To respond to the new CALTRANS specification for adding Liquid Anti-Strip (LAS) to asphalt on some of its contracts, Wilderness Technology, Inc. has manufactured 2 systems.

One system is for continuous feed drum plant that inject the LAS into the asphalt before it enters the drum. The other system is for use on batch type asphalt plants.

Right now (OCT. 2002) we have 3 Continuous Feed Drum plants and 2 Batch plants installed and CALTRANS test 109 certified.

The CALTRANS specification: ( As I write this, the finished specification is not complete and I will not try to cover all of it, just some highlights and how our systems meet them.)

• LAS shall be added at a rate of between 0.5% and 1.0% by mass of the asphalt binder.
• System accuracy shall be 0.5%
• The LAS that you use must be compatible with the asphalt binder. (Your asphalt supplier will be able to tell you this.
• Batch plants will be proportioned by mass and dispensed into the flow of asphalt as it enters the pug mill. This can be weighed by a scale or measured by a coriolis flow meter. Our system weighs the LAS.
• Continuous Mixing plants will be proportioned by mass and injected into the asphalt binder after it has been proportioned to the aggregate, but before entering the mixing chamber. The LAS shall be proportioned by a coriolis flow meter. Our system uses a Micro Motion® coriolis flow meter.
• The LAS system must run in automatic, tied to the asphalt plant control system.
• The LAS storage shall have a level indicator that will stop the plant if the LAS drops too low for proper operation.

These are the basics of the specification except for the data collection.

CONTINUOUS FEED ASPHALT PLANT - Our Liquid Anti-Strip system for this type of plant has a separate control box that is installed in the control room for the plant. This box contains the transmitter for the coriolis meter, the controller for LAS proportioning and circuitry. When you are not using LAS in your asphalt, you turn off the system with a button. A pump box is outside by the asphalt pump. This box contains the coriolis flow meter, pump, and valves to control the flow rate of the LAS. Two cables run between the control box and the pump box. A heated storage container is necessary to feed the LAS from. Because of the need to meter the LAS by mass as a percentage of mass of the asphalt binder, the asphalt plant needs to have a coriolis flow meter on the asphalt. It may be possible to do this using a meter like the Digiflow®, but we have only installed the systems on plants that have coriolis flow meters on the asphalt.

BATCH TYPE ASPHALT PLANT - This LAS system has three (3) boxes. The control box is installed in the plant control room, has the ability to run in automatic or manual. The second box is the pump box and is located on the ground below the batch plant, this box contains the pump to supply the LAS to the box on the plant. The third box is the plant box mounted by the asphalt weighing pot. It contains the scale and injection pump to inject the LAS into the flow of asphalt as it enters the pug mill. A heated storage container is necessary to feed the LAS from.

Our systems are separate from your asphalt plant controls, if you have an old controller, we can still tie into your controller and run in full automatic. When you are not making asphalt that requires LAS, you just turn the system OFF. Many of the plant controllers say they can control the LAS additive flow, but many require a software upgrade and possibly hardware changes.

Heated storage of the LAS is necessary for consistent flow. We will be offering a tank with heaters and the level indicator required by CALTRANS.

If you have any questions or concerns about your needs for a Liquid Anti-Strip system please call or email me.

Wilderness Technology,Inc.
22160 Lassen View Dr.
Palo Cedro, CA 96073
(530) 547-5682