Item 422  CHIP SEAL

422.01  Description

422.02  Materials

422.03  Equipment

422.04  Weather Limitations

422.05  Test Strip

422.06  Surface Preparation

422.07  Binder Application

422.08  Cover Aggregate Application

422.09  Construction Operation

422.10  Quality Control

422.11  Acceptance

422.12  Method of Measurement

422.13  Basis of Payment


422.01  Description.  This work consists of preparing and applying a single or double chip seal.

422.02  Materials.  Use an RS-2 emulsified binder conforming to 702.04 for projects with an ADT less than 500. Use polymer emulsified binder conforming to 702.16 Type A for projects with an ADT greater than 500.  When a project has multiple pavements with ADTs above and below 500 use the polymer emulsified binder, 702.16.A.

Provide cover aggregate for the chip seal Job Mix Formula (JMF) of washed limestone or dolomite conforming to 703.05.  Do not use an aggregate source designated with “SR” on the Aggregate Source Group list in accordance with 703.01.F.  Additionally the following requirements apply:

Stockpile the material to be used for the chip seal at the aggregate source. 

Obtain five (5) samples from the stockpile and perform gradation testing on each sample and determine the percent passing for each sieve size listed in Table 422.02-1

A.      Calculate the total range for the No. 8 (2.36 mm) sieve for all five samples.  The range will not exceed 6%.

B.      Calculate the percent passing the No. 200 (75 µm) sieve for each sample.  No single sample value will exceed 2.0 percent.

C       Calculate the average of each sieve for all five samples.  Assure the average value for each sieve is within the requirements of Table 422.02-1.

Submit a letter to the Engineer and DET containing the Job Mix Formula (JMF) gradations and the calculations to show the cover aggregate meets requirements.

If a staging location will be used for the chip seal aggregate first move the initially tested aggregates from the aggregate source stockpile to the staging location and construct a staging stockpile.  Then obtain five (5) aggregate samples from the staging location stockpile and perform gradation testing on each sample to determine the percent passing for each sieve size listed in Table 422.02-1.

Evaluate the staging location aggregate samples the same as the aggregate source samples except allow an average for the No. 200 (75 µm) sieve not greater than 1.7 percent.

Submit the Job Mix Formula (JMF) gradations from the staged stockpile and the calculations to show the cover aggregate meets requirements in letter form to the Engineer and DET.

If the chip seal aggregates fail to meet requirements, either at the aggregate source or the staging location, re-wash and/or rework the aggregate materials and retest the new stockpiles.

TABLE 422.02-1

Sieve Size

Total Percent Passing

1/2 inch

(12.5 mm)


3/8 inch

(9.5 mm)

85 to 100

No. 4

(4.75 mm)

5 to 25

No. 8

(2.36 mm)

0 to 10

No. 16

(1.18 mm)

0 to 5

No. 200

(75 µm)

0 to 1.5 [1]

[1]  Washed gradation value


The District may obtain and test validation samples of the JMF aggregates at any time. If a single validation sample is either outside the values in Table 422.02-1 with the exception that  the No. 200 (75 µm) value is not greater than 2.0 percent, the district will obtain five (5) samples and retest to determine if the aggregate JMF falls within the limits of Table 422.02-1.  If the JMF verification test doesn’t meet the source or staging location limits the stockpile is not acceptable.

422.03  Equipment.  Provide equipment conforming to the requirements of this section.  Obtain approval of equipment before starting the job.

Use equipment for binder distribution conforming to 407.03, except ensure that it has a computerized rate control that automatically adjusts the binder pump to the unit ground speed and has a gauge or meter in plain view for reading gallons (liters).  Use appropriate spray nozzles for the material and rate specified.

Use Type II pneumatic tire rollers conforming to 401.13, except the maximum capacity shall not apply.

Use self-propelled aggregate spreaders with a variable width aggregate hopper capable of placing from 8 to 16 feet (2.4 to 4.8 m) in any increment and a computerized rate control that automatically adjusts the aggregate output to the unit ground speed.  Equip spreaders with pneumatic tires, a screen to remove oversized material, revolving cylinders, and adjustments necessary to produce a uniform distribution of particles at the specified rate.

Use power sweepers or rotary brooms in initial surface preparation and for removing loose particles.  Use pickup type sweepers in areas where the aggregate shoulder does not exist.  Do not sweep loose aggregate onto lawns, curbed areas, or intersections.

Furnish accurate thermometers for determining any of the applicable temperature requirements of this specification.

