447Asphalt Concrete Mat and Joint Core Density Acceptance

ITEM 447 ASPHALT CONCRETE MAT AND JOINT CORE DENSITY ACCEPTANCE

447.01Description. This specification describes the percent within limits (PWL) acceptance

criteria for asphalt concrete surface courses using mat cores from each day’s production and joint cores from the completed cold longitudinal paving joints. The Department will base acceptance of the compacted mixture in place on the level of d ensity attained separately in the mat and at the cold longitudinal joints as sampled by the Contractor and analyzed by the Department.

447.02Joint Construction. Make a hot longitudinal joint between the mainline pavement lane

and the adjoining shoulder and all ramps and the adjoining shoulders. If a hot longitudinal joint is specified between the mainline pavement lanes, the Contractor may construct a cold longitudinal joint between the mainline pavement lanes and the adjoining shoulders. Cold longitudinal joints will be tested according to 447.05. The Contractor may construct a notched wedge joint for course thicknesses of 1.25 inches (32 mm) or greater. Provide a 0.5 to 0.7 inch (12 to 18 mm) vertical face notch at the upper portion of the wedge after compaction. Allow a notch at the lower wedge toe of height e qual to the nominal maximum aggregate size of the asphalt concrete mixture. Provide a sloped wedge with a width of no more than 6.0 inches (152 mm) and an angle of no more than 10 degrees from horizontal for surface courses up to 1.75 inches (45 mm) lift thickness. Provide a sloped wedge with a width of no more than 10.0 inches (250 mm) and an angle of no more than 15 degrees from horizontal for courses over 1.75 inches (45 mm) lift thickness. The lane width is determined from the upper notch of the wedge. When constructing the wedge joint maintain the asphalt material head the same as or greater than the head of asphalt material in front of the spreading equipment screed. Remove any loose asphalt material at the lower wedge toe or any material that is not part of the wedge slope face before overlaying. When the adjacent lane top portion of the wedge joint is placed over the bottom portion of the first lane wedge joint use the same equipment required for constructing wedge joints at 0 degrees wedge taper to a chieve pre- compaction of the top portion of the wedge joint. Do not place a wedge joint at ramps and other tight areas of slow production as designated by the Engineer. Provide a vertical face joint when not constructing a notched wedge joint. Attach the wedge joint device to the spreading equipment in all wedge joint operations. Ensure the wedge joint device pre -compacts, rather than strikes -off, the asphalt concrete by means of a longitudinal, uniformly decreasing material height of the asphal t concrete forced under the device as the spreading equipment moves forward. Ensure the angle of pre-compaction through the device is 25 to 35 degrees. Ensure the length of travel of material under the device is a minimum of 10 inches (250 mm). Provide additional compaction on the wedge and after the wedge joint device as desired but do not distort the wedge and notch configuration. Ensure the wedge joint device has a variable angle adjustment from 0 degrees (horizontal) to the taper angle necessary to comp lete the wedge height required as well as creating the required notch. Ensure the wedge joint device is constructed to allow at least the same head of asphalt material in front of the device as is in front of the spreading equipment screed. Ensure the wedge joint device does not allow any asphalt material to bypass wedge joint pre - compaction. Do not use wedge joint equipment unless it has been approved by District Testing and meets the above requirements. Seal all cold longitudinal construction joints by coating the cold joint with certified 702.09 Hot Applied Asphaltic Joint Adhesive to provide 100 percent coverage of the joint face, or wedge and notch, and extend at least 1/2 inch (13 mm) on both surfaces.

447.03Core Procedures . Obtain core samples only in the presence of the Engineer and

immediately surrender each core sample to the Engineer for testing. Do not take additional cores 249 beyond what is required in 447.04 and 447.05 unless clearly identified in the approved Contractor ’s QCP. If taken, locate cores for the Contractor’s quality control (QC comparison core) longitudinally from and within 4 inches (100 mm) of the random core. In addition to the QC comparison cores, three extra cores may be taken from the first lot of a JMF for testing to correlate density gauges. Clearly label all cores with mat or joint locations, as applicable, so that they may be readily identified. Any unlabeled cores may be destroyed by the Department. Notify the Department if any questions arise. Do not store additional cores anywhere (on the project, in vehicles, or at the plant) beyond what is required for testing. Test all Contractor cores and maintain records of all tests (core tests and correlated gauge tests) according to the QCP. Destroy all cores immediately after testing is complete. Fill core holes by the next workday with asphalt concrete. Before filling, ensure the holes are dry and tack them with asphalt material conforming to 407.02. Properly compact the asphalt concrete used for filling the hole and leave it flush with the pavement.

