M.w YORK STATE Ml BEUM 



tlv of the Bame Bize, and have the sides exactly parallel 

 nll ,l ,i , atctly perpendicular to them. This is only ob- 



tainable when large cubes are used, and these require great ma- 

 chines to crush them, 



M. <; ;ir; , 5 i that in order to obtain agreement between 



different compression tests, the specimens should be made by 

 . and gives the following directions. 



Pate iiu> grams ill oui E cement and 1200 gram- ! L2.2 



our dr^ standard sand, mix thoroughly in a dish, add L60 



of water, and work the resulting mortar 

 thoroughly for five minute- (quicksetting cements are to be 



rked bin one minute). Put 860 grains (30.3 ounces) of tins 

 in.. riar into the cubic mold properly provided with filling ca 

 ami fastened to the bed plate. The iron core is placed into the 



mi, and L50 blows are delivered on it by means of the hammer 

 apparatus, with the hammer of 2 kilograms (-11 pounds) weight. 

 The filling cases and core having been removed, the specimen is 

 struck off Hum, smoothed and drawn off the bed plate together 

 with the mold. 



For neat cement specimens, mix about 1000 grams (2.2 pounds) 

 cement with the requisite amount of water. The molds should 

 be oiled a little, and can be removed only after the cement has 

 sufficiently hardened, which is usually from 20 to 24 hours after 



making. 



While the elasticity of Portland cement decreases after some 

 r8j and the tensile strength ceases to grow after a similar 

 period, it- compressive resistance increasi 



The machines used for determining the compressive strength 

 are similar to those employed for the crushing of building stones 

 and bricks. The compression test is seldom carried out in the 

 United States. 



Tensile strength 



To carry out this test the cement is mixed with water to the 

 consistency of a Btiff paste and formed into briquets, this being 

 done by means of bra— molds. 



When the cemenl alone is used it is'spoken of as "neat" ce- 

 ment. When mixed with Band the term "cement mortar" is 



1 Trms. Am. BOO. civ. <-riK- :i(): -•">• 



