Note: Descriptions are shown in the official language in which they were submitted.
CA 02354415 2001-07-31
METHOD OF IN-SITU REJUVENATION OF
ASPHALT PAVEMENT
FIELD OF THE INVENTION
This invention relates to methods of in-situ rejuvenation of asphalt pavement.
More particularly
this invention relates to a method of breaking up and rejuvenating an asphalt
surface in the region
proximate to an obstruction, such as an access cover.
BACKGROUND OF THE INVENTION
Asphalt pavement consists essentially of an aggregate and sand mixture held
together with a
petroleum based binder, such as tar. With continued exposure to sun, moisture,
traffic, freezing
and thawing, asphalt surfaces degrade. The degradation is principally in the
binder, rather than
the aggregate and sand mixture which makes up the bulk of the asphalt. Also,
much of the
degradation occurs within the top two or three inches of the surface.
Traditionally, worn asphalt pavement was not restored but instead was torn up
and replaced with
new asphalt. This is a costly approach and creates a problem as to what to do
with the torn up
pavement. Accordingly, techniques and apparatus have been developed for
restoring or
rejuvenating the top few inches of an asphalt paved surface.
A typical road resurfacing apparatus has a heater for heating and softening
the asphalt surface as
it passes along the asphalt surface. Following the heater is a "rake" or
"scarifier" which breaks
up or "scarifies" the softened pavement. The scarified pavement is generally
crushed or
"milled", blended with rejuvenating fluid (and optionally, additional sand or
aggregate) and
redeposited. The redeposited material is spread out and rolled to create a
rejuvenated surface
comparable in quality to the original surface before degradation.
Asphalt paved surfaces generally include embedded objects such as access
covers and culverts
which act as obstructions, and interfere with pick-up of the scarified and/or
milled material prior
to creation of the rejuvenated surface. The rake generally rides over such
objects and does not
scarify the proximate area. This necessitated separate treating of the areas
around such obstacles
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which has traditionally been done using manual techniques (picks and shovels).
The use of
manual treating is generally slow and often doesn't promote adequate depth of
scarification.
It is an object of the present invention to provide a method using a
mechanized apparatus for
facilitating removal of scarified and/or milled asphalt material from around
obstructions in the
road surface.
SUMMARY OF THE INVENTION
The present invention provides a method of effecting in-situ rejuvenation of
an asphalt paved
surface with an asphalt rejuvenating apparatus comprising a pick-up conveyor
and a backhoe
apparatus, wherein the asphalt paved surface includes an obstruction disposed
therein,
comprising the steps of (a) heating the asphalt paved surface to form heated
asphalt, (b)
scarifying the heated asphalt to form a scarified intermediate, (c) milling
the scarified
intermediate to form a milled intermediate, (d) adding rejuvenating fluid to
the milled
intermediate to form a blended intermediate, wherein the blended intermediate
is deposited
proximate the obstruction, and (e) moving the blended intermediate from
proximate the
obstruction to the entrance to the pick-up conveyor with the backhoe
apparatus.
In one aspect, the present invention relates to the method described above,
wherein, during Step
(d), the blended intermediate is deposited behind the obstruction relative to
the entrance to the
pick-up conveyor.
In a further aspect, the present invention relates to any of the methods
described above, wherein
the backhoe apparatus moves laterally relative to the asphalt paved surface
connecting the
blended intermediate to the entrance to the pick-up conveyor.
In a further aspect, the present invention relates to any of the methods
described above, wherein
the backhoe apparatus is rotatably mounted to the asphalt rejuvenating
apparatus for rotation
about an axis perpendicular to the asphalt surface. In one embodiment, the
backhoe apparatus
is rotatably mounted to the pick-up conveyor.
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In yet another aspect, the present invention relates to any of the methods
described above,
wherein the backhoe apparatus is retractable.
In yet a further aspect, the present invention relates to any of the methods
described above,
wherein the backhoe apparatus is configured to move vertically relative to the
asphalt paved
surface.
