•PROPERTIES OF PORTLAND CEMENT. PART III. 



221 



Table XXIII. — Characteristic setting properties of the commercial Portland 

 cements brands 0, K and L. 



Brand. 



Fineness. 



Characteristics of chemical con- 

 stituents (samples ignited). 



Characteristics of the setting properties. 



200 

 mesh. 



100 

 mesh. 



Com- 

 bined 

 SiOj. 



AI0O3. 



FCaOs. 



CaO. 







K 

 L 



77.0 



88.0 

 75.0 



96.0 



98.0 

 92.0 



Low 

 (20. 2Q) 



Normal 

 (20. 50) 



Normal 

 (22.00) 



High 

 (8.50) 



Low 

 (4.90) 



Normal 



(6.50) 



Normal 

 (2.95) 



High 



(4. 00) 



Normal 



(3. 30) 



Normal 

 (63. 00) 



High 



(66.00) 



High 



(66.00) 



When the cement is rather heavily plas- 

 tered the initial and final sets are usually 

 normal and stable, averaging about 1 

 hour 10 minutes and 2 hours 20 minutes, 

 respectively. When lightly plastered the 

 cement is either quick setting or very apt 

 to become so when exposed to the atmos- 

 phere, j 



The setting of this cement is very difficult 

 to retard. Even when rather heavily 

 plastered an extremely rapid initial and 

 final set may be characteristic of the 

 cement. (See Table A.)5o 



Whether heavily or lightly plastered the 

 setting of this cement has always been 

 found to be normal and stable. The ini- 

 tial set occurs in about 2 hours and 30 

 minutes, and the final in about 5 hours 30 

 minutes. Late shipments of this cement 

 are ground much finer than formerly, 

 but the cement still retains the above 

 characteristics in its setting properties. 



These clinkers corresponding to the cements given in Table XXIII vs^ere first 

 crushed in a jaw crusher and then ground to the recorded fineness in -an iron, 

 air-tight ball-mill charged with sixty manganese iron balls weighing in all about 

 18 kilograms. 



One of these manufacturers also gave us 150 kilograms of cement (classified 

 as brand d in the following work) which was ground at tlie factory from a 

 20-ton sample of hard-burned rotary clinker taken just as it had left the kiln 

 except that it had been allowed to cool sufficiently to be sent to the crushers. 



Fortunately, these samples all contained little more than a trace of sulphuric 

 anhydride (SO3) namely 0.10, 0.14, 0.14 and 0.15 per cent for brands 0, d, K, 

 and L, respectively. Therefore, they could be considered as practically free from 

 calcium sulphate. , 



'This Journal, Sec. A (1910), 5, 415. 



