2307.01 DESCRIPTION.
Bituminous seal coat (BSC) shall consist of one or more applications of binder bitumen with one or more successive applications of cover aggregate.

On Primary Road projects where limestone or crushed gravel cover aggregate is used, dust control shall be required by applying diluted asphalt emulsion to the completed BSC surface. On non-Primary Road projects, dust control shall be as specified in the contract documents.

2307.02 MATERIALS.
Materials shall meet the following requirements:

A. Aggregates.
Cover aggregate shall meet requirements of Section 4125 for the size designated. Unless otherwise designated, sand shall be used for shoulders and winter seals, and the 1/2 inch (12.5 mm) size crushed aggregate shall be used for other work. On Primary projects, when 1/2 inch (12.5 mm) size cover aggregate is specified, use of crushed stone or crushed gravel will be required.

For each contract, each load of each size of aggregate, shall be similar in type and gradation. A change in source shall be made only with approval of the Engineer.

For Primary projects, the aggregate size designated in the contract shall be furnished. The 1/2 inch (12.5 mm) size shall not be used when the 3/8 inch (9.5 mm) size is designated.

B. Bituminous Material.
Bituminous material shall meet the requirements of Section 4140 or 4138.

1. Emulsified Asphalt.
Unless otherwise specified in the contract documents, the binder bitumen shall meet the requirements for CRS-2P as specified in Section 4140.

2. Cut Back Asphalt.
Cut back asphalt shall be furnished with an approved anti-stripping additive as described in Article 4138.01.

3. Asphalt Emulsion for Dust Control.
Asphalt Emulsion for Dust Control shall be grade CSS-1, CSS-1H, or SS-1H as specified in Section 4140. This emulsion shall be diluted with water prior to application. The initial dilution rate shall be seven parts water to one part emulsion.

2307.03 EQUIPMENT.
Equipment shall meet requirements of Section 2001 and the following:

A. Aggregate Spreaders.
Article 2001.13, B, shall apply except that, when provided in the contract documents, an aggregate spreader meeting requirements of Article 2001.13, A, may be used.

Aggregate spreaders described in Article 2001.13, B, shall be equipped with a scalper or segregator screen, provided by the spreader manufacturer, mounted below the feeder roll. The size of the openings in the scalper screen shall be as recommended by the spreader manufacturer, and when adjusted to the proper angle, the coarse fraction of the aggregate will be placed on the binder bitumen first and the fine fraction will be dropped through the screen on top of the larger particles. The screen angle shall be adjusted as necessary on the project. Use of this screen is required.

B. Equipment for Distributing Bitumen.
Article 2001.12 shall apply.

When emulsion binder bitumen is used, the distributor spray bar shall be equipped with nozzles, furnished by the distributor manufacturer, which are specifically designed to apply emulsion. Before the work is started, the Contractor shall furnish the Engineer a written statement indicating the size or part number of the nozzles recommended, and certifying that these nozzles are installed on the distributor.

C. Brooms.
Article 2001.14 shall apply.

Power brooms used to remove loose aggregate from newly seal coated surfaces shall be capable of exerting uniform down pressure, for the full width of the broom and without vibration or bounce, sufficient to remove loose aggregate without dislodging particles which are stuck in the binder bitumen.

D. Heating Equipment.
Article 2001.11 shall apply.

E. Rollers.
Self propelled, pneumatic tired rollers, meeting requirements of Article 2001.05, C, shall be used to embed the cover aggregate. One pneumatic tired roller will be required for work involving sand cover aggregate, and a minimum of two pneumatic tired rollers will be required for work involving other cover aggregate.

F. Weighing Equipment.
Article 2001.07 shall apply.

2307.04 CONSTRUCTION.
The rates of application for binder bitumen and cover aggregate shown in the contract documents or specified herein are approximate and may be varied as found desirable on the basis of laboratory or field tests.

A. Preparation of Surface.
Immediately before bitumen is applied, the Contractor shall clean the entire surface to be treated and the adjacent gutters of all foreign material, including dust. This work shall include all blading, cleaning, and incidental work required to produce a clean surface. If the power broom fails to remove dust from depressions and pockets, hand brooms shall be used. Material removed from the road surface in rural areas shall be bladed or swept off the road surface. In cities and towns, the material shall be removed in accordance with Article 1104.08 and become the property of the Contractor.

Priming, if required, will be specified in the contract documents.

