204 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Temperature records of the percolating water were not kept, since these 

 tests represent a part of a larger series in which this would have been 

 impracticable. The other aggregates tested showed results from which it 

 was quite difficult to draw any legitimate conclusions as to the relative 

 suitability of different rocks in concrete subjected to these conditions. 



Concretes containing different aggregates. — A series of tests on con- 

 cretes made up of different aggregates but with the same cements gave 

 results which may be tabulated as follows : 



Table 14 



Flow in Grams of Water passing in 10 Minutes through Concrete Specimens 

 subjected to continuous Water Pressure for 52 Weeks 



Time 



Pressure, 

 pounds per 

 square inch 



Month 



Grams passing 



in 10 minutes 



Concrete with 



aggregate of 



crushed 



hardened 



neat cement 



Concrete with 



aggregate 



of crushed 



granite 



24 hours 



25 



January 



2111 



60 



1 week 



2 weeks 



22 

 22 



February . . 



836 

 662 



31 

 26 



3 " 



20 





626 



40 



4 " 



25 





570 



60 



5 " 



22 



March 



603 



62 



6 " 



20 





530 



50 



7 " 



20 





1295 



38 



8 " 



25 





1127 



40 



10 " 



12 " 



25 

 26 



April 



1310 



870 



45 



25 



14 " 



16 " 



24 

 24 



May 



997 



985 



36 



28 



18 " 



20 



June 



973 



32 



20 " 



17 





639 



20 



22 " 



20 





792 



40 



24 " 

 26 " 



17 

 22 



July. . . 



731 



802 



36 

 43 



28 " 

 30 " 



26 



22 



August 



800 

 781 



49 

 46 



32 " 



34 " 



20 

 19 



September. 



763 

 115 



50 

 Trace 



36 " 



26 



October. . . . 



105 



2 



38 " 



26 





107 



2 



40 " 



23 



November.. 



110 



3 



42 " 



25 





93 



2 



44 " 



22 



December. . 



75 



5 



46 " 



2L 





70 



3 



'48 " 



25 





80 



10 



50 " 



52 " 



20 

 20 



January 



73 



78 



7 . 

 7 



