Aug;. 13, 1917 



Toughness of Bituminous Aggregates 



325 



Table VII . — Percentages of weight of bitumens used in mixtures on basis of rational pro- 

 portion of 88 parts of mineral aggregate to 12 parts of bitumen 



Sample 

 No. 



loroi 



9093 

 10108 



9445 

 9095 

 9094 

 8136 

 8992 

 9321 



8993 

 8989 

 '9281 



Name of rock. 



Sand 



Diabase 



Biotite schist 



Ouartzite 



Biotite granite 



Biotite gneiss 



Altered diabase porphyry. . . . 



Sandstone 



Open-hearth slag 



Feldspathic quartzite 



Blast-furnace slag 



Chlorite gneiss 



Limestone 



Specific 



gravity 



of 



roclc. 



2. 65 



3- OS 

 2. 78 

 2. 67 

 2.65 



2-73 

 2.94 



2-54 

 3- 55 

 2. 67 



2-93 

 2-75 

 2. 72 



Percentage by weight. 



Refined water- 

 gas tar. 



X' 



5- 

 4- 



5- 

 5- 

 5- 

 5- 

 S- 

 5- 

 4- 

 5- 

 S- 

 5- 

 5-5 



Y' 



Oil 

 asphalt. 



Oil 

 asphalt. 



8950 



8949 



10 

 46 

 90 

 06 

 10 

 96 

 4. 62 

 31 



Oil 

 asphalt. 



Fluxed 

 native 

 asphalt. 



8948 



8748 



13 

 48 

 92 

 09 

 13 

 99 

 64 

 34 

 89 

 09 

 67 



95 

 02 



Table VIII. — Toughness tests on bituminous aggregate cylinders (second series) 



In direct reference to these service results a review of some of the data 

 developed in the two series of tests discloses some important relations. 

 It will be noted, for instance, that the limestone, blast-furnace slag, and 

 two chlorite gneisses show the lowest toughness of any of the rocks used 

 in the first series. In combination with certain bituminous binders, 