B. Heating Bituminous Materials.
Bituminous materials shall be heated to a temperature which will permit uniform spreading. It is estimated that temperatures between these limits will produce the desired viscosity:

Designation	Temperature, °F* (°C)
CRS-1 and 2 and CRS-2P	150-185 (65-85)
MC-800	175-255 (80-125)
MC-3000	215-290 (100-145)
MC-70	145-165 (60-75)
* Some temperatures listed may be above the flash point of the material. Extreme caution shall be used in handling such material to reduce fire hazard.

Material which has been damaged by overheating will be rejected.

C. Spreading Bituminous Material.

1. General.
Bituminous material shall not be spread until the distributor complies with recommendations of the manufacturer as to nozzle size, nozzle angle with the axis of the spray bar, and spray bar or nozzle height above the road surface, and until the distributor has been tested to assure uniform distribution of bitumen on the road surface at the specified rate.

Adjacent applications of bitumen shall close with minimum longitudinal lap. The quantity of bituminous material spread shall be between 95% and 105% of the quantity prescribed by the Engineer. The rate of application shall be corrected for temperature to deliver the desired volume at 60°F (16°C).

Curbs and handrails of bridges, guardrails, headwalls of culverts, pavements, curbs and gutters, utility accesses, intakes, water and gas valves, railroad flangeways, and other installations requiring protection shall be protected by a suitable covering to prevent them from being soiled by bitumen, and it shall remain in place until the bitumen has set and no splashing occurs under traffic. Suitable covering shall also be placed as required to prevent cover aggregate from entering intakes, or other similar structures during placement and while brooming excess cover aggregate.

The Contractor shall preserve the integrity of areas with rumble strip panels. This may include suitable covering to be placed which prevents filling with bituminous seal coat or hand labor for strip restoration if not covered, at the Contractor's option and subject to the approval of the Engineer.

2. Binder.
The surface on which binder bitumen is to be applied shall be swept clean of all loose aggregate and foreign material which may prevent adhesion of the binder to the surface on which it is applied. This applies to fillets at intersecting roads and drives only when specified.

Binder bitumen shall then be applied to the surface, including fillets at intersecting roads and drives when specified, at the rates and in the manner specified or designated by the Engineer.

When traffic must be maintained through the work while construction is in progress and the width is 24 feet (7.2 m) or less, the bituminous seal coat shall be placed in two passes. For the first course of two course bituminous seal coat, the spreading of bitumen for the first lane shall be approximately 12 inches (0.3 m) wider than one-half the pavement width of the pavement to be surfaced. For other courses, the spreading of bitumen for each lane shall be approximately one-half the width of the pavement to be surfaced. In addition, the direction of progress shall be the direction from which aggregate is to be hauled to the spreader, and one side shall be completed for one day's run before the seal coat is applied on the adjacent lane. Auxiliary lanes may be done on the same day. One side may be completed for the full length of a short project before the seal coat is applied to the other side. However, it is the intention of this specification that the maximum length of road with new seal coat on only one side would be limited to approximately 6 miles (10 km). This length may be increased with approval of the Engineer.

The length of any spread shall not be more than can be covered with aggregate and the rolling completed within 30 minutes. In addition, the distance between the bitumen distributor and the aggregate spreader shall be a maximum of 150 feet (45 m), and the initial roller coverage shall be as close to the aggregate spreader as possible, not to exceed 200 feet (60 m). In any case where emulsion is used, the binder bitumen shall be covered with aggregate and initially rolled within 2 minutes after the bitumen has been spread. When the 2 minute requirement for emulsion or the 30 minute requirement for all work is not met, the work may be considered as not in reasonably close compliance and may be subject to evaluation in accordance with Article 1105.04.

Binder bitumen for winter seals shall be applied with limitations which the Engineer deems appropriate; other binder bitumen shall be applied only when the road surface is free of moisture and has a temperature not lower than 60°F (15°C). When the environment places a portion of the pavement in shade, the temperature shall be determined in a shaded area.

3. Joints.
Uniform distribution of binder bitumen, at the specified rate of application, shall be secured at transverse joints by the use of paper placed at the start of each distributor run. When the end of the run joins newly placed seal coat, paper shall be placed at that joint also. The joint shall be a cut straight along the off edge of the paper, and the seal coat material on the paper adjacent to the off edge shall be removed from the roadbed surface. The paper shall be commercial grade building paper, subject to approval of the Engineer. It shall be not less than 36 inches (0.9 m) wide. Care shall be taken to obtain a smooth riding surface.

D. Spreading Cover Aggregate.

1. General.
Mechanical spreaders of the type specified shall be used to spread cover aggregate on the freshly applied bitumen. Care shall be used to prevent spillage or piling of aggregate. Spillage or piling shall be corrected by manual methods before rollers cover the area. At no time shall the ballast in rollers be used for spreading aggregate. Vehicles other than those required to deliver aggregate to the spreader will not be permitted to pass over the treated area of the roadbed until after the aggregate has been spread and rolled.