422.04  Weather Limitations.  Place the chip seal when the pavement and atmospheric temperature is 60 °F (16 °C) or above and the atmospheric temperature is 70 °F (24 °C) or above.  Do not schedule the performance of this work for the time period before May 1 or after September 1.  Do not place chip seal if any of the following conditions exist:

A.      Impending weather conditions do not allow for proper curing or if temperatures are forecasted below 50 °F (10 °C) within 24 hours from the time of work.

B.      The existing pavement temperature is 140 °F (60 °C) or above.

422.05  Test Strip.  Construct a continuous 1000-foot (300 m) long by lane width test strip. Do not waive test strips regardless if the same materials have been used on another project.

Determine the initial binder application rates and aggregate application rates for the test strip.

For a single chip seal, an initial target rate of 0.37 ±0.03 gallon per square yard (1.68 L/m˛) is recommended for the test strip.  For double chip seal, a target rate of 0.36 ±0.03 gallon per square yard (1.54 L/m˛) for the first course and 0.33 ±0.05 gallon per square yard (1.68 L/m˛) for the second course is recommended for the test strip.  Notify the Engineer of the initial target rates.

Calibrate the aggregate spreader and verify the application rates with a one square yard (one square meter) piece of cardboard or other material to collect and weigh the aggregate. Do not over apply cover aggregate relying on vacuum and broom sweeping to pick up all excess. Amounts of loose aggregate that create a nuisance to the public will result in work stoppage. If work is stopped by the Engineer recalibrate the aggregate spreader determining a new application rate and apply cover aggregate at the new rate.  Verify the aggregate gradation during the test strip and give results to the Engineer.

The Engineer and Contractor will review the test strip the next workday for streaking, ridging, bleeding, aggregate loss or other problems. If the review shows the test strip meets the requirements of 422.11 and the application rate and quality control tests show all is in control compared to the JMF, then progress with the work. Should problems be noted, the Engineer may require another test strip.

422.06  Surface Preparation.  Clean the pavement according to 407.05.  If necessary, clean areas of the pavement with a hand broom. 

Remove all existing pavement markings 740.03 (polyester), 740.04 (thermoplastic) and 740.07 (epoxy) using an abrasion method conforming to 641.10

For a single chip seal either remove and replace any existing raised pavement markers or protect the existing raised pavement markers from the single chip application process.

For a double chip seal application remove the raised pavement markers according to 621.08.

Do not place material until the Engineer approves the surface.

422.07  Binder Application.  Before applying binder, ensure that sufficient cover aggregate is available for immediate application.  Apply the binder at the target rate(s) established during the test strip. 

Maintain the binder temperature from 150 to 185 °F (65 to 85 °C) during construction, including the start of each day.  Reheat the binder at a rate of no more than 25 °F (14 °C) per hour, when the binder is allowed to cool below 150 °F (65 °C).

If the target application rates are not the optimum application rates to achieve proper stone embedment during the actual application, immediately notify the Engineer. Proper stone embedment is typically 1/2 to 2/3 of the stone chip height and can be checked by pulling out several chips by hand. Adjust and document the new application rate by stationing.   Recheck stone embedment after adjustment and obtain the Engineer’s approval of the new rate.

Do not allow the binder to streak on the road surface.  If the Engineer determines that streaking is occurring, cease operations until the Engineer is satisfied that streaking has been eliminated.

At the beginning and at the end of a contract section, start and stop the application on a removable protective cover (paper, metal sheets, or other suitable material) sufficiently wide enough to allow full application on the surface being treated.  Make transverse and longitudinal laps in such manner to ensure that the texture of the finished surface is uniform and continuous.  To prevent lapping at transverse junctions, promptly shut off the binder spray at the end of the application.  Before continuing the application, place a removable protective cover a sufficient distance back from the joint on the cover aggregate so the sprayers are operating at full force when the distributor has attained the predetermined speed upon reaching the uncovered surface.  Upon completion, remove all removable protective covers.

422.08  Cover Aggregate Application.  Verify the application rate with a one square yard (one square meter) piece of cardboard or other material to collect and weigh the aggregate before placing binder.  Adjust if necessary and re-verify.  Record final results and inform the Engineer. Immediately after applying the binder, apply cover aggregate uniformly without ridges or laps at the specified rate adjusted as directed by the Engineer to produce a minimum of excess loose particles.  Spread the material in such manner that the tires of the truck or aggregate spreader at no time contact the uncovered and newly applied binder.  Before rolling, correct deficiencies in the application of cover aggregate in a manner satisfactory to the Engineer.

