T44 2^EW YOKK STATE MUSEUM -- 



parts are lime and alumina, and, the grinding of tlie vitrified 

 material to a fine powder. 



1 Packing and weights: As a rnle Portland cement is to be 

 packed in standard barrels of 180 kilograms (397 pounds), gross 

 weight, and. about 170 kilograms (374 pounds), net weight, and 

 in half standard barrels of 90 kilograms (198 pounds), gross 

 weight and about 83 kilograms (133 pounds), net weight. The 

 gross weight is to be marked on the barrels. If the cement is 

 called for in bags or barrels of other weight, the gross weight of 

 the same must be clearly marked upon the packages. Losses 

 and variations in weight of the single packages up to 2/^ of the 

 same will be allowed. Barrels and sacks, in addition to the 

 weight shall show in legible writing the name and trade mark 

 of the manufacturer. 



2 Time of setting : Slow or quick setting cement may be called 

 for according to the use for which the cement is to be put. Ce- 

 ments which do not set in less than 2 hours, are to be considered 

 slow setting cements. 



3 Constancy of volume : Portland cement shall be of constant 

 volume. As a preliminary test, admitting of forming a rapid 

 opinion, the heating test is recommended. The decisive test shall 

 be that a paste of neat cement made on a glass plate protected 

 against drying and placed under w^ater after 24 hours, shall not 

 show after the lapse of a longer period of time any blowing cracks, 

 or change of shape. 



4 Fineness of grinding: Portland cement shall be so finely 

 ground that a batch of the same shall not leave a residue of more 

 than 10^ upon a sieve of 900 meshes per square centimeter (5806 

 meshes per square inch). The thickness of the wire of the sieve 

 shall equal half the space between the wires. For test 100 grams 

 (32 ounces) of cement shall be used. 



5 Tests of strength : The cohesive power of Portland cement 

 shall be determined by the testing of a mixture of cement and 

 sand. The tests shall be both tensile and compressive, made 

 according to a uniform method, with test pieces of the same form 

 and cross-section, and with the same apparatus. At the same time 

 a determination of the strength of the neat cement is to be recom- 

 mended. 



6 Tensile and compressive strength: Good slow setting cement, 

 in the proportion of three parts by weight of standard sand to 

 one part of cement shall have when tested, after 28 days' hard- 

 ening (one in air and 27 in water), a minimum tensile strength 



