Section 407 — Chip Seal
Description
407.01This work consists of applying a single or double course chip seal.
Material
407.02Conform to the following Subsections: Asphalt binder 702.01 Blotter 703.12 Chip seal aggregate 703.09 Emulsified asphalt 702.02
Construction Requirements
407.03Qualifications. A t least 14 days before starting chip seal work , submit a ré sumé for the foreperson describing experience on at least five chip seal projects of similar complexity for approval.
407.04Composition. Submit the following for approval at least 30 days before placement:
(a)Aggregate samples. 80 pounds from the material produced for the project, the gradation range represented, and the proposed target value for each sieve size;
(b)Asphalt sample . 1-gallon sample with test results from the manufacturer according to AASHTO M 316;
(c)Spread rates. The proposed spread rate for the asphalt and aggregate; and
(d)Density. The density of the aggregate according to AASHTO T 19, shoveling procedure.
407.05Equipment. Provide equipment conforming to the following:
(a)Asphalt distributor. Conform to Subsection 406.03. Mainta in two-way radio communication with the aggregate spreader.
(b)Sweeper. Provide two sweepers conforming to Subsection 409.05(d).
(c)Pneumatic -tire rollers.
(1)Three rollers each with a minimum compacting width of 5 feet or two rollers each with a minimum compacting width of 6.5 feet; and
(2)Gross mass adjustable within the range of 200 to 360 pounds per inch of compaction width.
(d)Aggregate spreader. Controls to uniformly deposit aggregate over the full asphalt width.
407.06Surface Preparation. Conform to Subsection 406.04(a) . Prepare the surface as follows:
(a)Newly asphalt patched areas. Fog seal according to Section 406.
(b)Existing asphalt surfaces including recycled asphalt pavements. Dry the surface.
(c)Aggregate base course surfaces.
(1)If using an emulsified asphalt, make the surface damp.
(2)If using an asphalt binder, dry the surface.
407.07Weather Limitations. Apply chip seals only when the following apply:
(a)Ambient air temperature is above 65 °F;
(b)Surface temperature in the shade is above 60 °F;
(c)Surface temperature in the sun is below 150 °F;
(d)Weather is not foggy;
(e)Precipitation or temperatures below 40 °F are not anticipated for at least 24 hours after application;
(f)Sustai ned winds are less than or equal to 10 miles per hour; and
(g)Application is completed at least 2 hours before sunset.
407.08Production Start- Up Procedures.
(a)Preparatory phase meeting. Conduct a pre -chip seal preparatory phase meeting according to Subsection 153.06(a) at least 3 days before the start of chip seal operations .
(b)Control strip. On the first day of each chip seal layer placement, construct up to three 200- to 500-foot control strips that are one -lane wide according to Subsections 407.09 and 407.10. Coordinate the control strip locations with the CO. Start the first control strip at the proposed application rates. Vary the asphalt material or surface aggrega te application rate for each control strip. Construct the control strip using the material, lay -down procedures, and compaction procedures intended for the entire project. Repeat the control strip process until an acceptable control strip is produced. Cease production until the material and the control strip are evaluated and accepted. The CO will indicate which strip will serve as the accepted project control strip. Accepted control strips may remain in place and will be accepted as a part of the completed project. Correct rejected control strips. Use these start -up procedures if changing construction procedures, if resuming production after a termination of production due to unsatisfactory quality according to Subsection 106.04, or the starting of a new construction season.
407.09Asphalt Application. Calibrate asphalt distributors before the start of the project and if directed. Calibrate the spray bar height, check nozzle angle, and verify longitudinal and tr ansverse application rates according to ASTM D2995. Spread building paper on the pavement surface at the start and end of each asphalt application so distributor flow is started and stopped on the paper. Apply asphalt uniformly at the optimum application rate determined from the control strip. Do not apply more asphalt than can immediately be covered with aggregate. Correct skipped areas or deficiencies. Submit documentation of calibrations and application rates at the end of each day’s production. Remove a nd dispose of material spills and associated debris at the end of each shift according to Subsections 203.05 and 203.07.
