230 



REIBLING AND REYES. 



The result of thoroughly aerating cement 0^ in an open shallow pan, 

 are given in Tables XXVIII and XXIX. 



Table XXVIII. — The effects of aeration on non-plastered, non-seasoned; 0, cemeiit. 



Time o 



(dried 

 atllO)°. 



Per 



cent in- 

 crease 



in 



volume 



per 



unit 



weight. 



Condition of the free lime 

 (microscopic test). 



Calorimeter 



test (rise in 



temperature in 



4 minutes). 



Per 

 cent of 

 water 

 requir- 

 ed to 



Time of 

 initial 



pro- 

 duce a 

 paste of 

 normal 

 consist- 



set in 

 min- 

 utes. 



ency. 





28.0 



200 



22.0 



10 



23.0 



5 



30.0 



15 



Remarks. 



3.19 



3.10 



3.07 

 3.04 



0.0 



2.9 



3.9 

 4.9 



Mostly calcium oxide 

 (CaO). 



No CaO. Slaked lime 

 [Ca(0H)2] inconsider- 

 able quantity. 



No CaO. A very little 

 slaked lime. 



No CaO. No Ca(0H)2. 

 Available free lime all 

 converted into calicum 

 carbonate. 



8°. 2 (constant 

 lime fac- 

 tor = 2°.0). 



0°.2 



0°.0 



0°.0 



A freshly set 

 r egauged 

 paste. 



A normal 

 paste. 



Do. 



Do. 



Table XXIX. — The effects of plaster on 0^ cement before and after its free lime 

 had become thoroughly hydrated. 









Per 













cent 











Calori- 



of wa- 









meter 



ter re- 







Cement. 



Per test 

 cent of (rise in 

 plaster |temper- 



quired 

 to pro- 

 duce a 



Time of 

 initial set in 



Remarks. 





added. aturein 



paste 











4 min- 



of nor- 











utes). 



mal 

 consist- 







• 







en ey.» 







Oi - - 



0.0 



8>^.2 



28.0 



Instantane- 



A freshly set regauged paste. 











ous (200 













regauged). 





Oi aerated 14 days 



0.0 



0°.2 



22.0 



5 



A normal paste. 



Oi 



0.5 



5°.0 



28.0 



Instantane- 

 ous (185 

 regauged). 



A partially regauged paste. 



Oi aerated 14 days 



0.5 



0°.0 



21.0 



185 



A normal paste. 



Oi - 



1.0 

 1.0 



2°.0 



o°.o 



21.0 

 21.5 



10 

 165 



Do. 

 Do. 



Oi aerated 14 days 



Oi 



1.5 



2°.0 



21.0 



45 



Do. 





» The figures in this column are computed by weight. The aerated cement has 2.9 

 per cent more absolute volume per unit weight than Ox non-seasoned. Therefore the 

 aerated cement requires less water by volume. 



Tables XXVIII and XXIX show that as soon as the free lime in 

 this cement had become thoroughly slaked, less water and less plaster 



