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(2) Using the representative aggregate samples submitted by the Contractor and his proposed mixture proportions, gradations and trial mix tests will be conducted to evaluate the acceptability of the proposed aggregate blend and the (composite) gradation (which will be referred to as the Job-Mix Formula - J.M.F.) and to establish the percentage of asphalt cement (by weight of total mixture) to be used in production of the bituminous mixture. Mixture evaluation will be based on the trial mix test results and the corresponding requirements listed below. a) Trial Mix Tests* Test Properties Acceptable Range of valves Minimum Maximum Marshall Stability ,(75 blows) 1,000 pounds 3,000 pounds Air Voids** 4 percent 5 percent * Test procedures are on file in the Department of Transportation Materials Engineering Laboratory in St. Paul. ** A mixture with the air void content between 3.5 and 5.5 percent will be considered as satisfying these requirements. b) Asphalt cement content, as determined by the trial mix test procedures and the above criteria, shall not exceed 7.2 percent nor be .less than 5.5 percent (by total weight of mixture). If the bituminous mixture consists of 100 percent taconite, the above test property requirements for establishing the asphalt content shall not apply but, instead, the amount shall be as designated by the Engineer. The amount generally will be within the range of 7.0 to 7.5 percent (by total weight of mixture). c) The Contractor may elect to use a mixture resulting in an asphalt content that exceeds the maximum limit indicated above, but the Contract Agency will deduct the excess design asphalt from the pay quantity for bituminous material for mixture based on the difference between the maximum limit and the higher job-mix asphalt content. The difference will be deducted in all cases, even if the daily average of the -4-