The surfacing of fillets at intersecting roads and drives may be placed subsequent to that on the roadbed proper, but in any case shall promptly follow spreading of binder bitumen.

2. Moisture.
At the time of spreading, the surfaces of the cover aggregate shall be damp, but with no free water. This will be determined by visual inspection.

E. Rolling.
Rolling shall follow promptly after the aggregate has been spread to secure early embedment of the aggregate in the bitumen. As a maximum, rolling shall be completed within 30 minutes after the bitumen is spread.

Succeeding applications of binder bitumen shall not be applied until the most recent one applied has been covered with aggregate and all rolling operations completed.

Satisfactory embedment usually will be secured by one roller coverage of sand cover and five roller coverages of other cover aggregate. One roller coverage shall be interpreted as the number of passages of the roller required to insure that the entire area has been touched at least once by the entire roller. Rollers shall be operated at a speed not exceeding 5 mph (8 km/h).

F. One Course Seal Coats.
In addition to requirements of Paragraphs D and E, the following shall apply:

1. Spreading Binder Bitumen.
Bitumen shall be applied to the prepared base or surface at the rate designated by the Engineer, usually within the following ranges:

Aggregate Size	Spreading Rate Gal. /Sq. Yds. (L/m2)	Basic Rate* Gal. /Sq. Yds. (L/m2)
Sand	0.15 - 0.20 (0.7 -0.9)	0.15 (0.8)
3/8 inch (19 9.5 mm)	0.25 - 0.35 (1.1 - 1.6)	0.30 (1.4)
1/2 inch (12.5 mm)	0.35 - 0.45 (1.6 - 2.0)	0.40 (1.8)
* The basic rate will be used for design purposes.

2. Spreading Cover Aggregates.
Promptly after the spread of bitumen has been completed on any section, cover aggregate of the size specified shall be spread uniformly over the treated area. Unless otherwise specified, the rate shall be 10 pounds per square yard (5 kg/m²) for shoulders, 15 pounds per square yard (8 kg/m²) for winter seals, and 30 pounds per square yard (16 kg/m²) for other applications.

When bituminous seal coat is placed on two lanes, the width of spread of aggregate for the first lane shall be 50% the width of roadway to be treated.

G. Two Course Seal Coats.
In addition to requirements of Paragraphs D and E, the following shall apply:

1. First Course Construction.

a. Spreading Binder Bitumen.
Bitumen shall be applied to the prepared base or surface at the rate of 0.35 gallon per square yard (1.6 L/m²).

b. Spreading Cover Aggregate.
Promptly after spreading bitumen on any section, cover aggregate of the size specified shall be spread uniformly over the treated area at the rate of 30 pounds per square yard (16 kg/m²).

When bituminous seal coat is placed in each lane separately, the width of spread of aggregate for the first lane shall be 1 foot (0.3 m) greater than 50% of the width of the lane to be surfaced.

When the full width is surfaced integrally, the width of spread shall be such that the junction of the two aggregate spreads shall be offset 1 foot (0.3 m) from the center of the full width surface.

2. Second Course Construction.

a. Preparation of Roadbed.
After completion of the first course, the roadbed shall be prepared for the second course with a vacuum machine or by lightly brooming the full surfaced width with the power sweeper to remove any loose material. After cleaning, the entire surface shall be rolled once with the steel roller.

The preparation of roadbed shall be completed in sections just prior to application of bitumen for the second course.

b. Spreading Binder Bitumen.
Bitumen shall be spread on the prepared surface at the rate of 0.30 gallon per square yard (1.4 L/m²).

c. Spreading Cover Aggregate.
Promptly after spreading bitumen on any section of roadbed, cover aggregate of the size specified shall be spread over the treated area at the rate of 25 pounds per square yard (14 kg/m²).

For two lane roadways, the two spreads of aggregate shall be placed so the seam between the two spreads is near the centerline.

H. Maintenance During Construction Period.
If bleeding occurs during construction, the Engineer may order additional aggregate placed at the contract price for cover aggregate. Additional compensation will not be allowed for incidental rolling.

On Primary projects and where specified on other projects, the surface shall be gently swept free of all loose cover aggregate with a rotary broom early the next morning while the bituminous binder is hard and stuck particles will not be disturbed. Other means of removing the loose particles, such as vacuum machines or air blast, may be used with approval of the Engineer. In areas with curb and gutter sections or storm sewer intakes, this shall include collection of the loose cover aggregate and hauling it off the project. Hauling of loose cover aggregate may also be included in additional areas, such as at entrances or shallow drainage ditch locations, within municipal corporate limits, if designated by the Engineer.

