OPEN -GRADED BASES 319.04 OPEN -GRADED BASES
319.01 Description
This work consists of constructing a permeable base course, which includes the following: Mixing aggregate and bituminous material or aggregate, portland cement concrete, and water in a central plant, and Spreading and compacting the mixture on a prepared surface.
319.02 Materials
Provide materials in accordance with Section 708, “Plant Mix Bituminous Bases and Surfaces,” and the following subsections: Material: Subsection: Aggregate 703.03 Water 701.04 Fly Ash 702.01 Portland Cement 701.02
319.03 Equipment
Use equipment for producing, heating, mixing, hauling, spreading, compacting, and finishing the Open - Graded Bituminous Base (OGBB) in accordance with Subsection 411.03, “Equipment.” Use equipment for producing, mixing, hauling, spreading, compacting, and finishing the Open -Graded Portland Cement Concrete Base (OGPCCB) in accordance with Subsection 301.03, “Equipment,” and Subsection 414.03, “Equipment.”
319.04 Construction Methods
A.General
1.Prime Coat Apply a prime coat in accordance with Section 408, "Prime Coat." if required by the Contract.
2.Tolerances Finish open -graded bases in accordance with Subsection 301.04.A, “Tolerances. ”
3.Hydraulic Efficiency Construct and maintain a hydraulically efficient open -graded base. Perform a hydraulic efficiency test 24 hr before placing the overlying pavement. Do not place overlying pavement until achieving acceptable hydraulic efficiency, defined as 1 qt [1 L] of water absorbed into the base surface with no remaining standing water 15 sec after pouring. Remove and replace open -graded
319.04 Open -Graded Bases
200 base that fails to achieve acceptable hydraulic efficiency as directed by the Resident Engineer, at no additional cost to the Depart ment. Ensure that soil, mud, or other materials are not tracked, spilled, or washed onto the open - graded base. Repair damage to the open -graded base as approved by the Resident Engineer, at no additional cost to the Department.
B.Open -Graded Bituminous B ase (OGBB) Construct OGBB in accordance with Subsection 406.04, “Construction Methods, ” with the following exceptions:
1.Weather Limitations Construct OGBB in accordance with Subs ection 411.04.H, "Temperature and Weather Limitations."
2.Construction Traffic Do not allow c onstruction traffic on the OGBB until the OGBB has cooled overnight and do not place overlying pavement on the OGBB until the curing period is complete. Limit c onstruction traffic on the OGBB; do not use OGBB as a haul road. Repair damage as approved by the Resident Engineer, at no additional cost to the Department.
C.Open -Graded Portland Cement Concrete Base (OGPCCB) Ensure the following construction requireme nts are met: The mix has a cement content of at least 240 lb/yd³ [142 kg/m³]. Limit fly ash substitution to no more than 28 percent of the required cement, maintaining a substitution ratio of 1 lb [1 kg] of fly ash per 1 lb [1 kg] of cement. The water to c ement ratio is no greater than 0.45, calculated using the following equation: where CW/ = Water to cement ratio, W = Weight of water (measure the amount of water mixed into the batch, plus the free water on wet aggrega te, minus the water absorbed by dry aggregate), C = Weight of cement, and F = Weight of fly ash. The Resident Engineer will review and approve the water to cement ratio calculation.
1.Mixing and Placing Mix and place OGPCCB in accord ance with Subsection 414.04.C, "Mixing Concrete," Subsection 414.04.E, "Setting Forms," and Subsection 414.04.F, "Placing Concrete." ) /( / FCWCW OPEN -GRADED BASES 319.05
2.Weather Limitations and Maintenance Quality Do not mix OGPCCB if the aggregate or subgrade is frozen. Mix and place OGPCCB when the ambient air temperature is at least 40 °F [5 °C] and rising. Protect and maintain the quality of the base after its placeme nt and approval by the Resident Engineer. Ensure repairs yield a uniform and durable surface; replace low areas and other flaws for the full depth of the base. Maintain and repair the OGPCCB at no additional cost to the Department.
3.Base Ensure the subgrade is uniformly moist at the time of the OGPCCB placement.
4.Consolidation of Mixture Consolidate the mixture using vibratory equipment during lay -down operations to achieve at least 95 percent of density (unit weight) as determined in accordance with AASHTO T 121. Measure the consolidation of the finished OGPCCB from 15 min to 30 min after placement and consolidation using a nuclear density gauge in accordance with AASHTO T 310.
5.Water Curing Cure the completed OGPCCB by directing a fine spray of water onto the surface every 2 hr, for a period of 16 hr. Begin curing immediately after its initial set, when water no longer removes cement paste.
6.Construction Joint Prepare construction joints in the OGPCCB by c utting back the edge of the base to create a vertical face. Replace material removed to create the construction joint, at no additional cost to the Department.
7.Traffic Restrictions and Curing Period Do not allow construction traffic on the OGPCCB, except the paver. Ensure the 3 -day c uring period is complete before placing pavement layers on top of the OGPCCB. Place material for succeeding layers using the side discharge method.
319.05 Method of Measuremen T
The Resident Engineer will measure the area of in -place Open -Graded Bituminous Base and Open - Graded Portland Cement Concrete Base completed to the thicknesses shown on the Plans.
325.04 Separator Fabric for Bases
319.06 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.OPEN -GRADED BITUMINOUS BASE Square Yard [Square Meter]
B.OPEN -GRADED PORTLAND CEMENT CONCRETE BASE Square Yard [Square Meter] The Department will pay for Prime Coat in accordance with Section 408, "Prime Coat." SECTION 325 SEPARATOR FABRIC FOR BASES
325.01 Description
This work consists of installing a separator fabric for bases.
325.02 Materials
Provide separator fabric in accordance with Subsection 712.05, "Geotextiles for Bases."
325.03 Equipment — Vacant
325.04 Construction Methods
A.Shipping and Storage Provide separator fabric in wrapper that will protect the fabric from ultraviolet radiation and abrasion from shipping and handling. Label each roll to identify each product for inventory and quality control. In the field, store and protect the fabric rolls from the elements.
B.Installation Before placing fabric, ensure the subgrade is smooth and free of obstructions t hat may damage the fabric. Place the fabric smooth, straight, and free of wrinkles at the locations shown on the Plans. Overlap each transverse joint of fabric (between rolls) with the end of the preceding roll placed above the beginning of the succeeding roll at least 17 in [430 mm]. Place and cover the fabric with base material on the same day. Apply at least 4 in [100 mm] of base material by end dumping. Fill and compact ruts in the base material. Repair damaged fabric in sections that meet the speci fied overlap requirements, at no additional cost to the Department.
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 213–215 of 935.