In another aspect, the present invention relates to the any of the methods
described above,
wherein the asphalt rejuvenating apparatus further comprises a heater, a
raking device, a main
mill, and a pug mill, and wherein the heater heats the asphalt paved surface
to form the heated
asphalt, the raking device dislodges the heated asphalt to form the scarified
intermediate, the
main mill grinds the scarified intermediate to form the milled intermediate,
and the pug mill adds
the rejuvenating fluid to the milled intermediate to form the blended
intermediate.
In a further aspect, the present invention relates to any of the methods
described above, wherein
the blended intermediate is dragged to the entrance to the pick-up conveyor by
the backhoe
apparatus.
The present invention also provides a method of effecting in-situ rejuvenation
of an asphalt
paved surface with an asphalt rejuvenating apparatus comprising a pick-up
conveyor and a
backhoe apparatus, wherein the asphalt paved surface includes an obstruction
disposed therein,
comprising the steps of (a) heating the asphalt paved surface to form heated
asphalt, (b)
scarifying the heated asphalt to form a scarified intermediate, (c) milling
the heated asphalt to
form a milled intermediate, wherein a portion of the milled intermediate is
deposited proximate
to the obstruction, and (d) moving the milled intermediate from proximate the
obstruction to the
entrance to the pick-up conveyor with the backhoe apparatus.
The present invention also provides a method of effecting in-situ rejuvenation
of an asphalt
paved surface with an asphalt rejuvenating apparatus including a pick-up
conveyor and a backhoe
apparatus, wherein the asphalt paved surface includes an obstruction disposed
therein,
comprising the steps of heating the asphalt paved surface to form heated
asphalt, scraping and
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pulling the heated asphalt proximate to the obstruction with the backhoe
apparatus to form a first
intermediate, and moving the first intermediate from proximate the obstruction
to an entrance
to the pick-up conveyor with the backhoe apparatus.
DESCRIPTION OF THE DRAWINGS
The embodiments of the present invention are described below with reference to
the
accompanying drawings in which:
Figure 1 is an illustration of an asphalt rejuvenating apparatus for carrying
out the method of the
present invention;
Figures 2 to 7 are side elevation views of the backhoe apparatus and pick-up
conveyor of the
asphalt rejuvenating apparatus in Figure 1, in various positions of
orientation; and
Figures 8 to 10 are top plan views of the backhoe apparatus and pick-up
conveyor of the asphalt
rejuvenating apparatus of Figure 1, illustrating obstructions in the road
surface disposed in
different positions relative to the entrance to the pick-up conveyor, and
further illustrating the
movement of the backhoe apparatus in carrying heated, raked, and milled
asphalt from around
the obstructions and towards the entrance to the pick-up conveyor.
DETAILED DESCRIPTION
A typical asphalt rejuvenating apparatus is generally indicated by reference
numeral 10 in Figure
1. The rejuvenating apparatus 10 travels in a path of travel indicated by
arrow 12 upon asphalt
surface 18. An obstruction 19, such as an access cover, culvert pipe, manhole,
or utility structure
is disposed within the asphalt surface 18.
A power plant 14 at the front is provided to drive the apparatus and typically
includes an engine
and a hydraulic system. Behind the power plant 14 is a heater box 16 which
includes numerous
burners and associated plumbing for heating the asphalt surface 18. A propane
(or other
combustible fuel) tank 20 and a combustion blower 22 would typically be
provided. The heater
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box 16 directs heat at the asphalt surface 18 to cause softening of an upper
part of the asphalt
surface 18.
The softened asphalt surface 18 is initially dislodged by a raking device,
generally indicated by
reference 100 which follows the heater box 16. The raking device 100 is
described in more detail
below, after a brief overview of the overall layout and operation of the
asphalt rejuvenating
apparatus 10. The rakes 100 dislodge the heated asphalt surface 18. The rakes
100 may include
main rakes 102 and extension rakes 104, the extension rakes 104 performing a
similar function
to the main rakes 102, but to the outside edges. The main rakes 102 break up
material around
manholes where a main mill 36 behind the rakes 100 cannot run.
The main mill 36 grinds up the material dislodged by the rakes, levels the
underlying surface and
prepares the surface to a preset depth. Extension mills 38 ahead of the main
mill 36 perform a
similar function, but process outer material typically from 10 to 15 feet to
each side of the
rejuvenating apparatus 10 and move it to a central part of the rejuvenating
apparatus 10 where
it is subsequently processed by the main mill 36.
