232 



REIBLING AND REYES, 



slight extent. In the first place prolonged, thorougli aeration failed to 

 eliminate the power of the commercial or selected material to set, unless 

 the time of exposure was carried far beyond that required to convert the 

 hydrated lime into calcium carbonate. For instance, the non-plastered 

 cement described in Table XXVIII sets in fifteen minutes after being 

 thoroughly aerated for three months and the commercial plastered 

 cements (Table XXII) all retain a normal initial set after similar treat- 

 ment. Then too, it was found that when the seasoned ceraents were 

 ignited at a low red heat, their original physical properties in this 

 respect again returned. Had the compounds which cause the cements 

 to set decomposed to any considerable extent it would have required 

 incipient fusion to restore their original setting properties. 



Another fact which tends to support the same conclusion is demon- 

 strated by the results obtained from the following experiment. 



Two samples, each consisting of 40 kilograms of the non-seasoned, thoroughly 

 mixed, hard-burned rotary clinker K were dumped into eoverless wooden boxes. 

 One of these was stored in the laboratory. The other was weathered outside 

 where the clinker was frequently wetted, it being the time of the local rainy 

 season. At the end of the three months these samples, together with the non- 

 seasoned clinker which had been preserved in a sealed glass jar, were each thor- 

 oughly dried and ground in the same ball mill to pass a 100-mesh sieve and to 

 as nearly the same degree of fineness as possible. The results of the tests are 

 shown by Table XXX and figure 19. 



Table XXX. — Physical and chemical properties of seasoned and non-seasoned, 

 hard-hwned, rotary clinker, brand K. 











Calorim- 













eter test 













(compar- 







Loss 



M. 



Igni- 

 tion. 



Specific 





ative 

 constant 

 lime fac- 

 tor or the 



rise in 

 tempera- 

 ture due 



Microscopic 

 test (relative 





gravity 





quantities of 



Character of test. 



(dried 



at 

 110°). 



Free lime. 



slaked lime 

 present in 

 the ground 











to the 



cement). 











slaking 













of free 













lime). 







Per ct. 







°C. 





Clinker stored in a air- 



0.62 



3.15 



Considerable CaO. Very 



3.0 



Very little. 



tight receptacle. 







little Ca (0H)2. 







Clinker aerated 3 



1.78 



3.10 



Very little CaO. Consider- 



1.0 



Considerable. 



months in an open 







able Ca(0H)2. 







wooden box stored 













in the laboratory. 













Clinker stored in an 



2.57 



3.07 



No CaO positively identified. 



0.7 



Considera b 1 y 



open wooden box 







Considerable Ca(0H)2. 





more than 



and weathered 3 











in the pre- 



months outside 











ceding sam- 



during the rainy 











ple. 



season. 