After rolling, protect the surface from traffic damage during the period required for the binder to cure sufficiently and prevent dislodging of the aggregate particles by normal traffic.  During this period and as directed by the Engineer, correct deficiencies in cover aggregate by spreading additional aggregate or by light brooming.

Apply cover aggregate at a rate necessary to provide full coverage of the binder and to avoid tracking. Do not over apply cover aggregate relying on vacuum and broom sweeping to pick up all excess.  Nuisance to the public amounts of aggregate will result in work stoppage.  If work is stopped by the Engineer recalibrate the aggregate spreader determining a new application rate and apply cover aggregate at the new rate. If the target rate needs adjustment due to the gradation of the aggregate or due to existing surface conditions of the pavement, immediately notify the Engineer and document the new rate by stationing.

422.09  Construction Operation.  Establish stations at 1000-foot (300 m) intervals on the entire project before placing materials.  Clearly identify and maintain the stations until project completion.

Keep the binder distributor, aggregate spreader, and rollers as close to each other as possible.  Do not allow the binder distributor to be more than 150 feet (45 m) ahead of the aggregate spreader.

Perform rolling immediately after placing the aggregate, but before the binder sets up.  Do not leave aggregate unrolled for more than 5 minutes.  Perform a minimum of two complete roller passes over the aggregate.  A single complete pass is forward and backward over the same path.  For each new pass, overlap the previous pass by about one-half the width of the roller.  Use a minimum of three rollers, and roll in a longitudinal direction at a speed not greater than 5 miles per hour (8 km/h).  Do not operate rollers at speeds that cause pick-up or dislodging of aggregate particles.

After the binder sets, and before placing a second course for double chip seals, and within 4 hours, sweep the pavement using a power broom or pickup sweeper as needed to remove all loose aggregate. If the pavement cannot be swept within the 4-hour period due to problems associated with the stone moisture, binder, breaking, humidity, or other unknown, the Engineer may suspend the operation until the problem is resolved or more suitable conditions are obtained to maintain the 4-hour time frame for sweeping. Extend sweeping 1 foot (0.3 m) beyond the edge of the pavement to help prevent migration of loose aggregate back onto the pavement.  Do not re-use aggregate from a chip seal that is swept from the pavement or that is already loose off the pavement edge. 

The Contractor is responsible for claims of damage to vehicles until the pavement and shoulders receive a final sweeping immediately before application of permanent pavement markings or a fog seal, if a fog seal is required.

Wait at least 24 hours before placing the second course of a double chip seal.  Ensure that the first course meets requirements of this specification and is cured, swept and capable of withstanding construction traffic without damage. 

Correct damage to the underlying chip seal before placing the final chip seal.

Place the longitudinal construction joint on a lane line or as directed by the Engineer.  For double chip seal, place the longitudinal construction joint for the first course 6 inches (150 mm) off the centerline and place the second course so the longitudinal joint is at the centerline.

Before opening to traffic, post the roadway with “Loose Stone” signs and a “35 mph” speed plaque mounted below the sign.  Ensure that signs conform to Item 614.  Place these signs at a maximum of 0.5-mile (0.8 km) intervals.  Remove the signs as directed by the Engineer.

On two-lane roads or pavements where traffic is maintained on a chip seal constructed that workday, provide a traffic control pilot vehicle operated at no more than 25 miles per hour (40 km/h) in the immediate work area.

Protect all utility castings, monument boxes, and other similar items using tarpaper or other approved material.  Remove protection before sweeping and opening to traffic.

422.10  Quality Control

A.      General.  Use the methods described in this section to measure compliance.  If test results exceed any of the identified quality control tolerances, stop placement and immediately notify the Engineer and DET.  Identify the cause of exceeding any of the identified quality control tolerances and document in detail the corrective action necessary to bring the deficiency into compliance.  Obtain the Engineer’s approval before resuming work.  Upon resuming work, take another sample and immediately provide the test results to the Engineer.  If the tolerances are exceeded, stop the work.  Do not resume work until approved by the Engineer and DET.  The Department can obtain samples of materials at any time. Aggregate samples can be taken from sources, on-hand stockpiles or the aggregate spreader box.  Work can be stopped and materials can be rejected on the basis of poor Department test results.

B.      Binder.  Within one hour of start of production obtain and label a binder sample from the distributor truck and give the sample to the Engineer the same day.  Provide and sample the binder in one quart plastic containers with plastic screw tops.  Take more samples when requested by the Engineer.  

For the binder application rate, as determined by a yield check, do not exceed a tolerance of ±0.02 gallon per square yard (0.09 L/m˛) from the established application rate.

