AGGREGATE BASE 303.03
301.05 Method of Measuremen T — Vacant
301.06 Basis of Payment
The Department will consider the cost of water to be included in the contract unit price for the appropriate existing Base pay item.
303.01 Description
This work consists of providing and placing one or more layers of aggregates, and specified additives, on a prepared subgrade or subbase using conventional equipment and methods for incorporating water into th e aggregate base material and spreading it onto the subgrade. When plant mixed aggregate base is required by the Contract, the work will be performed by incorporating water into the aggregate base material with specialized equipment and methods away from the subgrade, and using specialized equipment for spreading the aggregate material onto the subgrade.
303.02 Materials
Provide aggregate material for the gradation type shown on the Plans (Type A, Type B, or Type C) in accordance with Subsection 703.01, “Aggregate for Aggregate Base.” Do not change the approved gradation type or source during aggregate production, unless the Engineer approves another gradation type or source in writing.
303.03 Equipment
A.Stationary Plant Provide a central mixing plant of the pugmill type, rotary drum type, or continuous type of mixer. Establish stationary plant location within reasonable proximity to the project in order to deliver the aggregate base material at the proper moisture and consistency requirements.
B.Traveling Plant Provide a traveling plant of the type that picks up the material from a windrow or from a blanket of loose material. The mixer may be of the pugmill or auger type, or of the transverse shaft type that mixes the materials by means of revolving paddles that lift all the loose material from the working area. Ensure the traveling plant has provisions for introducing the water at the time of mixing, through a metering device, or by other approved methods, and can apply the water by means of controls which will supply a uniform ratio of water in the approximate amount required for optimum moisture.
303.04 Aggregate Base
178 Ensure the device by which the mi xing machine picks up the material can be controlled and operated on each pass of the mixer as to pick up all the material to be treated, and at the same time avoid cutting into the working area.
C.Compactor Provide a self -propelled, steel wheeled compact or weighing at least 10 ton [9 metric ton].
303.04 Construction Methods
A.Preparation of Subgrade Prepare the subgrade in accordance with Subsection 310.04.B, “Subgrade Method B for All Other Subbases, Bases, Pavement, or Surface,” or as required by the Contract.
B.Preparation of Existing Base Course Prepare existing aggregate base course in accordance with Section 311, “Processing Existing Base and Surface,” or as r equired by the Contract.
C.Mixing Aggregate Base When the aggregate is required to be plant mixed, uniformly mix the aggregate base materials and water using a stationary or traveling plant at locations away fro m the subgrade to achieve a uniform material near optimum moisture. Use of on -grade mixing methods for the aggregate base and water will only be allowed for a recycled concrete pavement generated within the project or in other special circumstances approv ed in advance by the Engineer. When the aggregate is not required to be plant mixed, uniformly mix the aggregate base materials and water using a stationary or traveling plant at outside locations, or using on -grade mixing methods to achieve a uniform mate rial near optimum moisture. On -grade mixing methods must not cause instability to the underlying subgrade material due to moisture saturation. If instability is caused, the methods must be suspended and improved to eliminate that condition.
1.Stationary Pl ant Uniformly mix the aggregate and water in an approved central mixing plant (pugmill, rotary drum, or continuous mixer). Add water during the mixing operation to achieve the proper moisture content for compaction in accordance with Subsection 303.04.E, “Compaction. ”
2.Traveling Plant Perform the following steps to uniformly mix the aggregate and water using a traveling plant: Clean the specified area of vegetation and deleterious materials. Overlay the specified area with at least 3 in [75 mm] of base material and compact to achieve a work table for mixing operations. If the mixing machine requires a blanket of material, spread the windrow to a uniform depth and width consistent with the machine’s capability. Add water during the mixing operation to achieve the proper moisture content for compaction in accordance with Subsection 303.04.E, “Compaction.” Avoid using excess water during mixing and compaction to prevent undue softenin g of the subgrade. AGGREGATE BASE 303.04 Ensure the device used to pick up the material does not contaminate the mixture by cutting into the work table. Continue mixing until the aggregate and water are evenly distributed and a uniform mixture is produced, meeting specification requirements. Adjust the mixing equipment to prevent material from moving in a longitudinal direction during the mixing process.
3.On-Grade Mixing Moisten the base material during the mixing of the aggregate base material and water, as close to optimum moisture content as practical before its placement to minimize the amount of water that must be uniformly mixed on the subgrade. Apply additional water as needed accurately and uniformly throughout the length of the section being placed so that no excess wet or dry spots exist in the finished aggregate base. Avoid application of excess water, during both mixing and compaction, so that undue softening of the subgrade will not develop.
