..] UTILIZATION OF IRON AND STEEL SLAGS. 
Analyses showing composition of slag cements. 
223 
Constituent. 
Choindez, 
Switzer- 
land. 
Si0 2 _ 
ALO, - 
FeO ..... 
CaO .... 
MgO 
S 
SO, 
Loss on ignition 
19.5 
17.5 
54.0 
Donjeux, Saulnes, rhic . ai , T11 
France. France. cnicago, m. 
24. 85 
12.10 
3.85 
49.20 
1.75 
1.30 
1.35 
5.(55 
22. 45 
13.95 
3.30 
51.10 
1.35 
28. 95 
11.40 
0.54 
50.29 
2.96 
1.37 
Fnsley. 
Ala.' 
11.70 
51.71 
1.39 
1.31 
0.35 
7. 50 
3.39 
The composition of good slag cements may vary within the follow- 
ing limits: Silica, 22 to 30 percent; alumina and iron, 11 to 16 per 
cent; lime, 49 to 52 per cent; magnesia less than L per cent; sulphur, 
less than H per cent. It will be noted that the lime content is lower 
and the alnmina-iron content higher than in a cement of the Portland 
type. Slag cements also differ from Portland cement in being lower 
in specific gravity and lighter in color. Normally, they are slower 
setting than Portland cement, though this defect can be overcome by 
treatment during manufacture. They are deficient in resistance to 
mechanical wear, and do not set satisfactorily in dry situations. For 
use underwater or in permanently damp ground, however, they would 
seem to be of service. 
PORTLAND CEMENT FROM SLAG. 
True Portland cements, which must be sharply distinguished from 
the slag (pozzuolanic) cements discussed in the preceding section of 
this paper, can be made from mixtures of which one element is blast- 
furnace slag. In this case the slag is ground, intimately mixed with 
powdered limestone, and the mixture calcined and reground. Two 
plants are engaged in the manufacture of Portland cement from slag 
and limestone in the United States. An analysis of the "Universal" 
brand of the Illinois Steel Company, a Portland cement made from 
these materials, follows: 
Analysis of Universal brand, manufactured by the Illinois Steel Company. 
sicv_: 
Per cent. 
_. 23.62 
A1A 
CaO 
MgO 
so 3 _- 
s. ....__ 
Loss on ignition 
8.21 
2.71 
61.92 
1.78 
1.32 
None. 
0. 52 