407.10Aggregate Application. If emulsified asphalt is used, verify the aggregate stockpile moisture daily and use moist surfaced aggregate. If asphalt binder is used, dry the aggregate. Precoat the aggregate uniformly with 2 to 3 percent of residual asphalt by mass of aggregate. Maintain the flow q ualities of the precoated aggregate to allow uniform spreading with the aggregate spreader. Calibrate aggregate spreaders before the start of project if directed. Calibrate the longitudinal and transverse spread rates. Apply aggregate uniformly at the opti mum application rate determined from the accepted control strip. Apply the aggregate immediately after the asphalt material is applied. Operate the aggregate spreader so asphalt is covered with the aggregate before wheels pass over it. For part -width const ruction, leave an uncovered 6-inch- wide asphalt strip to allow an overlap of asphalt material. Cover excess asphalt with blotter. Correct excesses and deficiencies by adding or removing aggregate to achieve a uniform texture before the asphalt cures. Opera te rollers at a maximum speed of 5 miles per hour. Do not allow the aggregate to be displaced by pickup or sticking of material to the tire surface. Roll the surface to bond the aggregate uniformly and thoroughly over the full width. Complete rolling withi n 1 hour after asphalt is applied to the surface. Perform three passes with the rollers. Do not allow traffic to travel over aggregate until rolling is completed and if used, the fog seal has cured. Submit documentation for calibrations and application rates at the end of each day’s production. Use a pilot car according to Section 635 to limit traffic speeds to 10 miles per hour for at least the first 45 minutes after rolling. Limit speeds to 20 miles per hour for the next 24 hours. Vacuum sweep the surface when the air temperature is below 90 °F. Do not displace embedded material. Lightly vacuum sweep the roadway surface within 24 hours of aggregate application. Vacuum sweep the roadway surface within 48 hours after aggregate application to remove excess aggregate from the roadway surface unless otherwise approved. Hand broom in select locations if directed. Dispose of material according to Subsection 203.07.
407.11Placing and Finishing. Apply the asphalt and aggregate according to Subsections 407.09 and 407.10, and Table 407-1. The application rates in these tables are for estimating purposes only. Determine the exact rates based on accepted control strips. Within 7 days of completing the chip seal, apply a fog seal according to Section 406. Tabl e 407-1 Approximate Quantities of Material for Single Course Chip Seal
Type Nominal
Maximum
Size of
Aggregate Aggregate
Gradation(1) Estimated
Quantity of
Aggregate,
pounds per square yard(2) Estimated
Quantity of
Asphalt
Binder, gallons
per square yard Estimated
Quantity of
Emulsified
Asphalt,
gallons per square yard 1A ¾ in A 44 to 53 0.31 to 0.42 0.48 to 0.65 1B ½ in B 29 to 33 0.25 to 0.34 0.39 to 0.53 1C ⅜ in C 24 to 28 0.18 to 0.28 0.27 to 0.43 1D No. 4 D 18 to 24 0.14 to 0.19 0.27 to 0.43
(1)See Table 703 -5 for aggregate gradations.
(2)Ag gregate masses are for aggregates having a bulk specific gravity of 2.65, as determined by AASHTO T 84 and AASHTO T 85. Make proportionate corrections if the aggregate provided has a bulk specific gravity above 2.75 or below 2.55.
407.12Double Course Chip Seal. Apply each asphalt and aggregate layer according to Subsections 407.09 and 407.10, a nd Table 407-2. Table 407-2 application rates are for estimating purposes only. Determine the exact rates based on accepted control strips. If using emulsified asphalt, wait at least 24 hours between appl ications. If using asphalt binder, no wait is required between applications. Lightly vacuum sweep the first layer to remove loose material. Within 7 days of completing the double course chip seal, apply a fog seal according to Section 406. Table 407-2 Approximate Quantities of Material for Double Course Chip Seal
Type
(Thickness) Nominal
Maximum
Size of
Aggregate Aggregate
Gradation(1) Estimated
Quantity of
Aggregate ,
pounds per square yard(2) Estimated
Quantity of
Asphalt
Binder,
gallons per square yard Estimated
Quantity of
Emulsified
Asphalt,
gallons per square yard 2A (⅞ inch) 1st Application ¾ in A 44 to 53 0.29 to 0.41 0.43 to 0.60 2nd Application ⅜ in C 24 to 29 0.41 to 0.46 0.60 to 0.70 2B (¾ inch) 1st Application ½ in B 33 to 44 0.27 to 0.31 0.39 to 0.48 2nd Application ⅜ in C 22 to 26 0.29 to 0.38 0.45 to 0.58 2C (½ inch) 1st Application ⅜ in C 29 to 39 0.17 to 0.27 0.27 to 0.39 2nd Application No. 4 D 13 to 18 0.27 to 0.31 0.39 to 0.48
(1)See Table 703 -5 for aggregate gradations.
(2)Aggregate masses are for aggregates having a bulk specific gravity of 2.65, as determined by AASHTO T 84 and AASHTO T 85. Make proportionate corrections if the aggregate provided has a bulk specific gravity above 2.75 or below 2.55.
407.13Acceptance. See Table 407-3 for sampling, testing, and acceptance requirements. Emulsified asphalt and asphalt binder will be evaluated under Subsections 106.03 and 106.04. Provide a production certification with each load of emulsified asphalt or asphalt binder. Chip seal aggregate gradation will be evaluated under Subsection 106.05. The upper and lower specification limits are equal to the calculated mean of all test results plus or minus the allowable deviations shown in Tables 703-5 and 703-2, except as follows:
(a)If the calculated mean value for a tested sieve exceeds the maximum gradation range value shown in Table 703 -5, then the upper specification is equal to the maximum gradation value in Table 703-5 plus or minus the allowable deviation in Table 703-2.
