420PERVIOUS ASPHALT PAVEMENT SYSTEM

420.1DESCRIPTION—This work is the construction of plant -mixed asphalt concrete pervious pavement

on a prepared surface designed to allow the infiltration of storm water into the subsoil. The pervious asphalt surface layer is a horizontal plane that is permeable to water and air. The second layer of the storm water system is an open graded, angular stone layer that is used for temporary storm water detention.

420.2MATERIAL—

1.a For use in Asphalt JMF. Coarse Aggregate, Type A, Section 703.2, except Table C gradation does not apply and revise the following quality requirements of Table B.

• Abrasion, Maximum Percent as specified in Bulletin 27, Chapter 2A, Table 6A.

• Thin and Elongated Pieces, Maximum Percent as specified in AASHTO M 323, Table 6, for Flat and Elongated.

• Crushed Fragments, Minimum Percent, as specified in AASHTO M 323, Table 6 , for Fractured Faces, Coarse Aggregate.

1.b For use in Detention Basin. Either AASHTO No. 3 as the primary detention coarse aggregate topped with AASHTO No. 57 as a choker and leveling coarse; or AASHTO No. 57 only, as designed and specified.

2.a For use in Asphalt JMF. Section 703.1, except Table A gradation does not apply and as follows: Determine the un- compacted void content according to AASHTO T 304, Method A, or use the value listed in Bulletin 14, and conform to AASHTO M 323, Table 6. Determine the sand-equivalent value according to AASHTO T 176 and conform to AASHTO M 323, Table 6.

2.b For use in Detention Basin. Fine Aggregate, Type A or Type B.

106.02(a)2.c) when specified and of sufficient strength to resist lateral roller forces where the pervious asphalt

adjoins landscaped areas to provide a clean, durable edge for the pavement. Other edge restraints may be utilized with the approval of the Representative. For manufactured edge restraints, install in accordance with the manufacturer’s guidelines. Provide black edge restraints when permanently incorporated into the project.

in Section 702. Approved polymer additives or ground tire rubber may be used to meet the PG grade.

aggregates as approved 9.5 mm or 19.0 mm dense graded mixtures and with the same PG grade binder where an anti-strip additive was required. If no history exists for an approved dense graded mixture, perform testing in accordance with ASTM D3625 on the finished mix with a minimum of 90% coating to determine moisture susceptibility and an anti-strip additive is required.

the additive and asphalt cement to the mixture. Use the manufacturer’s recommended dosage of the additive, but not less than 0.25% by weight of the asphalt. Select an additive that does not harm the completed asphalt concrete mixture and that is compatible with the aggregate and asphalt supplied for the project.

whether a stabilizer is required. When required, provide cellulose fibers in the mixture according to the tolerances in Table B. Stabilizer dosage rate must be within 0.2% to 0.4% by weight of the total mix.

voids using any method from Table B for bulk specific gravity. Determine the maximum theoretical specific gravity in accordance with AASHTO T 209. Gyrate two specimens in accordance with AASHTO T 312 and determine bulk specific gravity by averaging them, employing one of the methods in Table B to calculate air voids. Test materials, proportions, and the mixture at the asphalt concrete plant laboratory. Verify conformance with the uniformity requirements of this specification. Verification testing may be performed by the LTS at the Department’s discretion. Provide a JMF that conforms to all Department requirements. Submit a copy of the JMF to the DME/DMM at least 3 weeks before the scheduled start of producing the mixture for the project. If the Department has not used the JMF on a previous project, provide test results from previous mixture production that indicate the mixture conformed to all JMF production tolerances when submitting the design for initial review.

TABLE A Composition of Mixture (Total Percent by Mass (Weight) Passing Square Openings Based on Laboratory Sieve Tests) Pervious 9.5 mm Wearing Pervious 19.0 mm Binder Sieve Size Percent Passing Percent passing 25.0 mm (1-inch) 100 19.0 mm (3/4-inch) 100 85 - 100 12.5 mm (1/2-inch) 95 - 100 35 - 68 9.5 mm (3/8-inch) 70 - 100 4.75 mm (No. 4) 20 - 40 10 - 25 2.36 mm (No. 8) 10 - 20 5 - 15 75 µm (No. 200) 0 - 4 0 - 4

Asphalt Content 5.5% - 7.0% 3.0% - 5.0%

TABLE B Mixture Composition

Gyrations Ninitial N/A Ndesign 50 Nmaximum N/A

Air Voids ASTM D6752 16.0% - 20.0% AASHTO T 275 18.0% - 22.0% AASHTO T 269* 18.0% - 22.0% Draindown AASHTO T 305 ≤ 0.3% *When using AASHTO T 269 the height of the specimen will be determined by the gyratory compactor reading at Ndesign.

Representative at the start of the project. Do not begin production until receiving approval of the QC Plan from the Representative.

TABLE C Production Testing Property Frequency Range Asphalt content Daily ± 0.7% Gradation Daily Table A Air Voids Daily Table B Draindown Daily ≤ 0.3% at design compaction temperature

results of QC tests for asphalt content, gradation, and air voids. Provide copies of the certifications to the Inspector-in-Charge within 1 working day after performing QC tests.

