132 



REIBLING. 



Gravel tests — Preliminary report. 





Specific 

 gravity. 



Voids 



(per 



cent). 



Ideal mix- 

 ture. 



Physical properties. 



Beach gravel . 



2.56 



2.47 

 2.68 

 2.62 



45.8 



46.3 



37.1 



»44.7 



1:1.73:3.6 



1:2:6 

 1:2:5 

 1:2:4 



Some stones are durable and hard, 

 but the majority are so weathered 

 as to disintegrate under slight pres- 

 sure. The efficiency of the gravel 

 for concrete is poor. 



Fine coral and shell gravel, not 

 coarse enough for gravel and too 

 coarse for sand. It is unsuitable 

 for concrete. 



Durable, hard beach gravel with 

 rounded and pitted surfaces. Good 

 concrete material if properly 

 graded. 



Hard and tough stone, which despite 

 its undesirable spally fracture is a 

 good concrete aggregate. 



No. 3 gravel 



No. 4 gravel 



No. 5stone (crushed Sisiman) 



a Graded. 

 Concrete tests (final report). 



CONCRETE CUBES. 



No. 



Dimen- 

 sions, in 

 inches. 



Propor- 

 tions, by 

 volume. 



Age. 



Total strength, 



in pounds, per 



square inch. 



Total strength, 



in pounds, per 



square inch. 



Hark on cubes. 



In 



moist 



air. 



In 

 air. 



First 

 crack. 



Ulti- 

 mate. 



First 

 crack. 



Ulti- 

 mate. 



1 



2 



3 

 4 



6X6X6. 



6X6X6- 

 6X6X6. 

 6X6X6. 



1:2:4 



1:3:6 



"1:1.73:3 



1-1:2:4 



Da ys . 

 7 



7 

 7 

 7 



Days. 

 21 



21 

 35 



35 



20, 800 



8,000 

 23, 840 

 19, 560 



41, 430 



28, 330 



56, 890 



4,500 



580 



222 

 662 

 543 



1,151 



800 

 1,560 

 1,250 



f Beach sand. 

 \Beach gravel. 



Do. 



Do. 



Do. 



a Ideal mixture. b Soft stone removed. 



Nos. 3 and No. 4 show a majority of the stone broken. Mortar good. 



6X6X6. 



6X6X6. 

 6X6X6. 



6X6X6. 

 6X6X6. 



6X6X6. 



1:2:5 



7 



21 



33, 835 



48, 845 



968 



1, 337 



{! 



1:2:4 



7 



21 



20, 130 



55, 500 



560 



1,540 



{ 



1 :3:6 



7 



21 



15, 215 



32, 495 



423 



903 





1:2:4 



7 



21 



47, 745 



75, 770 



1,326 



2,105 



{ 



1:3:6 



7 



21 



24, 660 



34, 715 



685 



964 





1:2:6 



7 



21 



16,820 



25, 580 



468 



710 



{ 



No. 4 gravel. 

 No. 2 sand. 

 No. 5 stone. 

 No. 1 sand. 



Do. 

 No. 5 stone. 

 No. 2 sand. 



Do. 

 No. 3 gravel. 

 No. 1 sand. 



