190 ANNUAL REPORT 
TESTS OF PORTLAND CEMENT. 
The cement shall stand the following tests; any that fails to meet 
these tests will be rejected and the contractor shall immediately remove 
the same from the work. 
Soundness. —Two pats of neat cement, with thin edges, will be made 
upon glass plates, and allowed to attain permanent set in moist air. 
Twenty-four hours after making, one pat will be placed in water having 
a temperature between 50 and 70 degrees F., and must withstand indefinite 
exposure without checking, softening or distortion. The other pat will 
be placed in some form of a steamer over cold water, which shall be 
brought to the boiling point and maintained at this temperature for three 
hours and then allowed to cool slowly. The pat shall not show any signs 
of distortion, cracking or softening under this test. 
Fineness, —The cement shall be so finely ground that after being 
thoroughly dried by heating it 94 per cent. shall pass through a No. 100 
standard sieve, woven from No. 40 Stub’s wire guage. 
Activity. —Initial set shall not occur in less than 40 minutes, and 
final set in less than one hour and 30 minutes nor more than six hours. 
The time of setting shall be determined by Gilmore’s wires, or Vicat’s 
needle. | 
Tensile Strength. —The standard section of briquette shall be used. 
The neat cement shall be mixed into a rather dry, stiff paste by the addition 
of from 17 to 20 per cent. of its weight of water. In a mortar of sand 
and cement, water to the amount of 10 to 13 per cent. of their combined 
weights shall be used, the amount depending upon the character of the 
cement and sand. The mortar shall be firmly pressed into the molds 
with the thumbs, filling the molds in three layers of about equal thickness 
and smoothing off both sides with a trowel. Briquettes shall remain in 
moist air for twenty-four hours and the remainder of the time, until 
tested, they shall remain in water at a temperature of about 60 to 65 
degrees F. | 
Seven day tests of neat cement shall show not less than 450 pounds 
per square inch, and not less than 550 pounds for 28 day tests. Briquettes 
made of I part cement to 3 parts standard sand shall stand a test of 150 
pounds per square inch at seven days. | 
SPECIFICATIONS FOR SAND. 
All sand used for mortar shall pass a No. 10 sieve and 80 per cent. of 
it shall be retained upon a No. 74 sieve. It shall be a silicious sand, as 
sharp as can be obtained within reasonable limits of cost. It shall be free 
from all vegetable and organic matter, and shall not contain more than 
Io per cent. by weight, of clayey or loamy material. 
