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STATE GEOLOGIST. 213 
brand and the name of the manufacturer. Any packages broken at the time 
of delivery may be rejected, or used as half packages at the option of the 
Engineer. 
45. Weight. —Ordinarily ten per cent. of the packages in each carload lot 
will be selected for weighing and testing. The average net weight of all 
packages in each carload lot will be the average net weight of all the selected 
packages. The failure of any one of the selected packages to stand the 
required tests will be sufficient reason for the rejection of this carload lot, 
in the discretion of the Engineer. Rejected cement will be branded and 
immediately removed from the work. 
46. Fineness, —Of Portland cement, ninety-eight per cent. (98%) by weight 
must pass through a cement wire sieve having 2,500 meshes per square inch, 
made of No. 35 wire, S. W. G., and ninety-five per cent. (95%) by weight must 
pass through a sieve having 10,000 meshes per square inch, and made of No, 
40 wire, S. W. G. 
47, Test Briquettes.—Test briquettes for Portland cement will be made 
both neat and in proportions of one cement to three of sand. Enough watery 
only will be used to thoroughly moisten the mixture, which will be forced 
into the mold by pressure or tamping, so as to give as nearly as possible the 
density of good concrete work. The temperature of the water and of the 
room in which the briquettes are made and tested will not be permitted to fall 
below 60 degrees Fahrenheit. The sand used in preparing all briquettes shall 
be clean, sharp, crushed quartz, retained on a sieve of thirty meshes per 
lineal inch, (holes 0.022” square) and passing through a sieve of twenty 
meshes per lineal inch (holes 0.033” square.) 
48, Initial Set and Hot Water Test.—Cement mixed neat with about 22 
per cent. of water to form a stiff paste, shall not begin its initial set for forty 
minutes after mixing with water and after sixty minutes it must be appre- 
ciably indented by the end of a wire one-twelfth inch in diameter, loaded to 
weigh one-quarter pound. Cement made into thin cakes on glass plates 
shall not crack, scale nor warp under the following treatment: Three pats 
will be made and allowed to harden in moist air at from 60 to 70 degrees 
temperature; one of these will be subjected to water vapor at 176 degrees 
temperature for three hours, after which it will be immersed in hot water 
forty-eight hours; another will be placed in water at from 60 to 70 degrees tem- 
perature; and the third will be left in moist air. 
49, Tensile Strength, The tensile strength will be determined by the 
average strength of three briquettes of neat cement and the average 
strength of three briquettes of cement and sand. These will be kept 
in moist air until set, and then immersed in water until they are put into the 
clips of the testing machine, being tested wet. Briquettes prepared from 
neat Portland cement shall, after seven days, develop a tensile strength of 
not less than 450 pounds per square inch, and after 28 days not less than 550 
pounds per square inch. Briquettes prepared from a mixture of one part 
Portland cement and three parts sand (parts by weight) shall, after seven 
days, develop a tensile strength of not less than 125 pounds per square inch 
and not less than 200 pounds per square inch after 28 days. Briquettes pre- 
pared from a mixture of one part Portland cement and three parts sand 
(parts by weight) and immersed, after 24 hours, in water maintained at 170 
degrees Fahrenheit, shall not swell nor crack, and shall, after seven days, 
develop a tensile strength of not less than 150 pounds per Square inch. 
