BTSW YORK 3TATB MUSEUM 



mixed dry in ■ vessel, and nio can of water are added ther< 

 and then the mortar is thoroughly mixed for five minutes, of 

 this mortar B50 grama are placed in the cubic molds, provided 

 with guide mold, and the m<dd is then Bcrewed on the bedpL 

 under the pounding machine. Hie iron follower is placed in 

 tin- form, and, by means trip bammer, 150 blows 



ruck, by a hammer weighing 2 kilograms. 

 After removing the guide mold and follower, the test piece is 

 tothed off, with the mold from the bedplate, and for the rest 

 - for hand work, as given above, 



MAKING TEST 1'IECES 1 [TEAT CEMENT 



The inside of the moldfl is slightly oiled, and the same are 

 placed on a metal or glass plate without blotting paper. 1000 

 gra nient are weighed out, 200 grams of water are 



added, and the whole mass thoroughly mixed for live min- 

 utes (best with pestle). The forms are well filled (rounded), 

 and then proceed as for hand work as given above The 

 molds can only be taken off after the cement has sufficiently 

 hardened. Since, by the pounding in of the n<-at cement, I 

 pieces of uniform consistency are to be obtained, for finely ground 

 or quick setting cements, the amount of water must be corre- 

 adingly increased. The volume of water is always to be 

 stated in giving the Btrength obtained. 



TREATMENT OF TEST PIECES AT TIME OE TESTING 



All specimens are to be tested directly after their removal from 

 the water. Since the time of testing is of influence on the result 

 in tensile tests, the increase of load shall be 100 grams 

 per Becond. The mean «»f the four best results shall be consid- 



l the final tensile strength. In testing compression piec 

 the pressure is always to be exerted on two side faces of the cube, 

 bm a the bottom or top. The mean of the four highest t< 



sidered as the final compressive strength. 



Abstract from French specifications for Portland cement 

 CHEMICAL ANALYSIS 



Til- ent must nol contain more than "K of sulfuric acids 



terminable proportion. Cements containing more 



than 1 ad, or in which the ratio of the combined silica 



and alumina to the lime is lc.>- than A \. are to be regarded as 

 doubtful. 



