46 



BULLETIN {>49, U. S. DEPARTMENT OF AGRICULTURE. 



It is sometimes necessary to make several trials before the desired result is obtained, 

 When the required penetration is reached, the residue left from evaporation is weighed 

 and its per cent of the original sample taken is computed. 



29. TEST FOR PENETRATION OF BITUMINOUS MATERIALS. 



(A. S. T. M. Standard Method, Seriai Designation: D 5-16.) 

 I. DEFINITION. 



(1) Penetration is defined as the consistency of a bituminous material expressed as 

 the distance that a standard needle vertically penetrates a sample of the material 

 under known conditions of loading, time, and temperature. Where the conditions 

 of test are not specifically mentioned, the load, time, and temperature are understood 

 to be 100 grams, 5 seconds, 25° C (77° F.), respectively, and the units of penetration 

 to indicate hundredths of a centimeter. 



Z2S 



Fig. 24. — New York Testing Laboratory penetrometer. 

 II. APPARATUS. 



(2) The container for holding the material to be tested shall be a flat-bottom, cylin- 

 drical dish, 55 mm. (2^- inches) in diameter and 35 mm. (If inches) deep. 8 (See 

 figs. 24 and 25.) 



(3) The needle ° for this test shall be of cylindrical steel rod 50.8 mm. (2 inches) 

 long and having a diameter of 1.016 mm. (0.04 inch) and turned on one end to a 

 sharp point having a taper of 6.35 mm. (one-fourth inch). 



(4) The water bath shall be maintained at a temperature not varying more than 

 0.1° C. from 25° C. (77° F.) The volume of water shall be not less than 10 liters and 

 the sample shall be immersed to a depth of not less than 10 cm. (4 inches) and shall 

 be supported on a perforated shelf not less than 5 cm. (2 inches) from the bottom of 

 the bath. 



s This requirement is fulfilled by the American Can Co.'s gill style ointment box, deep pattern, 3-ounce 

 capacity. 



3 It is recommended that the Roberts No. 2 parabola needle be used until such a time as Committee D-4 

 of the American Society for Testing Materials are in a position to make a recommendation relative to a 

 type of needle which may generally be obtained. 



