ENGINEERING RESEARCH INSTITUTE THE UNIVERSITY OF MICHIGAN ANN ARBOR Final Report (Appendix III) A COLOR-CODED BAR GRAPH SHOWING CHANGE IN ASPHALT DUE TO EXPOSURE R.. A, Leger Supervisor L-aboratory. Operations W. M. Aldous Project Engineer Project 2249 THE OHIO OIL COMPANY FINDLAY, OHIO May 1957

The University of Michigan ~ Engineering Research Institute A DISCUSSION OF THE COLOR-CODED BAR GRAPH The color-coded bar graph is employed to facilitate a rapid appraisal of the test data. Especially significant test results have been shown. Aggregate mixtures and exposures as included cover a considerable range of conditions. Each test asphalt is identified by a distinctive color, and its respective bar is placed in an appropriate column to facilitate comparison between the percent change of each asphalt. The ability of an asphalt to resist change in composition or test properties is considered to reflect its internal stability. Throughout this investigation, the minimum variation from the properties of the original material has been accepted as evidence of a more favorable performance of the recovered asphalt after exposure. Such change, either an increase or decrease from the original test value, is reported as a percent of the original. The results shown by the bar graph were derived from asphalts which were subjected to selected laboratory exposure and limited outdoor weathering. The data indicate the relative internal stability of the asphalts, which is important when probable service behavior is considered. Their relationship to actual paving performance has not, however, been established. The percent change values resulting from exposure conditions for the several tests are related. Change in the fractional components, asphaltenes, oily constituents, and resins, are reflected in resultant test values and the magnitude of their percentage change. Previous testing of asphalt recovered from paving indicates that when the percent change in softening point and penetration, expressed as a softening point/penetration ratio, increases to values above 450 percent of the original material, the paving begins to develop a dry, lifeless appearance, map and shrinkage cracking is evident, cohesion and ductility decrease, and raveling is in the process of development. When the increase of percent change becomes 600 percent, the deterioration of the paving surface is accelerated and progressive. The exposures (a) and (al) to (n) increase in severity. When no value is given for a particular asphalt, exposure tests were not made. In general, an increased percent change in the resin/asphaltene ratio is accompanied by a corresponding change in the other test properties. Difference in the magnitude of change between the three test asphalts is usually not great; Lion, Leonard, and Trumbull show favorable resistance in the order named. 1

The University of Michigan ~ Engineering Research Institute The initial and supplemental test results after (n) exposure, indicate its severity. A comparison of the recovered asphalt from defective paving as reported in Progress Report 1,4 ERI Project 2249, Field Inspection and Laboratory Tests on Asphalt and Asphalt Pavements, indicates that the (n) exposure produces test results similar to those for asphalts recovered from defective paving. As to the spot-test characteristics of recovered asphalt, the results using Skelly "S" and xylene-heptane solvent indicate that (n) exposure tended to change an intially negative Leonard and Trumbull to partially or completely positive. It is also apparent that changes in the fractional components sufficient to produce an unbalance in the structure of the original asphalt result in heterogeneity, and that such a condition is manifest by the positive spot characteristics of the affected material. 2

PERCENTAGE CHANGE IN RECOVERED ASPHALTS FROM MIXTURES WITH VARIOUS AGGREGATE UNDER DIFFERENT CONDITIONS OF EXPOSURE Identification of Symbols Used in Graph Mat'1 Heating Mix Time I Mixture Heating_ Agg Asphalt Hobart, Time, Temp, I~ ~ Test Conditions Exposure m mm FO of Oven m ai 350 300 1 50 325 F. Draft Cool 45 mmn, extract and recover. h 350 300 1 90 325 F. Draft Cool 45 min, extract and recover. k 350 300 1 30 325 F. Draft Loose spread in shallow pan, expose 60 days outdoors. Dry at 1500F to remove moisture. Cool, extract, and recover. l 350 300 1 30 325 F. Draft Compact mixture to 4" diameter x 4-1/2" cylinders, expose 60 days outdoors, ^ dry at 150OF to remove moisture. Cool, extract, and recover. n 350 300 1 180 325 F. Draft Loose spread in shallow pan, heat to 3250F in force draft oven. Cool, extract, and recover. -I Note: Numbers in spot bars on graph show number of samples for a specific spot condition. Test results on asphalt recovered from Michigan and Minnesota aggregate mixtures are combined in the columns headed penetration, softening point, and softening point/penetration ratio. Numbers shown near the top of any bar graph column represent total percent change which exceeded the percentage scale. Such numbers are color-coded to indicate the asphalt to which they are applicable. Aggregate 1 - Ottawa Sand Leonard Asphalt - Red Aggregate 2 - Local Sand Lion Asphalt ~ Blue Aggregate 3 - Michigan Material Trumbull Asphalt ~ Green Aggregate 4 - Minnesota Material