(b)If the calculated mean value for a tested sieve is less than the minimum gradation range value shown in Table 703-5, then the lower specification is equal to the minimum gradation value in Table 703-5 plus or minus the allowable deviation in Table 703-2. Construction of asphalt chip seals will be evaluated under Subsections 106 .02 and 106.04. Fog seal will be evaluated under Section 406.
Measurement
407.14Measure the Section 407 pay items listed in the bid schedule according to Subsection 109.02 .
Payment
407.15The accepted quantities will be paid at the contract price per unit of measurement for the Section 407 pay items listed in the bid schedule, except the chip seal contract price will be adjusted according to Subsection 106.05. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05. Payment for the chip seal will be made at a price determined by multiplying the contract price by the material pay factor. The material pay factor is the lowest single pay factor determined for each specified sieve of the ag gregate gradation for each aggregate gradation provided. If two gradations are provided for a double chip seal the material pay factor is weighted for the quantity of each aggregate gradation spread as a percent of the total. The material pay factor is calculated as follows: 𝑃𝑃𝑃𝑃 𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 = 𝑃𝑃𝑃𝑃1𝑠𝑠𝑀𝑀 �𝑈𝑈𝑅𝑅1𝑠𝑠𝑀𝑀 𝑈𝑈𝑅𝑅1𝑠𝑠𝑀𝑀 + 𝑈𝑈𝑅𝑅2𝑛𝑛𝑛𝑛 �+ 𝑃𝑃𝑃𝑃2𝑛𝑛𝑛𝑛 �𝑈𝑈𝑅𝑅2𝑛𝑛𝑛𝑛 𝑈𝑈𝑅𝑅1𝑠𝑠𝑀𝑀 + 𝑈𝑈𝑅𝑅2𝑛𝑛𝑛𝑛 � where: PFMaterial = Material pay factor. PF1st = Pay factor for first aggregate gradation. PF1st is the lowest single pay factor determined for each specified sieve. PF2nd = Pay factor for second aggregate gradation. PF 2nd is the lowest single pay factor determined for each specified sieve. SR1st = Spread rate for the first aggregate per square yard. SR2nd = Spread rate for the second aggregate per square yard . Table 407-3 Sampling, Testing, and Acceptance Requirements
Material or
Product
(Subsection) Type of
Acceptance
(Subsection)(3) Characteristic Category Test Methods
Specifications Sampling
Frequency Point of
Sampling Split
Sample Reporting
Time Remarks
Source
Chip seal
aggregate(1) (703.09) Measured & tested for conformance (106.04 & 105) Quality − Subsection
703.091 per material type Source of material Yes Before producing −
Process
control (153.03 ) Gradation − AASHTO T 27 & T 11 2 per day per stockpile Crusher belt (during production) No 24 hours Not required if using a pre- crushed commercial source
Blotter
(703.12) " " − Subsection
703.12" " " " − Asphalt binder(2) (702.01) or emulsified asphalt(2) (702.02 ) Measured & tested for conformance (106.04) Quality − Section 702 1 per material type Point of shipment or delivery Yes(5) Before incorporating into work − Table 407- 3 (continued) Sampling, Testing, and Acceptance Requirements
Material or
Product
(Subsection) Type of
Acceptance
(Subsection)(3) Characteristic Category Test Methods
Specifications Sampling
Frequency Point of
Sampling Split
Sample Reporting
Time Remarks
Production
Chip seal
aggregate(1) (703.09) Statistical(3) (106.05) Gradation (See Table 703-5 for applicable sieves) I AASHTO T 27 & T 11 (3) Production belt or spreader discharge(4) Yes 24 hours −
Process control
(153.03 ) Moisture on surface of aggregates − Visual inspection (407.10) Contractor determined Stockpile or spreader discharge No Before incorporating into work −
Asphalt
binder(2) (702.01) or emulsified asphalt(2) (702.02) Measured & tested for conformance (106.04) Quality − Section 702 1 per tanker truck including trailer Tanker or Distributor Yes(5) − Tested by
Government
Process control
(153.03 ) Placement temperature − − 1 per distributor truck minimum Distributor truck No Before incorporating into work −
(1)Applies to each aggregate grade provided.
(2)Applies to each asphalt material provided.
(3)For plan quantities less than 40,000 square yards, material will be accepted according to Subsection 106.03 . For plan quantities equal to or greater than 40,000 square yards, material will be accepted according to Subsection 106.05 . For plan quantities between 40,000 and 240,000 square yards, the sampling frequency will be determ ined by dividing the plan quantity by eight. If plan quantity exceeds 240,000 square yards, the sampling frequency will be one every 30,000 square yards.
(4)Select one point of sampling . Use the same point of sampling throughout project or lot.
(5)Two 1 -quart samples for asphalt binder. One 1 -gallon sample for emulsified asphalt.