360ASPHALT TREATED PERMEABLE BASE COURSE

360.1DESCRIPTION—This work is the construction of an asphalt treated permeable base course (ATPBC)

on a prepared surface. When placed on subgrade, it includes the preparation of subgrade as specified in Section 210.

360.2MATERIAL—

crushed particles with at least three faces resulting from fracture.

stripping potential. Furnish hydrated lime conforming to ASTM C1097 and add the lime as follows:

• Add at least 1% hydrated lime by weight of the total dry aggregate.

• Provide a separate bin or tank and feeder system to store and accurately proportion the lime, in dry form, into the aggregate.

• Provide a convenient and accurate means of calibrating the proportioning device.

• Interlock the proportioning device with the aggregate feed or weight system.

• Mix the lime and aggregate to uniformly coat the aggregate with lime.

• Furnish aggregate containing at least 3% free moisture.

• Do not stockpile lime treated aggregate.

• Control the feeder system by a proportioning device accurate to within 10% of the specified amount.

• Provide a flow indicator or sensor and interlock with the plant controls such that production is interrupted if there is a stoppage of the lime feed.

• Before production, obtain approval of the method to introduce and mix the lime and aggregate.

than hydrated lime. Blend the additive with the asphalt cement before adding 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.

test requirements do not apply. Design a JMF with an initial target asphalt content of 2.5% by weight. If

necessary, adjust the asphalt content within the range specified in Table A below to uniformly coat the aggregate and ensure the aggregate has no observable runoff of excess asphalt. Test materials, proportions, and the mixture at the asphalt concrete plant laboratory. Verify conformance with the uniformity requirements specified in this Section. When required, the Department will perform the tests at the LTS. 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 previous projects, provide test results from previous mixture production that show the mixture conformed to all JMF production tolerances.

and at least annually thereafter. Do not start ATPBC production until after the Representative reviews the QC Plan.

tests to verify the mixture conforms to the JMF. After the first day, perform tests for asphalt content and aggregate gradation according to the QC Plan and PTM No. 1. Produce ATPBC conforming to the gradation requirements in Table A and with a asphalt content within 0.8% of the JMF (n=1). Ensure the aggregate is uniformly coated with asphalt and no runoff of excess asphalt is observed.

results of QC tests for asphalt content and gradation. Provide the certification to the Inspector -in-Charge within 1 working day after taking QC tests.

TABLE A Composition of Mixture (Total Percent by Mass (Weight) Passing Square Openings Based on Laboratory Sieve Tests) Sieve Size Percent Passing 37.5 mm (1 1/2-inch) 100 25.0 mm (1-inch) 95 – 100 12.5 mm (1/2-inch) 35 - 65 4.75 mm (No. 4) 12 – 24 1.18 mm (No. 16) 6 - 16 75 µm (No. 200) 0 – 5

Asphalt Content 2.0% - 3.0%* * For approved gravel and slag mixtures, the Representative may allow the Contractor to exceed the upper limit.

360.3CONSTRUCTION—Section 413.3, with modifications as follows:

Do not place ATPBC on surfaces that are unstable, frozen, or below a temperature of 35F. Do not place ATPBC when the air temperature is below 35F or during rain. If work is halted because of weather conditions, the Representative may allow the Contractor to place limited quantities of ATPBC that are enroute to the project.

the design and control test.

material so that combining with aggregate produces a completed mixture. Coat the aggregate with the asphalt material to form a film of adequate thickness to provide the required binding properties. Produce ATPBC at a temperature below 320F that also provides suitable viscosity for adequate coating of aggregate particles, and that does not cause segregation of asphalt and aggregate during transportation. Do not stockpile ATPBC. The ATPBC must be placed within 8 hours from when it is made.

Use steel-wheel power rollers with a manufacturer’s certified metal weight of 8 tons to 10 tons.

Use a slip form paver, as specified in Section 413.3(e), or a mechanical spreader. Spread and strike off the mixture 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 automated sensors to control profile and transverse grade. Allow the mixture to cool to 100F before placing subsequent layers or pavement courses. Perform handwork at locations directed by the Representative.

Perform rolling as soon as the mat has cooled sufficiently to avoid shoving or lateral movement of the ATPBC. Seat ATPBC using a n 8-ton to 10- ton, steel -wheeled roller, or vibratory roller operated in the static mode only. Compact ATPBC by applying four roller passes. One roller pass is defined as one trip of the roller in one direction over any one spot. Additional passes are allowed only to eliminate any surface irregularities, or creases. Do not c ompact 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 uncompacted depth adjacent to a compacted lane necessary to provide a smooth joint after compaction.

interruption occurs in ATPBC 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 ATPBC. Instead of a temporary bulkhead, the Contractor may saw construction joints.

Test the finished surface at locations the Representative suspects are irregular and at transverse joints and paving notches. Test the surface in stages using a 10- 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. Correct irregularities of more than 1/2 inch by loosening surface mixture and removing or adding ATPBC. For irregularities 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 ATPBC. The area is defective if irregularities or defects remain after final compaction.

Carefully dig or drill one 6- inch diameter test hole to the full depth of the ATPBC 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 base course. Using material acceptable to the Representative, backfill the test holes and compact the material to fill the test hole flush with the completed base 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.

Section 105.13 and as follows: Traffic is not allowed on the asphalt treated permeable base material, except for trucks and equipment required to place the next layer. Replace areas damaged or contaminated, as directed and at no cost to the Department. If necessary, re-compact the ATPBC before starting subsequent paving. Protect the surface from damage before and during the concrete paving process.

Unless otherwise directed in writing by the District Executive, remove and replace ATPBC deficient in surface tolerance, deficient in depth, defective in asphalt content, or excessive in percent passing the 75 µm (No. 200 sieve). The ATPBC is defective in asphalt content if production tolerances are exceeded, percent of coated aggregate particles is less than 95%, or the mixture contains observable runoff of excess asphalt. With written permission from the District Executive, the Contractor may fill low areas during construction of the next pavement course. Acceptance testing and QA testing does not relieve the Contractor of responsibility for defective material or work.

360.4MEASUREMENT AND PAYMENT—Square Yard or Ton

FLEXIBLE PAVEMENTS