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Sent By: LOUCKS ASSOCIATES , INC. ; 612 424 5822; Nov-26-01 6:33AM; Page 3/4 • I ROAD DESIGN MANUAL JANUARY 31, 1982 DESIGN POLICYAND CRITERIA( ' Table 7-6.031 7.5.03,03 Granular Equivalent (G. E.) Factors For layer thicknesses have been established, total pavement I Aggregate Base Design thickness and layer composition is determined. Granular equivalency factors provide a means of equat- 11 ing the structural performance of all bituminous and 7-5.03.04 Full-Depth Bituminous Pavement Design aggregate courses which make up a pavement structure in terms of the structural performance of a well-known Full•depth asphalt pavement is defined as a pavement MI 1 high-type aggregate base (e.g., Mn/DOT Class 6 Aggregate structure in which asphalt mixtures are employed for all Base), The granular equivalency concept is a convenient courses above the subgrade or improved subgrade. This am way to define or rate a pavement structure for purposes of type of.structure is composed of an asphalt surface course II comparison, and it forms the basis for the Mn/DOT Bitu- and one or more asphalt base courses supported by the urinous Pavement Design Chart, Figure 7 5.03A. subgrade. Preparation of full-depth asphalt pavement mixtures shall be in accordance with the Mn/DOT Standard i The G. E. required (expressed in inches) for the pave- , Specifications. This type of pavement structure was ap- ment structure design is the product of Minnesota Invests- proved and included as a design alternate for Minnesota in gation No. 183 (1969), which defined required G. E. 1978. 111 in terms of Stabilometer R-value and Sigma N-18 accumu- lated damage effect at a point where repetitions of traffic The principal factors to be evaluated for the structural loadings reduced pavement structure to a specific level of design of a full-depth asphalt pavement are: Traffic con- di service defined as a Present Serviceability Index of 2,5. ditions throughout the design period; subgrade and other in By definition this is a surface condition at which trunk available construction materials;and environmental factors highways will require a structural overlay to restore rida- which may affect pavement behavior or service. bility and load support capability. The design of a full-depth asphalt pavement is a function After the required G. E.is determined,it is converted to of the same variables as bituminous pavement with aggre actual minimum thickness of surfacing,base and subbase by gate base. These are 1-way design-lane AADT. 20 year means of the appropriate granular equivalent factor found design•lane Sigma N•18/20,and design R Value. 1111 in Table 7-5.031. These factors are a function of the type withflexible pavement with a99regate base, an es- of material and its intended use. Once these minimuan11, Table 7-5.031 GRANULAR EQUIVALENT(G.E.) FACTORS' I Material Specification G.E.Factors Plant-Mix Surface 2341, 2361 '3• — 2 3? s- 25 -I.5 41 Plant-Mix Surface 2331 2.00 ' • Plant-Mix Binder 2331 • 2.00 Plant-Mix Base 2331 q ¢-" 2.00- Z. Road-Mix Surface 2321 �'� 1.50 Road-Mix Base 2321 —7.31 1.50 Bituminous Treat. Base (Rich) 2204 1.50 4 Bituminous Treat. Base (Lean) 2204 '} 1.25 •-e- Aggregate Base (Cl. 5,Cl-6)3138 r. figl —1.00 • Aggregate Base (CL 3,Cl.4) 3138 0.75 Selected Granular Material 0.50* :7'. VFW G.h Fl v.,:(z,:, 41A45 ✓� . ',tl *May be used in design when so approved by the Subgrade and Base Design Engineer. NOTE: Where the subgrade consists of granular material, the District Materials and/or Sails .r, may recommend the treatment of the upper portion of the selected granular material lbs/sq yd or more of stabilizing aggregate (Specification 3149,2C). ':