124 ‘The Philippine Journal of Science 1921 
For the granulometric test of gravel and crushed stone, a set 
of sieves was used having circular openings ranging in diameter 
from 2.25 inches down to 0.30 inch, namely 2.25, 1.50, 1.00, 0.67, 
0.45, and 0.30. Instead of wire cloth, these sieves consisted of 
sheet iron punched with round holes, which was soldered to a cir- 
cular frame 12 inches in diameter and 3 inches deep. 
A 2,000-gram. sample of the dry gravel was placed on the 
sievé with the largest opening and shaken by hand until no more 
of the material passed through. The material coming through 
this screen was placed on the sieve next smaller’in hole opening 
and the sieving performed as before, and the process continued 
with the other sieves in the series. The portions of aggregate 
remaining on each of the screens were weighed and recorded. 
Tensile and compressive strength tests.—The sands and screen- 
ings were tested for tensile strength in the proportions by weight 
of one part cement to three parts sand. Three-gang standard 
briquette molds were used for molding the test specimens. The 
briquettes were made in accordance with the directions pre- 
scribed in the United States Government specification for Port- 
land cement.* : 
Specimens for compression were made in the proportions by 
weight of one part cement to three parts sand, but in several in- 
stances the smallness of the sample precluded such a test. The 
compression specimens were cylindrical, with a diameter of 3.568 
inches and a height of 7.136 inches. The cylinder-shaped molds 
used in forming these test pieces are constructed of cast iron and 
are split vertically into halves for facility in removing the speci- 
mens. During the molding operation, the two halves of the mold 
are held together by a cast-iron ring that encircles the body of the 
mold with a taper fit. The diameter was made 3.568 inches so 
that the area of the bearing faces would be exactly 10 square 
inches, as this greatly facilitates the calculation of the strength 
per square inch. The height was made twice the least lateral 
diameter in order to secure the correct shearing angle during rup- 
ture. For the purpose of comparison briquettes and cylinders 
were molded of mortar composed of one part cement and three 
parts standard Ottawa sand, by weight. Both the tension and 
the compression test mortar specimens, unless otherwise noted, 
were stored for the first twenty-four hours in a moist-air cabinet; 
at the end of this period the test pieces were removed from 
the molds and stored up to the time of rupture in fresh run- 
ning water maintained at an average temperature of 28° C. 
* United States Government Specification for Portland Cement, Circular 
Bur. Standards 33 (May 1, 1912, and January 18, 1917). 
