130 



REIBLING. 



Concrete cubes from Bayaoas River Bridge.'- 



Dimensions, in inches. 



Class. 



Age. 



Total strength, 

 in pounds, per 

 square inch. 



Strength, in 

 pounds per 

 square inch. 



Mark on cubes. 



First 

 crack. 



Ulti- 

 mate. 



First 

 crack. 



Ulti- 

 mate. 



6 X 6.1 X 5.9 



6. 1 X 6. 1 X 5. 9 .. 



"A" concrete 

 _ _ do 



Days. 

 29 

 29 

 29 

 26 

 26 

 29 



23, 980 

 19,180 

 29, 850 

 41,990 

 31, 790 

 29, 550 



62, 980 

 66, 090 

 68, 575 

 63, 495 

 63, 770 

 60, 265 



655 

 516 

 802 

 1,164 

 866 

 807 



1,720 

 1,775 

 1,840 

 1,762 

 1,743 

 1,666 



A 1. 

 A 2. 

 A3. 

 B 1. 

 B2. 

 B3. 



6.1 X 6.1 X 5.9 



_ _ do 



6.1 X 5.9 X 6 



6.0 X 6.1 X 5.9 



6.0 X 6.1 X 5.9 



"B" concrete 



do 



do 







"Gravel was very good, and very few broken stones were found in the crushed concrete. 



Compression tests. 



Mark on cubes. 



Age in 

 days. 



Dimen- 

 sions, in 

 inches. 



Initial 

 crack. 



Ultimate 

 strength. 



Strengthen 

 pounds, per 

 square inch. 



Propor- 

 tion. 



First 

 crack. 



Ulti- 

 mate. 



Class "A" concrete from con- 

 crete used in R. C. piles, Pan- 

 tal Bridge, LL-3, Pnngasinan, 

 October 16, 1909. 



Average 



28 



6X6X6 



,42,900 

 1 39, 000 

 ] 60, 000 



(44, 000 



51,000 

 50, 100 

 62, 000 

 52, 930 



1,192 

 1,083 

 1,666 

 1,222 



1,417 

 1,392 

 1,722 

 1,470 



1:2:4 

 1:2:4 

 1:2:4 

 1:2:4 



46, 425 



54,000 



1,291 



1,500 



. 







The above cubes were well proportioned, the mortar as well as the concrete 

 contained few voids. Very few broken stones were found. The aggregate is 

 composed of a standard cement, Santa Barbara sand, and Sual Well gravel. The 

 cubes were kept constantly moist under wet cloth. 



Plate II is a photograph of the third concrete cube recorded in the above 

 table. About 70 stones were exposed on the surface of the crushed cube. 

 Of these, only two small pebbles were cracked. The strength of the 

 stone was greater than that of the mortar. The photograph shows cracks 

 in the mortar in many places. 



Such analytical results and conclusions lead to the assumption that 

 by synthetic reasoning we could foretell the value and strength of a 

 concrete by a careful study of the aggregate from which it is to be made. 

 For instance, we would not expect that soft, coral, rock concrete would 

 possess good strength despite a proper mixture and a rich strong mortar, 

 as we would assume that the soft stone would limit the strength of the 

 concrete to a very low figure. We would also assume that if harder 

 coral rock were substituted for the softer material the resulting concrete 

 would be stronger. Accordingly, soft and hard coral 1:2:4 concrete 

 was manufactured ; and when tested gave the following average results : 



