Find the amount of asphalt required for this project.Solution:Estimates for Asphalt PlantsThe amount of materials comprising the plant mixcan be best determined by a proportionate method. Thisis demonstrated by the following example:Example: The required tonnage of plant mix for aproject is 800 tons. The aggregate blend is 50/40/10(percentage coarse aggregate/fine aggregate/mineralfiller). The bitumen contentis 6 percent. How many tonsof each aggregate are required?The job mix formula is as follows:= Adjusted Percent of AGGOAC = Optimum Bituminous (Asphalt) ContentSolution:Total aggregate percent by weight= 100 – 6 = 94percent, or 0.94.Coarse/aggregate = 0.94 x 50 percent = 47.0 percentby weight of the total mix.Fine aggregate = .094 x 40 percent = 37.6 percentby weight of the total mix.Mineral filler = 0.94 x 10 percent = 9.4 by weightof the total mix.To convert to tons, multiply the required tonnage ofplant mix by the percentage of each component of themix. The results should be adjusted so that the sum ofthe tonnage of components is equal to the requiredtonnage of plant mix.Coarse aggregate = 800 x 0.470 = 376.0 tonsFine aggregate= 800 x 0.376 = 300.8 tonsMineral filler= 800 x 0.094 = 75.2 tonsBitumen= 800 x 0,060 = 48.0 tons800 tons(The bitumen weight was calculated as a check.)Tons per hourThe equation used to compute the amount of asphaltthat can belayed with a paver per hour is as follows:Tons per hour =LxWxDx1462000x 6 0Where:L= Feet per minute. The NCF uses 11 feet perminute for planning purposes,W= Width of the paver screedD= Depth or thickness of compacted mat146 =This number represents the approximateweight of 1 cubic foot of compactedhot-mix asphalt60= 60 minutes in one hour2000 = There are 2,000 pounds in 1 tonExample: The required tonnage of hot-mix asphaltfor a project is 800 tons. The screed of the paver is setat 10 feet, and the depth of asphalt is 2 inches. Estimatethe amount of asphalt that can be laid per hour.Solution:11x10x.167x146x60= 160921.22000 2,000160921.22,000= 80.46 tons per hourBy planning and estimating the amount of hot-mixasphalt that can be laid per hour, you are able to tell theasphalt plant exactly how much hot-mix asphalt isrequired to be delivered per hour and/or per day.8-33
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