D.Spreading
1.General Transport the mixed aggregate base materials (n on-plant mixed) to the roadbed and place using equipment and methods that will not damage the underlying subgrade or separator fabric. Spread the aggregate base material so that once compacted, the base will be within acceptable tolerances to the final sl ope and elevation shown in the plans. Make adjustments to equipment and methods as needed to: minimize segregation and degradation of aggregate base material, provide sufficient moisture content of aggregate base material (near optimum moisture content) w ithout over saturating the underlying subgrade material, and obtain final slope and elevations within acceptable tolerances. Place aggregate base material in layers of from 4 in to 8 in [100 mm to 200 mm] compacted thickness. Spread and compact the aggrega te base material over the full width of the roadbed before placing a succeeding layer. Finish compacted layers to the grades, elevations, and thicknesses shown on the Plans. Correct segregated areas at no additional cost to the Department. Stagger longi tudinal and transverse joints at least 1 ft [0.3 m] in each succeeding layer. Minimize disturbance to the surface of the previously placed layer when constructing successive layers of aggregate base. Adjust placement procedures or equipment to ensure comp liance with the Contract.
303.05 Aggregate Base
180 (2) Spreading Requirements for Plant Mixed Aggregate Transport the non -segregated aggregate base material that is near optimum moisture content to the roadbed then place using equipment capable of spreading the material in a single operation to the final slope and elevation , such as an asphalt lay -down machine. An alternate method of spreading may be used when one of the following conditions exists: Plan quantities for aggregate base material less than 2,5 00 cubic yards [1,900 cubic meters]. Aggregate base width is too narrow or variable for the use of the spreading equipment. Aggregate base material used for temporary pavements, shoulders, and county roads. Aggregate base is placed on an untreated subgrade . Aggregate base material is recycled concrete pavement generated within the project. Other conditions as noted in the plans.
E.Compaction Compact each layer to the proper density: no less than 98 percent of maximum density for Type A Aggregate Base, and 95 percent for Types B and C Aggregate Base. Determine maximum density in accordance with AASHTO T-180, Method D. Measure the in -place field density in accordance with AASHTO T -310; direct transmission is the preferred method (rod projected into base as opposed to back -scatter mode). Provide sufficient moisture content in the aggregate base material at the time of placement near the optimum moisture content to enable proper compaction. Prevent damage to aggregate particles during compaction. Moisture content will aid in the base compaction, reduce the compactive effort necessary, and minimize the breakdown of the gradation of the material. If during compaction the moisture content drops below optimum moisture such that the required percent compaction cannot be obtained, apply water uniformly over the base materials as needed to ensure a uniform texture, firmly keyed aggregates, and proper co nsolidation of layers. Cure the aggregate base material such that there is no free standing water before applying the prime coat or the succeeding layer of aggregate base or pavement section. If the density required by the Contract is achieved, the Depar tment will not consider moisture content as an acceptance criterion.
F.Tolerances Finish the aggregate base in accordance with Subsection 301.04.A, “Tolerances.”
303.05 Method of Measuremen T
The Engineer will measure the volume of the compacted in -place Aggregate Base Type A , Type B , and Type C by multiplying the completed length of aggregate base by the area of the typical section shown on the Plans. CALICHE BASE 305.04
303.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit:
A.AGGREGATE BASE TYPE A Cubic Yard [Cubic Meter]
B.AGGREGATE BASE TYPE A, PLANT MIXED Cubic Yard [Cubic Meter]
C.AGGREGATE BASE TYPE B Cubic Yard [Cubic Meter]
D.AGGREGATE BASE TYPE B, PLANT MIXED Cubic Yard [Cubic Meter]
E.AGGREGATE BASE TYPE C Cubic Yard [Cubic Meter]
F.AGGREGATE BASE TYPE C, PLANT MIXED Cubic Yard [Cubic Meter] SECTION 305 CALICHE BASE
305.01 Description
This work consists of constructing a base of approved deposits of calcareous and siliceous material constructed on the prepared subgrade.
305.02 Materials
Provide materials in accordance with Subsection 703.09, “Caliche Base.”
305.03 Equipment — Vacant
305.04 Construction Methods
A.Preparation of Subgrade Prepare the subgrade in accordance with Subsection 310.04.B, “Subgrade Method B for All Other Subbases, Bases, Pavement, or Surface, ” before placing the new subbase and base course material on the roadbed. Pulverize the existing surface and base materials and place the materials to establish the new subgrade in accordance wi th Section 311, “Processing Existing Base and Surface, ” or as shown on the Plans.
B.Mixing and Placing If material is to be combined and blended on the roadbed, deliver weighed material and place it in measured windrows, each in the proper proportions before blending. Do not exceed the amount that can be uniformly mixed by the equipment on the project during one day's operation.
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 191–194 of 935.