PORTLAND CEMENT TESTING. 



163 





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lb 



Fig. 9. 



Fig. jo. 



Tliis surface!- is made of steel and of tlie form shown in ligs. 9 and 10. The 

 Hat surface c fits loosely into the mold. The layer of cement is placed into the 

 latter, distributed a.s evenly as possible with the fingers, and then lightly pressed 

 together with the siu'facer. Treating each layer in this manner also keeps the 

 material from sliding and working around during tamping. 



To secure uniform effects of tamping it is also essential that the suc- 

 cessive layers of each briquette be made as nearly equal as possible. 

 This is easily attained l)y the use of a small beaker as a measure. After 

 selecting a beaker of the correct capacity it is scooped full of cement^ 

 the excess shaken off^ and the remainder turned into the mold. 



It is not advisable in mortar manipulation to use a measure; the 

 mortar adheres to the glass to some extent and, in dumping, the sand 

 readily falls out, Ijut some cement paste remains attached to the beaker, 

 thus changing the ratio of 1 to 3. We quickly form the mortar into a 



