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Frequently Asked Soil-Cement Questions
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> Soil-Cement > Soil-Cement FAQs > Pugmills
How exactly does a pugmill work to blend materials
together for CTB?
 Pugmills
provide excellent mixing for cement-treated materials because of
the violent action of the mixing process. Typically a pugmill will
have two horizontal shafts, each with dozens of paddles. The shafts
turn in opposite directions, causing one set of paddles to turn
clockwise, and the other set to turn counter-clockwise. This motion
hurls the particles toward each other in a violent action that allows
for uniform mixing.
The pugmill operates on a continuous basis, with an aggregate feed
belt, water spray, and cement vane that are all computer controlled
to provide accurate metering of the constituents. Pugmills can be
set up with more than one silo, so cementitious products (such as
portland cement and fly ash) can be blended at the plant.
The mixed material is taken by belt to a surge hopper (or gob hopper)
where it will be dumped into a truck to be transported to the job
site. The trucks will have tarps to cover the freshly mixed material
so that moisture is not lost on the way to the site.
Pugmills on paving projects are typically portable, and can be
set up and running in less that a day. Production for pugmills on
these projects are normally in the range of 300 – 500 tons
per hour.
Click here for a diagram of a
pugmill layout.
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