Crepps, R B

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24 PURDUE ENGINEERING EXTENSION SERVICESPECIFICATIONS AND TESTS FOR BITUMINOUS ROAD MATERIALS.Discussion by Prof. R. B. Crepps,In Charge of Testing Materials Laboratory, Purdue University.The tests and specifications for bituminous materials for various types of pavements are becoming standardized through efforts of: The American Society of Testing Materials, The American Society of Municipal Improvements, The Asphalt Association and various public service bodies. The number of tests are being reduced to a practical working basis and while certain state highway commissions still maintain varied excep­tions to the proposed standard tests, most of these differences will soon be harmonized.The tests commonly specified are: penetration, flash point, loss on heating, penetration of residue, ductility and percentage of bitumen soluble in carbon tetrachloride.The penetration test is most important for consistency of asphalt in specifying the grade desired and controlling the man­ufacture.A much neded simplification as regards asphalt, (effective Jan. 1, 1924), has been brought about through the efforts of Mr. Herbert Hoover, Secretary of Commerce, and the various or­ganizations interested in its preparation and use. For paving purposes the penetration limits are reduced from 88 to 9 as fol­lows :Penetration LimitsSheet Asphalt .................  25- 30 30- 40 40- 50Asphaltic Concrete ......... 50- 60 60- 70 85-100Asphaltic Macadam andSurface Treatments ...100-120 120-150 150-200Joint fillers for various types of construction were reduced from 14 to 4 as follows:Penetration LimitsFor brick ................................ 35-50For admixtures of sand....... 50-60 60-70 85-100The mid point is desired in each case with an allowable tolerance to either limit.It is very important that correct sampling of materials be adhered to. Samples for testing should represent an average of the bulk. They should not be contaminated with dirt and should be properly marked for identification. A sample for laboratory tests should contain at least one quart of the bituminous ma­terial.

Specifications and Tests for Bituminous Road Materials

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Specifications and Tests for Bituminous Road Materials

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