fluctuations in temperature could indicate a moisture change within the stockpiles or a bin cold feed that has malfunctioned.
The Contractor shall provide a means of diverting the flow of asphalt concrete away from the silo to prevent incompletely mixed asphalt concrete from entering the silo. The device is also referred to as the reject chute, and is used to divert asphalt mixtures away from the silo that do not meet the minimum and maximum specifications. The Plant Inspector must determine when the completed AC mix is homogeneous and at the proper temperature before allowing the plant operator to close the reject chute. The Plant Inspector must always reject any asphalt concrete that exceeds the temperature requirements specified for the project.
The requirements for a Caltrans QC/QA project specify, an automatic continuous recording device be provided to document the asphalt concrete mix temperature during all hours of production. Caltrans also specifies, when a recording type temperature indicator is used, it shall be maintained in a working condition.
Storage Silos The completed AC mixture travels from the drum mixer or pugmill mixer to the top of the storage silo by belt conveyor or a slat conveyor. Caltrans specifies, "Storage silos shall be equipped with a surge- batcher sized to hold a minimum of
4000 pounds of material.
batcher consists of equipment
surge- placed which
the completed mix,
prevents the segregation of product ingredients as the completed mix is placed into storage. The surge- batcher is to be thermally insulated
A surge batcher is located between the top of the slat conveyor and the top of the storage silo.
Discharge gates on surge-batchers must be automatic and discharge only
after 4000 pounds of AC mix have been collected. timers are not allowed.
Discharge gates operated by interval
Asphalt concrete shall not be stockpiled. When asphalt is stored, it shall be stored only in silos. AC storage silos typically hold between 75 to 200 tons of mix and are insulated and heated. Caltrans requires a 20 ton minimum be retained in the storage silo during AC production, except for the period immediately following a shutdown of the plant of two hours or more. A device shall be provided at the plant control panel, indicating the