Additional sweeping may be required by the Engineer to remove loose cover aggregate from the surface throughout the project duration.

When the contract includes an item for asphalt emulsion for dust control, the dust control shall be applied following the removal of loose particles and before other work may continue. This shall be in accordance with Paragraph I.

I. Dust Control Treatment.
The Contractor shall apply dust control following the removal of particles and before other work may continue. It shall also be applied within 24 hours after BSC placement unless otherwise directed by the Engineer.

Diluted asphalt emulsion shall be uniformly spread at the initial rate of 0.12 gallon per square yard (0.5 L/m²).

The Contractor shall broom off loose material and apply dust control on the calendar day following placement of BSC.

J. Traffic Control
When the road is not closed for construction, normal traffic shall be maintained on the project at all times, and a detour will not be provided. Traffic shall not be delayed unnecessarily. Traffic maintenance during work on shoulders of multilane pavements shall be as shown in the contract documents.

Traffic control setups, which unnecessarily cause stopping or turning movements, generally will not be allowed.

Unless stated otherwise in the contract documents, the Contractor shall furnish the signs and mounting devices including posts.

The Contractor shall furnish and install these signs as follows:

1. "NO PAVEMENT MARKINGS NEXT ____ MILES" signs. These signs shall be placed at each end of the area where pavement markings have been obliterated, on each side of towns, and on each side of all intersections with Primary and Secondary Roads.

2. "LOOSE STONE - REDUCE SPEED" signs with a 35 mph advisory speed plate placed approximately 500 feet (150 m) in advance of the "No Pavement Markings" signs.

3. "DO NOT PASS" signs. These signs shall be placed on the right-hand side of the road at the beginning of each no-passing zone.

4. "PASS WITH CARE" signs. These signs shall be placed on the right hand side of the road at the end of each no-passing zone.

All signs shall be mounted on posts.

The Contracting Authority will place new pavement markings and remove the signs when the project is complete.

Provisions for handling other traffic are as follows:

Traffic shall be directed through restricted portions of the project with pilot cars described in Article 2528.04. The Contractor shall furnish pilot cars and pilot car signs.

One flagger shall be stationed immediately ahead of the application of the bitumen, one flagger immediately behind the bitumen, and one flagger immediately behind the section being rolled. Suitable warning, speed limit, and fresh oil signs shall be displayed, and the signs shall be moved forward with the flagger as the work progresses.

After the bituminous seal coat has been spread, smoothed, rolled, and cured for a minimum of 2 hours, the road may be open to traffic. In areas where it is more practical to place the bituminous seal coat in short sections and to allow traffic to use the completed bituminous seal coat immediately after the surface treatment has been completed, traffic shall be controlled on the newly placed bituminous seal coat to a speed not to exceed 25 mph (40 km/h) for a minimum of 2 hours. Such areas will be specifically authorized by the Engineer. The Engineer may extend the minimum 2 hour period due to low temperature and visually observed damage to the bituminous seal coat under traffic or when turning movements may damage the bituminous seal coat. (The intent of traffic modifications is to not allow traffic on completed bituminous seal coat sections until satisfactorily cured; this requires a minimum of 2 hours, depending on climatic conditions.)

K. Limitations.
The Engineer may prohibit construction if the weather is unfavorable for the embedment of cover aggregate in the binder bitumen as specified in Article 2307.04, C.

The area on which binder bitumen is spread shall not be greater than the area that can be covered with aggregate, and the rolling completed, within daylight hours of the same working day. When traffic is being carried through the work, the entire roadbed shall be free of construction equipment in accordance with Article 1107.08.

Except for winter seals, seal coats shall not be applied after September 1 on Primary projects or after September 15 on other projects. When the entire project cannot be completed by the specified cutoff date, placement shall not be on one side only for the full length of the project, and both sides shall be completed to the same location by the specified cutoff date.

When pavement marking is part of the work of this contract, the construction of the traffic lines shall be completed at a location within 72 hours after the seal coat has been completed to the full width at that location, weather permitting.

When dust control treatment is required, it shall be allowed to cure prior to allowing traffic on the roadway.

L. Surfacing Intersecting Roads, Driveways, and Turnouts.
Unless otherwise specified in the contract documents, at driveways to farmsteads and commercial establishments, the area of any fillets of base courses constructed shall be covered with seal coat at the rate provided for the roadway. The remaining areas within the right-of-way on earth or gravel surfaced approach roads and driveways and all turnouts for mail boxes shall be surfaced, measured, and paid for in accordance with Section 2315.