506 - Slurry Seal
GENERAL
Pre-Paving Meeting
A pre-paving conference between the Contractor and the Engineer should be held on site prior to beginning work.
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Contractor’s detailed work schedule. |
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Traffic control plan. |
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Overall safety plan. |
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Equipment calibration. |
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Review of Contractor’s mix design. |
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Troubleshooting procedures. |
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Condition and adequacy of equipment. |
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Exchange list of personnel assigned to the project. |
MATERIALS
The asphalt emulsion must be certified and supplied by an approved supplier. The mix design and quality control testing is the responsibility of the Contractor. The MDOT inspector must ensure that a proper mix design and JMF have been established and that the Contractor is performing the specified quality control testing. The inspector must also ensure that the proper daily documentation is received from the Contractor.
CONSTRUCTION
Site Preparation
All loose materials, vegetation, dirt, mud and other objectionable material shall be removed from the surface prior to placing the mixture. If a bond coat is required, it shall be allowed to cure before placement of the mixture is permitted.
Weather Limitations
Placement of the mixture is not permitted if there is rain, or threatening weather, and temperatures are forecast to be below 32°F (0°C) within 24 hours of completion of the work. The mixture shall not be placed if the air or pavement temperature is below 45°F (7°C).
Traffic Control
Traffic shall not be allowed on the mixture until it has cured sufficiently to prevent pick up by vehicle tires.
Equipment
Equipment shall be safe, environmentally acceptable and capable of producing a specification product. A typical product will have some, or all, of the following equipment on the project.
Slurry Seal Mixer
The slurry seal mixing machine shall be a continuous flow mixing unit with calibrated controls capable of delivering accurately predetermined proportions of aggregate, water and asphalt emulsion to the mixing chamber, and of discharging the thoroughly mixed product on a continuous basis. No violent mixing will be permitted. The aggregate shall be wetted in the pug mill immediately prior to mixing with the emulsion.
The machine shall be capable of a minimum speed of 10 feet (2 meters) per minute and shall not exceed 150 feet (55 meters) per minute while in operation. The machine shall have enough storage capacity to properly mix and apply a minimum of 6 tons of slurry seal.
An approved means of measuring all materials used in each slurry seal batch shall be provided by the Contractor and made accessible to the Engineer.
Spreading Equipment
Attached to the mixing machine shall be a mechanical type single squeegee distributor equipped with flexible material (the drag) in contact with the pavement surface to prevent loss of slurry and adjustable in width with a flexible strike off. This drag shall not cause grooving of the slurry. It shall be kept clean and no material buildup will be allowed. The drag type, burlap or other textile, will be approved by the Engineer and it shall be changed as frequently as need, or as designated by the Engineer.
Miscellaneous Equipment
Hand squeegees, shovels and other equipment shall be used as necessary to perform the work. Cleaning equipment, such as power brooms, air compressors, water flushing equipment and hand brooms should be adequate for surface preparation.
MEASUREMENT AND PAYMENT
Delayed Acceptance
The Contractor is responsible for placing a uniform product. This type of work has a 30 day delayed acceptance procedure so that any major problems will be corrected by the Contractor before the project can be accepted. In most cases, the inspector has little to do with the slurry operation itself, but must ensure that traffic control is conducted properly and that all safety rules are followed.
If the inspector notices a nonuniform application, any traffic control or safety violations, the Contractor must be notified immediately. If the Contractor does not correct the violation, the project should be stopped.