A pug mill 40 follows the main mill 36 and mixes the processed material from
the main mill 36
with rejuvenating fluid from a tank 42. Blended material 46 from the pug mill
40 is picked up
by a pick-up conveyor 44 through its entrance 45. The pickup conveyor 44
deposits the blended
material 46 in a heated holding hopper 48. The holding hopper 48 keeps the
blended material
46 hot until it is needed. The holding hopper 48 may be filled through its top
with material for
start ups or if additional material is needed. The holding hopper 48 may also
be dumped if
required or at the end of a day's operation.
A screed 50 follows the asphalt rejuvenating apparatus 10 and may be a unit
such as typically
found on an asphalt payer. The screed 50 lays, spreads and slightly compacts
the blended
material 46 for final rolling.
A water system 52 may be provided to supply cooling water to front and rear
tires or tracks 54.
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An operator 56 operates a control and processing station 58. The operator 56
can input and
monitor the amounts of rejuvenating fluid, sand and aggregate being added, as
well as control
operation of a backhoe apparatus 200, to be described in further detail below.
A sand/aggregate bin 60 precedes the asphalt rejuvenating apparatus 10. The
sand/aggregate bin
60 may be attached to the asphalt rejuvenating apparatus 10 or attached to a
separate machine
(not shown) running in front thereof. Sand/aggregate is metered at a specific
rate which is a
function of ground speed and specification requirements.
The rejuvenating apparatus 10 is provided with the backhoe apparatus 200 to
facilitate
rejuvenating of asphalt surface 18 in a region proximate to, or in the
vicinity of, the obstruction
19. The backhoe apparatus 200 is configured for lateral movement relative to
the asphalt surface
18 connecting the blended material 46 and the entrance 45 to pick-up conveyor
44. Further,
backhoe apparatus 200 is configured for vertical movement, relative to the
plane defined by the
asphalt surface 18, as well as retractable movement in the general direction
from the blended
material 46 and to the entrance 45 of the pick-up conveyor 44.
The backhoe apparatus 200 is rotatably mounted to a frame 202 of the rej
uvenating apparatus 10.
In one embodiment, and as illustrated in Figure 1, the pick-up conveyor 44
includes the frame
202. In this respect, the backhoe apparatus 200 is, therefore, rotatably
mounted to pick-up the
conveyor 44. Rejuvenating apparatus 10 includes hydraulic motors (not shown)
to effect rotation
of the backhoe apparatus 200 relative to the pick-up conveyor 44.
Referring to Figures 2 to 7, the backhoe apparatus 200 includes a boom 204, an
arm 206,and a
blade 208. The boom 204 has one end pivotally connected at 210 to the frame
202, and the other
end pivotally connected at 212 to one end of the arm 206. The other end of the
arm 206 is
pivotally connected at 214 to a base end of the blade 208. The blade 208 has a
scraping end 216
away from the base end.
A double-acting linear actuator 2181, such as a fluid pressure actuated
cylinder, is operatively
connected between the frame 202 and the boom 204 for controlling the pivotal
movement of the
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boom 204 about the pivot point 210. Similarly, another double-acting linear
actuator 2182 is
operatively connected between the boom 204 and the arm 206 for controlling the
pivotal
movement of the arm 206 about the pivot point 212. A further double-acting
linear actuator 2183
is operatively connected between the arm 206 and the blade 208 for controlling
the pivotal
movement of the blade 208 about the pivot point 214.
Figures 2 to 7 illustrate the backhoe apparatus 200 of the present invention
in various
orientations. Figure 2 illustrates backhoe apparatus wherein the boom 204 is
fully raised, the arm
206 is fully extended and the blade 208 is disposed in a fully retracted
position. Figure 3 is
similar to Figure 2, with the exception that the blade 208 is disposed in the
fully-retracted
position. Figure 4 illustrates the backhoe apparatus in a different
orientation, wherein the boom
202 is fully raised, and the arm 206 is disposed in the fully tucked position.
