3-22 Section 306. Aggregate Surface Course and Maintenance Gravel
306.01 Description
This work consists of constructing aggregate surface course on a prepared subgrade or existing aggregate surface.
306.02 Materials
Provide materials in accordance with the following sections : Dense-Graded Aggregate 21A, 21AA, 22A, 23A, 23AA ........................ 902 Salvaged Aggregate .............................................................................. 902 Provide Dense -Graded Aggregate 21A, 21AA, or 22A if the plans show aggregate surface course later receiving a paved surface. Provide Dense-Graded Aggregate 23A or 23AA if the plans show construction of aggregate surface without a paved surface. Provide Dense -Graded Aggregate 21A, 21AA, 22A, 23A, 23AA, or salvaged aggregate for temporary maintenance gravel.
306.03 Construction
A.Preparation of Base. When requ ired, blade, or scarify and blade, existing aggregate surfaces to remove irregularities in the grade.
B.Placing and Compacting . Provide a ticket with each load stating the following information:
1.Project number ;
2.Aggregate source;
3.Aggregate series ;
4.Date;
5.Time ;
6.Truck identifier number ;
7.Supplier name; and
8.Type of aggregate approval. If the contract requires payment by weight, ensure the ticket includes gross weight, tare weight, and net weight to the nearest 100 pounds. Determine the truck tare weight at least once daily. If the contract does not require payment by weight, the Engineer may accept written documentation instead of tickets. Written documentation MDOT Standard Specifications for Construction Section 306 3-23 must identify the pay item of the material and include all of the information listed above except time and truck identifier number. Provide a uniform aggregate mixture, compacted in place to a uniform density full depth. Provide a complete surface course to the line, grade, or cross section as shown on the plans. Place maintenance gravel at driveway an d intersection locations as shown on the plans or as directed by the Engineer to provide a flush transition to driveways, intersecting cross streets, and adjacent surfaces where maintaining traffic. Grade maintenance gravel to provide positive drainage. Match the existing widths of the driveways and intersections as shown on the plans or as directed by the Engineer. When construction operations progress to a point that maintenance gravel is no longer needed, as determined by the Engineer, remove the maintenance gravel on the same day as paving of the removal area. Remove and dispose of maintenance gravel in accordance with the standard specifications. If approved by the Engineer, the Contractor may leave maintenance gravel in place as part of the work. Do not place aggregate on unstable surfaces , as determined by the Engineer. Maintain the aggregate in a smooth and stable condition until removed, surfaced, or project completion. Compact the aggregate layers to a uniform thickness no greater than 8 inches. If placing HMA surface over the aggregate surface course, compact each aggregate layer to at least 98% of the maximum unit weight at a moisture content no greater than optimum. For other aggregate surface course applications, compact each layer of aggregat e to at least 95% of the maximum unit weight at a moisture content no greater than optimum. Grade the finished surface and layers to within ±½ inch of the crown and grade shown on the plans. If placing aggregate base in a layer no greater than 3 inches, co mpact using pneumatic -tired rollers or vibratory compactors to at least 95% of the maximum unit weight at a moisture content no greater than optimum.
C.Use of Additives. The Contractor may use additives to facilitate compaction and for dust control.
306.04 Measurem ent and Payment
Pay Item Pay Unit Aggregate Surface Cse, __ inch .................................................... Square Yard Aggregate Surface Cse ........................................................... Cubic Yard, Ton MDOT Standard Specifications for Construction Section 306 3-24 Maintenance Gravel, LM .................................................................. Cubic Yard Maintenance Gravel ..................................................................................... Ton Driveway Maintenance, Commercial ........................................................ Each Driveway Maintenance, Residential .......................................................... Each Intersection Maintenance .......................................................................... Each
A.Aggregate Surface Course. The Engineer will measure Aggregate Surface Cse, __ inch by the width and length shown on the plans. The Engineer will determine the moisture content and pay weights as specified in section 109. If the contr act requires weight measurement, the Engineer will measure Aggregate Surface Cse by the scale weight, including additives, at a moisture content no greater than 8% . The Engineer will perform moisture tests at the start of weighing operations and when const ruction operations, weather conditions, or other causes may change the moisture content of the material. If tests indicate a moisture content greater than 8% , the Engineer will deduct the weight of the excess moisture from the scale weight of the aggregate until moisture tests indicate the moisture content is no greater than 8 %. The unit price for Aggregate Surface Cse, __ inch and Aggregate Surface Cse includes the cost of additives and water.
B.Maintenance Gravel . The Engineer will measure Maintenance Gravel, LM based on hauling unit dimensions and load count before placement and compaction. The unit price for Maintenance Gravel, LM includes the cost of constructing, maintaining, and removing the aggregate surface. The Engineer will measure Maintenance Gravel in tons by the scale weight of the material. The Engineer will perform moisture tests at the start of weighing operations and if construction operations, weather conditions, or other causes may change the moisture content of the material. If tests indicate a moisture content greater than 8 %, the Engineer will deduct the weight of the excess moisture from the scale weight of the maintenance gravel until moisture tests indicate the moisture content is no greater than 8% . The Engineer will determine the moisture content and pay weights as specified in section 109.
C.Driveway Maintenance, Commercial; Driveway Maintenance, Residential and Intersection Maintenance includes construction, grading, maintenance, removal , replacement , and disposal of the aggregate surface. These items will be paid for once per location MDOT Standard Specifications for Construction Section 306 3-25 regardless of the number of times the aggregate surface is placed, maintained, removed, or replaced. Intersection Maintenance will be paid for separately for each approach of the highway, street , or alley that joins or crosses the roa dway.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 197–200 of 1,146.