420.3CONSTRUCTION—

operations to be used in production and construct at the project site on a prepared subgrade and base, using the material and construction requirements used in production. Each section must have an area of at least 225 square feet. Perform infiltration on both test sections in accordance with ASTM C1701. The average of both infiltration values must exceed 200 inches per hour. Compacted thickness cannot be more than 1/4-inch less than the design thickness.

subgrade to be left as permeable as possible. Where erosion of subgrade has caused accumulation of fine materials and/or surface ponding, remove the accumulated material using light equipment and scarify the underlying soil to a minimum depth of 6 inches using a spring tooth rake or equivalent and a light tractor. Avoid driving haul trucks or other heavy equipment through the installation area. Repair damaged areas to the satisfaction of the Representative. Do not compact or otherwise subject the existing subgrade under pavement areas to excessive construction equipment traffic before geotextile and stone bed placement. Satisfactorily correct and repair any damaged or compacted areas to the satisfaction of the Representative. Notify the Representative upon completion of subgrade work for final inspection and acceptance before proceeding with basin and choker course installation.

bottom of the detention base with a minimum of 2 inches of fine aggregate to prevent soils from migrating into the storm water storage area. Wrap basin sides with a non- woven geotextile fabric. Install detention basin coarse aggregate in 8- inch maximum lifts. Compact the course in as specified in Section 360.3. Install aggregates to grades indicated on drawings. Place the specified depth(s) of coarse aggregate on top of the fine aggregate and roll as specified in Section 420.3(f). Remove temporary sediment control materials when the site is fully stabilized.

is lower than 50F.

not use pneumatic tire rollers.

binder course. If practical, do not allow traffic on the binder course to prevent contamination. Remove and replace binder course that cannot be cleaned to the Representative’s satisfaction. Coat existing vertical surfaces of curbs, structures, gutters, and pavements that will be in contact with asphalt mixtures with a thin, uniform coating of emulsified asphalt (AASHTO SS-1, CSS-1, SS-1h, CSS-1h, or TACK) applied in two or more applications, or of the class and type designated for the asphalt course. Do not use a tack coat between lifts of any p ervious asphalt. Place t he wearing course as soon as practical after the placement of the binder course.

spreader. Spread or strike off the entire for the entire lane width or as much lane as practical. Place the mixture in maximum 4- inch compacted lifts. Adjust screed assemblies to provide the cross section and depth indicated. Construct the profile to the design grade line. Use fully automatic sensors to control profile and transverse grade. A llow the mixture to cool to 100F before placing subsequent layers or pavement courses. Perform handwork at locations directed by the Representative. For mult iple lift construction, second lift may be placed and rolled perpendicular to the direction of placement and rolling of the first lift. Do not use pervious pavement beds for storage of equipment, materials, or soils during construction.

10-ton steel-wheeled static roller or vibratory roller operated in the static mode. Limit compaction to not more than four passes to preclude a reduction in the surface porosity. One roller pass is defined as one trip of the roller in one direction over any one spot. Do not over compact the material to the point that it is not free draining, or the aggregate is crushed.

placed by 1 inch to 2 inches. Maintain the uniform un- compacted depth adjacent to a compacted lane necessary to provide a smooth joint after compaction.

occurs in pe rvious paving operations, install a temporary vertical bulkhead to form a straight transverse construction joint. The joint must be the full depth and width of the pervious paving course. Instead of a temporary bulkhead, a full depth transverse joint may be sawed before resuming paving.

and at transverse joints and paving notches. Test the surface in stages using a 12 -foot straightedge. At each stage, hold the straightedge in contact with the surface and parallel to the road centerline and, in successive positions, test the pavement surface from one side to the other. Advance the test location to the next stage by moving the straightedge along the pavement centerline by not more than 5 feet. Immediately correct irregularities of more than 3/8-inch by loosening surface mixture and removing or adding p ervious paving course. For irregularities exceeding 3/8- inch that develop after compaction is completed, correct the irregularity by a method that does not produce contaminating fines or damage the base. Do not grind or mill the pervious paving course. The area is defective if irregularities or defects remain after final compaction. Remove and replace defective areas. If allowed , submit a correc tive action plan to the representative for approval.

to the full depth of the pervious course for each 3,000 square yards or less of completed base course. The Representative may require additional test holes in areas the Representative suspects are deficient in depth. The Representative will measure the depth of the pervious course. Using material acceptable to the Representative, backfill the test holes and compact the material to fill the test hole flush with the completed course. Remove and replace sections deficient in depth by 1/2- inch or more. Start correction at the point of determined deficiency and continue correction longitudinally and transversely until the depth is within 1/2-inch of the indicated depth.

for every 10,000 square feet of pervious asphalt pavement placed in accordance with ASTM C1701. Remove and replace pervious asphalt pavement not meeting or exceeding a minimum average infiltration rate of 200 inches per hour. Document the average infiltration value from testing for use in future maintenance activities.

pervious asphalt that is deficient in surface tolerance, depth, asphalt content, percent of coated aggregate particles is less than 95%, or when percent passing the 4% maximum for the No. 200 sieve for the composite mixture is exceeded. Pervious courses are also considered defective if the ASTM C1701 infiltration rate is less than 200 inches per hour. With written permission from the District Executive, low areas may be filled during construction of the next pavement course.

420.4MEASUREMENT AND PAYMENT—