Standard and tentative methods of sampling and testing highway materials : recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, , Feb 23-27, 1920 . , the material is too viscous forthe hydrometer method, and the pycnometer method should be employed. The direct specific gravity reading obtained by the foregoing method is based uponwater at ° C. taken as unity. For all practical purposes this reading may becorrected to water at 25° C, considered as unity, by multiplying it by Thus:Specific gravity 25° ° gravity 25°
Standard and tentative methods of sampling and testing highway materials : recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, , Feb 23-27, 1920 . , the material is too viscous forthe hydrometer method, and the pycnometer method should be employed. The direct specific gravity reading obtained by the foregoing method is based uponwater at ° C. taken as unity. For all practical purposes this reading may becorrected to water at 25° C, considered as unity, by multiplying it by Thus:Specific gravity 25° ° gravity 25° B. PYCNOMETER METHOD (USED FOR VISCOUS FLUID AND SEMISOLID BITUMENS AND EMULSIONS). The inconvenience and difficulty of employing the ordinary narrow neck pyc-nometer when determining the specific gravity of viscous fluid and semisolidbitumens has led to the use of a special form shown in figure U. S. DEPARTMENT OF AGRICULTURE BULLETIN NO. 949. Standard and Tentative Methodsof Sampling and Testing HighwayMaterials. Errata. P. 37. Change the formula for specific gravityto read c-a Specific gravity ° (h-a)-(d-c) SAMPLING AND TESTING HIGHWAY MATERIALS. 37. This pycnometer consists of a conical or Erlenmeyer-shaped flask about , cm. diameter at bottom, and cm. diameter at the mouth. It is care-fully ground to receive an accurately fitting solid glass stopper with a hole about 1 in place of the usual capillary opening. The lower surface of this stopper is madeconcave to allow air bubbles to escape through the bore. The depth of the cup-shapeddepression is mm. at the center. The flask has a capacity of about 25 c. c. andweighs when empty about 25 grams. Its principal advantages are (1) that any de-sired amount of bitumen may be poured in without touching the sides above the de-sired level; (2) it is easily cleaned; (3) on account of the mm. bore the stoppercan be easily inserted when the flask is rilled with a v
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectroadmat, bookyear1921
