CONCRETE CONSTRUCTION IN THE PHILIPPINE ISLANDS. 129 



Concrete cubes from Naga River Bridge, Province of CcbuA 



Dimensions, in inches. 



Propor- 

 tions, by 

 volume. 



Age. 



Total strength, 

 in pounds. 



Strength, in 

 pounds, per 

 square inch. 



Mark on cubes. 



First 

 crack. 



Ulti- 

 mate. 



First 

 crack. 



Ulti- 

 mate. 



5. 95X5.95X 5.95 





Days. 

 28 



19,570 

 14, 740 



18,505 

 925 



272 

 135 



527 

 271 



Class A. 

 Class B. 







"The appearance of these cubes showed that the mixture employed was an improper 

 one, as there was not enough mortar present to fill the voids properly. The mortar was 

 also weak and easily broken with the fingers, and had an unnatural, brown color. It is 

 possible that impurities such as clay prevented the hardening of the cement. 



Concrete cubes tested as per "Bequest No. 68328" gave erratic results 

 which were attributed to excess of sand and to the poor grading of the 

 gravel. Very little of the gravel was found to be cracked in any of 

 the crushed cubes, but its granularmetric composition was extraordinarily 

 poor. With the exception of several stones 2.5 to 3 inches in diameter, 

 the gravel was of a uniform size. Fine gravel to reduce the voids was 

 lacking. 



The results obtained were the following : 



Compression tests of concrete cubes per Request No. 



Dimensions, in inches. 



5| X 6i X 6 . 

 6X6J X6-. 

 6X6X6- 



fi X H X 6.. 



5J X 6* X 6 



5{ X6X6-. 



Class. 



A" concrete 



.___do 



._._do 



____do '. 



'B" concrete 

 -_._do_. 

 'C" concrete 



Age. 



Total strength, 



in pounds, per 



square inch. 



Total strength, 



in pounds, per 



square inch. 



First 

 crack. 



Ulti- 

 mate. 



First 

 crack. 



Ulti- 

 mate. 



Days. 











37 



42, 970 



54, 295 



1,194 



1,508 



37 



35, 000 



52, 570 



972 



1,460 



37 



54, 450 



60, 060 



1,512 



1,670 | 



43 



26, 250 



36, 210 



730 



1,006 



44 



14, 500 



37, 300 



403 



1,042 



44 



27, 420 



34,310 



762 



953 



23 



8,470 



34, 220 



235 



945 



Mark on cubes. 



'A" floor. 



Do. 



Do. 

 'A" pier. 

 "B" pier. 



Do. 

 "C" No. 2 pier. 



When a good aggregate and a proper mixture had been employed, the 

 concrete gave much better results. A few samples are here recorded 

 for comparative purposes. 



