CEMENTS. 
During the forthcoming field season all the important cement plants 
in the country will be visited, and a report on the cement industry in 
the United States will he published by the Survey. 
In addition to the paper presented below, a discussion of slag 
cements will be found on pages 221 to 223 of the present bulletin; 
while the manufacture of Portland cement from slag is discussed on 
pages 223 to 224. 
CEMENT INVESTIGATIONS IN ARIZONA. 
By Edward Duryee. 
INTRODUCTION. 
Investigations were made under instructions from Mr. J. B. Lippin- 
cott, of the U. S. Geological Survey, in order to ascertain means of 
lessening the cost of Portland cement in the construction of dams on 
the Gila River in Arizona. Owing to the remoteness of these pro- 
posed dams from lines of transportation, the expense of bringing 
cement to the sites makes a notable addition to the cost over con- 
struction elsewhere, and it is therefore of great importance to reduce 
the quantity of cement to the smallest allowable amount. 
Portland cement is considered an essential element in the construc- 
tion of dams subject to severe and sudden strains due to floods. It 
is valuable not only in giving great strength and homogeneity to the 
structure, but also because of the fact that exposure to moisture, 
which deteriorates many materials, serves to increase the strength of 
Portland-cement mortars. It is thus being largely used for this pur- 
pose. For example, the new dam under construction on the Nile at 
Assuan will require 3,000,000 barrels of Portland cement, costing, in 
round numbers, $12,000,000. 
The investigation of cement for the Gila River dams has been 
along three lines: (1) To ascertain whether by unusually fine grinding 
of the cement its strength can be appreciably enhanced and the 
quantity correspondingly reduced ; (2) whether it is feasible to use 
the rocks found at the dam sites for making a sand cement; (3) 
whether Portland cement can be economically made at these sites. 
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