C.      Coarse Aggregate.  At a minimum test one sample taken from the aggregate spreader box at production start and sample and test one sample from the aggregate spreader box randomly during the day.  An aggregate spreader box sample may be taken by laying a piece of suitable material under the spreader as it moves forward.  Include additional testing when directed to sample and test by the Engineer.  Sample and test aggregate according to AASHTO T 2, AASHTO T 248, and Supplement 1004 (AASHTO T 11 where required).  Use washed gradations for determining the No. 200 (75 µm) sieve.  The Contractor may use additional tests.  These may include dry gradations for control purposes but acceptance of on-hand aggregate will be based on washed gradations only.  Reject and do not use aggregate creating dusting nuisance to the public on the project. 

Reject truckloads of aggregate if water is seen coming from the truck bed.

Reject aggregate that does not meet the following requirements:

No. 4 (4.75 mm) sieve from JMF


No. 8 (2.36 mm) sieve from JMF


No. 200 (75 µm) sieve from JMF

±1.0%, 2.05% upper limit

Aggregate moisture content

(by dry weight)

4.0% max. for aggregates with an Absorption > 2.0%,

3.0% max. for aggregates with an Absorption ≤ 2.0%


D.      Documentation.  Provide the Engineer a daily report with the following:

1.      Control section, project number, county, route, and Engineer.

2.      Date, air temperature, pavement temperature, and humidity.

3.      Binder temperature.

4.      Beginning and ending stations.

5.      Yield checks on binder (three per day, minimum).

6.      Yield checks on aggregate (three per day, minimum).

7.      Gradation, moisture content, and station (One sample from spreader box at production start, one random sample during the day and any other samples when directed by the Engineer).

8.      Length, width, and total area.

9.      Condition of “Loose Stone” signs with “35 mph” speed plaques.

10.    Contractor representative’s signature.

Provide a bill of lading for binder and aggregate as requested or at project completion.

422.11  Acceptance.  During the application of the chip seal, inspect the chip seal for deficiencies resulting from poor workmanship, flushing, tracking from equipment, surface patterns, loss of stone, and sweeping.  Inspect workmanship for untreated areas, minimum overlap on longitudinal joints, and minimum overlap on construction joints.

Verify the following for daily acceptance:

A.      Finished surface has no more than four tears or untreated areas greater than 1 inch (25 mm) wide and 4 inches (100 mm) long in any 120-square yard (100 m2) area.

B.      Joints appear neat and uniform without buildup, uncovered areas, or unsightly appearance.

C.      Longitudinal joints have less than a 2-inch (50 mm) overlap on the adjacent passes.

D.      Transverse joints have no more than 1/4-inch (6 mm) difference in elevation across the joint as measured with a 6-foot (2 m) straightedge.

E.      Chip seal edge is neat and uniform along the roadway lane, shoulder, and curb lines.

F.      Chip seal edge has no more than 2-inch (50 mm) variance in any 100 feet (30 m), along the roadway edge or shoulder.

G.      Typical stone chip embedment is 1/2 to 2/3 of typical stone chip height.

For project acceptance, the Contractor and Engineer will review the completed work 25 to 35 days after placement.  The finished work must meet the following requirements:


Defect [1]


Surface patterns

Alternate lean and heavy lines

(Ridges or streaking over the surface)


Distinctive appearance

(Excess binder on surface)

Loss of cover aggregate

Patches or lines of aggregate lost from surface


[1]  No more than 20% of any 120 square yard area can contain any defect.  The measurement of the 120 square yard area begins at the start of the defect.

Perform all corrective work to the satisfaction the Engineer.

422.12  Method of Measurement.  The Department will measure Single Chip Seal Course or Double Chip Seal Course by the number of square yards (square meters), completed and accepted in place.  The Department will determine the width by measuring the actual width of the chip seal.  The Department will determine the length along the centerline of each roadway or ramp.

The Department will measure the number of raised pavement markers removed if a Double Chip Seal is specified.

422.13  Basis of Payment.  The Department will not pay for materials, equipment, or labor to make corrections.

The cost of removal of all existing pavement markings according to 422.06 is incidental to this item.

The cost of any removal or protection of existing raised pavement markers on a single chip seal according to 422.06 is incidental to this item.

The Department will pay for removal of existing raised pavement markers on a Double Chip Seal application according to Item 621 Raised Pavement Markers Removed

The Department will pay for accepted quantities at the contract prices as follows:

Item           Unit                                Description

422            Square Yard                 Single Chip Seal

                       (Square Meter)         

422            Square Yard                 Double Chip Seal

                       (Square Meter)