447.04Mat Density Acceptance. Obtain ten, 4 inch (100 mm) cores for the Department to test to

determine the in-place density of the compacted mixture as a percentage of the average QC Maximum Specific Gravity (MSG) for the production day the material was placed. If Department MSG VA tests show poor comparison to the average QC MSG according to 403.10 use Department determined MSG results in the density calculation for each production day. Payment for compaction of the completed mainline pavement and ramps is by Lot, based upon the degree to which density is attained. Compact shoulders using the same equipment and procedures as used on the mainline pavement. Payment for shoulders depends on the degree to which the density is obtained on the adjacent mainline pavement lane or ramp. However, when a cold longitudinal joint is made between a mainline pavement lane and an adjoining shoulder, payment for the shoulder will be based on the degree to which the density is obtained on the shoulder. A Mat Density Lot consists of the area of pavement, including shoulders, placed using material produced in one production day as defined in 403.05. If any production day exceeds 3000 tons (2700 metric tons), the Engineer will divide the production day into two lots. If less than 400 tons (400 metric tons) is produced in a production day, then that production day is combined with the next productio n day into a single lot. On the last production day of the project, if greater than 250 tons (250 metric tons) are produced, then the day’s production is a separate lot. If less than 250 tons (250 metric tons) is produced on the last production day for t he project, it is part of the previous lot for acceptance, provided the previous lot was placed within 3 days; otherwise, it is a separate lot. Within 48 hours after the pavement is placed, obtain ten cores for each Mat Density Lot at random locations the Engineer determines. The Engineer will divide a Lot into five equal sublots and calculate two random core locations in each sublot using an acceptable random number selection method. Both mainline pavement and ramps will be included in Lot determinations. The E ngineer will not give the Contractor random core locations early in the Lot placement. The Engineer will tell the Contractor the method used to determine random locations before project start and will use the same method for all Lots. If locations not according to this specification are provided, immediately inform the Engineer. Take the ten random mat cores such that the core's closest edge is at least twelve inches (300 mm) from the cold longitudinal joint, wedge joint upper notch, or vertical face edge. The Department will utilize the PWL calculator located on the Office of Construction Administration’s website to determine the Lot PWL and the Lot pay factors. The PWL calculator uses the computation detailed in Supplement 1044. 250 The lower specification limit (L) is 92.6 percent. No upper limit (U) will be factored into the PWL determination. The Department will determine the pay factor for each Mat Density Lot cored by the pay schedule in Table 447.04-1. The Department will verify the MTD if the MSG determination has a deviation from the MTD of less than or equal to 0.020. If the MTD is not verified, establish a new MTD according to the procedures established in 403.06. If less than 10 cores are available for determining the PWL, OMM will determine disposition of the Lot. The Contractor may dispute the results of the cores following 403.10.G. TABLE 447.04-1 MAT DENSITY LOTS LOT PWL Pay Factor PWL ≥ 98.0 1.04 98.0 > PWL > 50.0 0.55 + (0.005 x PWL) PWL ≤ 50.0 Remove and replace

447.05Joint Density Acceptance. A Joint Density Lot consists of the entire length of eligible

cold longitudinal joint on the project. The Engineer will divide the lot into 2500 foot (760 m) sublots, if the remaining sublot is less than 500 feet (152 m) in length, include that length of l ongitudinal joint in the previous sublot.

incentive/disincentive payment.

project.

(manholes, inlet grates, utilities, bridge structures, etc.)

joint to the other.

and phasing methods do not allow for consistent longitudinal joint construction. Prior to paving, submit requests in writing to the Engineer for consideration of any joints to be excluded on this basis. The Engineer will make the final determination.

longitudinal locations as determined by the Engineer . For vertical joints, center joint density cores on the line where the two adjacent mats abut at the surface. For notched wedge joints, center joint density cores one half the joint taper width, away from the joint line in the direction of the wedge. Obtain joint density cores within 48 hours after the longitudinal joint for each sublot is closed. Clearly label all cores so that locations may be readily identified. Identify the samples by Joint Density Sublot number. 251 Vertical Joint Notched Wedge Joint Figure not to scale Figure not to scale

the mix on each side of the longitudinal joint at each joint density core location according to 447.05. The average of the two values will be used for the density calculation of each sublot sample according to Supplement 1036. Once all test results for the Joint Density Lot have been received, the Department will compute the PWL and average in place density for the lot according to Supplement 1044 using the Excel spreadsheet on the Department’s website. The Department will determine the pay factor for the Joint Density Lot cored by the pay schedule in Table 447.05-1. If all joint cores have a density greater than or equal to 92.0 percent the lot will receive the two percent maximum Joint Density Lot incentive regardless of PWL. TABLE 447.05-1 Joint Density Lots LOT PWL Pay Factor PWL ≥ 90.0 [ (𝑃𝑊𝐿 − 90) 10 × 0.02] + 1 90.0 > PWL > 60.0 1.00 60.0 ≥ PWL ≥ 50.0 1 − [(60 − 𝑃𝑊𝐿) 10 × 0.05] PWL < 50.0 0.95 The Department will calculate a joint density lot pay factor for each item specified with 447 acceptance. The calculated pay factor adjustment will be applied to all material placed under the corresponding line item specifying 447 acceptance. Values computed using equations referenced in this specification may vary slightly from the spreadsheet values due to rounding of numbers. In all cases the numbers computed using the Department’s Excel spreadsheet will govern. All pay factors are shown in number form (not percentages) and are rounded to the hundredth decimal place by the spreadsheet. No other rounding is allowed. The Contractor may dispute the results of the cores following 403.10.G.

447.06Application of Multiple Pay Factors . The Department will apply a mat density pay

factor to each Mat Density Lot as defined in 447.04. The Department will apply one joint core density pay factor to all material placed under the corresponding line item of work specifying 447 acceptance as defined in 447.05. The Department will apply mat and joint core density factor to the contract unit bid price for the corresponding line item of work specifying 447 acceptance. 252