290-1 Description.
Construct a granular subbase as a component of an optional base.
290-2 Materials.
Select one of the materials listed below and conform to the following requirements: Graded Aggregate ................................ ........................ 204-2 Limerock ................................ ............................. Section 911 Bank Run Shell ................................ ................... Section 91 1 Shell Rock ................................ ........................... Section 91 1 Cemented Coquina ................................ ..............Section 91 1 Recycled Concrete Aggregate (RCA)* ..............Section 911 *Do not use on interstate roadways.
290-3 Construction Methods.
For the subbase material selected, construct the sub base in conformance with the following: Graded Aggregate ................................ ............... Section 204 Limerock ................................ ............................. Section 200 Bank Run Shell ................................ ................... Section 200 Shell Rock ................................ ........................... Section 200 Cemented Coquina ................................ ..............Section 200 Recycled Concrete Aggregate (RCA)* ..............Section 200 *Do not use on interstate roadways. Straightedge and hard -planing provisions will not apply. Compact the subbase to a minimum of 98% of the maximum density as determined under FM 1-T180, Method D. Priming is not required. When Granular Subbase is substituted for Subgrade on shoulders, achieve a minimum of 95% density of the maximum density as determined under FM 1-T180, Method D.
290-4 Thickness Requirements.
290-4.1 General: Do not substitute granular subbase materials in excess of the tolerance
specified for the asphalt portion of the optional base.
290-4.2 Measurements: When the Department is ready to measure the finished subbase,
provide the coring equipment and the operat or and include this in the unit price for optional base. The Engineer will select the coring locations and make the acceptance measurements. Thickness measurements will be taken through 3 inch diameter holes. For subbase areas greater than 1,000 yd2, the minimum frequency of measurement will be one per 200 feet of roadway. For smaller subbase areas, the minimum frequency of measurement will be one per 500 yd2 of subbase.
290-4.3 Maximum Allowable Thickness: The maximum allowable thickness of the
subbase is 4 1/4 inches. Remove and replace areas of subbase exceeding the maximum allowable thickness.
290-4.4 Minimum Allowable Thickness: The minimum allowable thickness of the
subbase is 3 -1/2 inches. Remove and replace areas not meeting the minimum allowable FY 2023-24 Return to Table of Contents thickness. If authorized by the Engineer, additional asphalt may be substituted to achieve the full combined optional base thickness. FY 2023-24 Return to Table of Contents BITUMINOUS TREATMENTS, SURFACE COURSES , AND CONCRETE PAVEMENT SECTION 300 PRIME AND TACK COATS
300-1 Description.
Apply bituminous prime coats on previously prepared bases and apply bituminous tack coats on previously prepared bases and on existing pavement surfaces.
300-2 Materials.
300-2.1 Prime Coat: For prime coat, use a product listed on the Department’s Approved
Product List (APL), meeting the requirements of 916 -3, or other types and grades of bituminous material if specified in the Contract Documents. A copy of the Bill of Lading representing the material in the distributor tank must be in the truck and be always available. Where prime coats are to be diluted, certify the dilution was done in accordance with the specific dilution r equirements for each product and for each load of material used. The Contractor may select any approved prime coat unless the Contract Documents indicate the use of a specific material. The Engineer may allow types and grades of bituminous material other than those specified above if the Contractor can show the alternate material will properly perform the function of prime coat material.
300-2.2 Cover Material for Prime Coat: Uniformly cover the primed base by a light
application of cover material. The C ontractor may use either sand or screenings for the cover material. For the sand, meet the requirements as specified in 902 -2 or 902-6, and for the screenings, meet the requirements as specified in 902 -5. If the primed base course will be exposed to genera l traffic, apply a cover material coated with 2 to 4% asphalt cement. Apply the asphalt coated material at approximately 10 pounds per square yard. Roll the entire surface of asphalt coated prime material with a traffic roller as required to produce a reas onably dense mat.
300-2.3 Tack Coat: Unless the Contract Documents call for a specific type or grade of
tack coat, use PG 52 -28 meeting the requirements of 916 -2, heated to a temperature from 250 to 300ºF or use an undiluted emulsion listed on the APL, me eting the requirements of 916 -3. Heat the emulsion to the temperature recommended by the tack coat manufacturer. A copy of the Bill of Lading representing the material in the distributor tank must be in the truck and be always available. For night paving , use PG 52-28 tack coat. The Engineer may approve an emulsified tack coat for night paving if the Contractor demonstrates, at the time of use, the emulsion will break and not affect the progress of the paving operation.
300-3 Equipment.
300-3.1 Pressure Distributor: Provide a pressure distributor equipped with pneumatic
tires having a sufficient width of rubber in contact with the road surface to avoid breaking the bond or forming a rut in the surface. Ensure the distance between the centers of openings o f the outside nozzles of the spray bar is equal to the width of the application required, plus or minus two inches. Ensure the outside nozzle at each end of the spray bar has an area of opening greater than the opening of an interior nozzle by 25% to 75%. Ensure all other nozzles have uniform openings. When the application covers less than the full width, the Contractor may allow the FY 2023-24 Return to Table of Contents