EXAMINATION OF BITUMINOUS ROAD MATERIALS. 

 VOLATILIZATION TEST. 



EQUIPMENT. 



1 constant-temperature hot-air oven with rubber tubing. (Fig. 11.) 



1 thermo-regulator. (Fig. 11-a.) 



2 chemical thermometers reading from —10° C. to 250° 0. 



1 tin box, 6 centimeters in diameter by 2 centimeters deep. 



1 analytical balance, capacity 100 grams, sensitive to 0.1 milligram. 



The object of the volatilization test is to determine the percentage 

 of loss which the material undergoes when 20 grams in a standard- 

 sized container are subjected to a uniform temperature of 163° C. for 

 five hours, and also to ascertain any changes in the character of the 

 material due to such 

 heating. 



The oven shown in 

 figure 11, known as 

 the New York Test- 

 ing Laboratory oven, 

 is used by the Office 

 of Public Roads and 

 Rural Engineering, 

 although any other 

 form may be used 

 that will give a uni- 

 form temperature 

 throughout all parts 

 where samples are 

 placed. The bulb of 

 one of the thermometers is immersed in a sample of some fluid, non- 

 volatile; bitumen, while the other is kept in air at the same level. 

 The first thermometer serves to show the temperature of the samples 

 during the test, while the latter gives prompt warning of any sudden 

 changes in temperature due to irregularities in the gas pressure, etc. 



Before making the test the interior of the oven should show a tem- 

 perature of 163° C. as registered by the thermometer in air. The tin 

 box is accurately weighed after carefully wiping with a towel to 

 remove any grease or dirt. About 20 grams of the material to bo 

 '1 is then placed in the box. The material may then be weighed 

 on .t rough balance, if one is at hand, after which the accurate weight, 

 which should not vary more than 0.2 gram from tho specified amount, 

 i- obtained. It may be necessary to warm some of the material in 

 order to handle it conveniently, after which it must be allowed to 

 cool before determining the accurate weight. 



Fig. 11. — New York Testing Laboratory oven. 



