DIVISION 3 BASE COURSES 3.01 AGGREGATE BASE COURSE 3.01.01 Description This work shall consist of an aggregate base course constructed on an existing aggregate surface, on a prepared subbase, or on a prepared subgrade. 3.01.02 Materials The materials shall meet the requirements of Surfacing Aggregates 22A, as specified in Division 8.02 of the current edition of the Michigan Department of Transportation's Standard Specifications for Highway Construction. All aggregate base courses shall be crushed limestone. 3.01.03 Maximum Unit Weight Maximum unit weight, when used as a measure of compaction or density of cohesive materials, including aggregate bases and aggregate surfaces, having a loss by washing greater than 10 percent, shall be understood to mean the maximum unit weight per cubic foot as determined by AASHO T99, Method C, modified to include all materials passing the one-inch sieve. It may be further modified to allow one molded sample in conjunction with typical moisture-density curves developed by the MDOT. For aggregate bases and aggregate surfaces having a loss by washing of 10 percent or less, the maximum unit weight will be determined, at the moisture content between 4 and 8 percent, which will give the maximum unit weight, by the Standard Method of Test for Compaction and Density of Soils (Granular as described in Appendix D of the Soils Manual). 3.01.06 Preparation of New Subgrade These requirements apply to new locations or sections of the existing road that are changed in alignment or grade or both, or altered by subgrade undercutting or excavation of unsuitable material. The subgrade shall be smoothed and trimmed to the required line, grade and cross-section to receive the base course and shall be compacted to not less than 95 percent of the Maximum Unit Weight. The subgrade thus formed shall be maintained in a smooth compacted condition until the base course has been placed. No base course shall be placed on the subgrade until the subgrade has been approved by the Engineer. 3.01.07 Placing and Compacting New Material The finished subbase or subgrade shall be moistened with water through the use of a sprinkler truck or hose just ahead of any spreading of aggregate. Any rutting or distorting of the finished subbase or subgrade shall be corrected before the spreading of any aggregate. The aggregate shall be placed in uniform layers to such a depth, that when compacted, the course will have the thickness shown on the plans. The compacted depth of any layer shall not be more than 6 inches nor less than 3 inches. The aggregate shall be compacted to at least 98 percent of the maximum unit weight. The moisture content shall be maintained within a tolerance of plus or minus one percent of optimum until the prescribed unit weight is obtained. Each layer shall be compacted until the maximum unit weight is attained before placing the succeeding layer. Page 3.01-1 Revised 05-14 DIVISION 3 BASE COURSES 3.01 AGGREGATE BASE COURSE (Cont'd.) 3.01.07 Placing and Compacting New Material (Cont’d.) Additional water shall be applied when specified by the Engineer to aid compaction and shaping the road surface. The water shall be applied by means of approved sprinkler equipment. The surface course aggregate shall not be spread until the first course has been compacted to the satisfaction of the Engineer. The surface of the top course, after compaction, must conform to the required line, grade and cross-section as shown on the plans. 3.01.08 Maintenance of Aggregate Base The aggregate base course shall be maintained in a smooth, compacted condition, substantially true to line, grade and cross-section until surfacing is applied. The application of water or brine may be required when it is necessary to properly reshape the compacted surface, or to control dust, prior to the placing of the surfacing. 3.01.10 Method of Measurement Aggregate base shall be measured in area per square yard of base. 3.01.11 Basis of Payment Aggregate base shall be paid for at the Contract unit price per square yard, which price shall be payment in full for furnishing the aggregate, compacting, constructing and maintaining the aggregate base. Page 3.01-2 Revised 05-14 DIVISION 3 BASE COURSES 3.03 PATCHING PAVEMENT WITH BITUMINOUS MATERIAL 3.03.01 Description This work shall consist of patching the pavement surface where the pavement has been removed. 3.03.02 Materials The materials shall meet the following requirements of the current edition of the MDOT Standard Specifications for Highway Construction: Bituminous Concrete: Leveling or Wearing Course..........No. 12 The Contractor may certify that the bituminous mixture being furnished meets the above specification or the mixture may be visually inspected by the Engineer. Temporary patches may be made with any bituminous material readily available and approved by the Engineer. 3.03.03 Construction Methods Where patching is required, the compacted aggregate base course shall be leveled and trimmed to a depth 2" to 2 1/2" below the level of the existing pavement surface. The edges of the existing asphalt pavement adjacent to the area to be patched shall be squared and trimmed. A leveling course 1" to 1 1/2" shall be placed and compacted, followed by a wearing course of 1" minimum thickness when compacted. The surface of the patch shall be smooth and not vary more than 1/4" from the crown and grade of the adjacent pavement. 3.03.04 Method of Measurement Patching pavement with bituminous materials shall be measured by weight in tons. 3.03.05 Basis of Payment Patching pavement with bituminous materials shall be paid for at the contract unit price per ton, which price shall be payment in full for furnishing all the material, labor and equipment to patch the designated areas as shown on the plans or authorized by the Engineer, including preparation and trimming of previously placed aggregate base courses and adjacent pavement edges. No adjustment in contract unit prices will be made for increases or decreases in quantities, regardless of the percentage of increase or decrease. Page 3.03-1 Revised 05-14 .