CENTER
OF HOPPER - AREA 2 The
tailgate on the hauling units acts as a strike off and starves this
area allowing the material to drop below the height of the flow gates
forming a stream of segregation down the center of each conveyor. This
can be helped by making sure the discharge from the hauling unit is
not restricted by the tailgate or the tailgate being chained too closely
thus reducing the flow from the hauling unit below the quantity needed
for continuous paving. Make sure, during the truck exchange this same
problem is not allowed to happen by running the hopper below the 30%
capacity.
Use of a Materials Transfer Vehicle (MTV) such as the Blaw-Knox MC-30
together with a Twin Pub Tub receiving and re-mixing device, will greatly
reduce the truck to paver problems.
FRONT
OUTSIDE CORNERS OF THE HOPPER - AREA 3 This
problem appears mostly when using "Pick-Up" machines or "Transfer
Units" without a hopper insert. The material peaks in the center
and a sinkhole appears at each outside corner funneling segregation
down the outside of each conveyor and into the mat being laid. Combat
this problem by maintaining the minimum material level in the hopper
to approximately 30%.
MATERIAL SPILLAGE - AREA 4 When
the hauling unit is discharging into the paver hopper, the material
overflows the hopper and spills out onto the grade on both sides of
the paver. This situation can be compounded by damaged or torn overflow
guards that are supposed to retain the material in the hopper during
the exchange process. The material leaving the hopper and falling on
the grade can be large, segregated material because it is flowing from
the outside of the truck bed, in and then out of the hopper onto the
grade. Once paved over, this type of segregation is not normally noticeable
from the surface and can go undetected showing up later as longitudinal
cracking. Replacing worn overflow guards and monitoring the volume in
the hopper that it is not allowed to fall onto the grade should reduce
or eliminate this problem.
The
tailgate on the hauling units acts as a strike off and starves this
area allowing the material to drop below the height of the flow gates
forming a stream of segregation down the center of each conveyor. This
can be helped by making sure the discharge from the hauling unit is
not restricted by the tailgate or the tailgate being chained too closely
thus reducing the flow from the hauling unit below the quantity needed
for continuous paving. Make sure, during the truck exchange this same
problem is not allowed to happen by running the hopper below the 30%
capacity.
This
problem appears mostly when using "Pick-Up" machines or "Transfer
Units" without a hopper insert. The material peaks in the center
and a sinkhole appears at each outside corner funneling segregation
down the outside of each conveyor and into the mat being laid. Combat
this problem by maintaining the minimum material level in the hopper
to approximately 30%.
When
the hauling unit is discharging into the paver hopper, the material
overflows the hopper and spills out onto the grade on both sides of
the paver. This situation can be compounded by damaged or torn overflow
guards that are supposed to retain the material in the hopper during
the exchange process. The material leaving the hopper and falling on
the grade can be large, segregated material because it is flowing from
the outside of the truck bed, in and then out of the hopper onto the
grade. Once paved over, this type of segregation is not normally noticeable
from the surface and can go undetected showing up later as longitudinal
cracking. Replacing worn overflow guards and monitoring the volume in
the hopper that it is not allowed to fall onto the grade should reduce
or eliminate this problem.