Figure 5 illustrates
the backhoe apparatus with the boom 204 lowered to effect contact of the blade
208 with the
asphalt paved surface 18, and with the arm 206 and the blade 208 fully
extended. In this
orientation, the blade 208 makes contact with the processed asphalt surface
18, which has been
previously subjected to preheating, raking, and milling. Figure 6 illustrates
the backhoe
apparatus 200 with the boom 204 lowered, and with the arm in the tucked
position, and the blade
208 in a fully extended position to reach an edge of the obstruction 19.
Figure 7 illustrates the
backhoe apparatus 200 with the boom 204 lowered, and with the arm 206 in the
tucked position,
and with the blade 208 in the retracted position.
In one embodiment, backhoe apparatus 200 is BRADCOTM Model No. 6L9.
After heating, raking and milling of asphalt surface 18 by the rejuvenating
apparatus 10, material
may collect in the region proximate to, or in the vicinity of, the obstruction
19. The obstruction
19 obstructs the pick-up conveyor 44, and makes it difficult for the pick-up
conveyor 44 to
collect material from around the obstruction 19. Similarly, even where the
asphalt surface 18 is
only heated by the rejuvenating apparatus 10, it is difficult to break up and
pull away the heated
asphalt surface 18 from around the obstruction. The backhoe apparatus 200
facilitates removal
of such material from around the obstruction 19 and its movement to the
entrance 45 of the pick
up conveyor 44.
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In this respect, the present invention provides a method of effecting in-situ
rejuvenation of an
asphalt paved surface with an asphalt rejuvenating apparatus including a pick-
up conveyor 44
and a backhoe apparatus 200, wherein the asphalt paved surface includes a
solid object disposed
therein ahead of the pick-up conveyor 44, comprising the steps of: (i) heating
the asphalt paved
surface 18 to form heated asphalt, (ii) scarifying the heated asphalt to form
a scarified
intermediate, (iii) milling the scarified asphalt to form a milled
intermediate, (iv) adding
rejuvenating fluid to the milled intermediate to form a blended intermediate
46, wherein the
blended intermediate is deposited proximate the obstruction, and (v) moving
the blended
intermediate 46, from around and proximate to, or in the vicinity of, the
obstruction 19 and to
the entrance 45 to the pick-up conveyor 44 with the backhoe apparatus 200.
In one embodiment, the asphalt rejuvenating apparatus comprises a heater box
16, a raking
device 100, a main mill 36, and a pug mill 40. The heater box 16 heats the
asphalt paved surface
18 to form the heated asphalt. The raking device 100 scarifies the heated
asphalt to form a
scarified intermediate. The main mill 36 grinds the scarified intermediate to
form a milled
intermediate. The pug mill 40 adds rejuvenating fluid to the milled
intermediate and mixes the
milled intermediate with the rejuvenated fluid to form a blended intermediate
46. The blended
intermediate 46 is then carned or dragged by the backhoe apparatus 200 to the
entrance 45 of the
pick-up conveyor 44.
The backhoe apparatus 200 is useful in carrying or dragging blended
intermediate 46 from behind
an obstruction 19, where the obstruction 19 is disposed between the blended
intermediate 46 and
the pick-up conveyor 44. In one embodiment, the blended material is deposited
behind the
obstruction relative to the entrance 45 to the pick-up conveyor 44. The
backhoe apparatus is
configured to move laterally relative to the asphalt surface connecting the
blended intermediate
46 to the entrance 45 to the pick-up conveyor 44. In this respect, the backhoe
apparatus 200 is
rotatably mounted to the asphalt rejuvenating apparatus 10 about an axis
perpendicular to the
asphalt paved surface 18. The backhoe apparatus 200 is rotatably mounted to
the pick-up
conveyor 44. To further assist in transportation of the blended intermediate
46, the backhoe
apparatus 200 is configured to be retractable as well as capable of moving
vertically relative to
the asphalt paved surface 18.
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Figures 8 to 10 illustrate the path along which the blended material 46 is
moved by the backhoe
apparatus 200 from around or behind an obstruction 19. Each of the figures
illustrate the
obstruction 19 disposed in different positions relative to the entrance 45 of
the pick-up conveyor
44. Figure 8 illustrates a path along which the blended material 46 is carned
by backhoe
apparatus 200 by way of directional arrows 220a, 220b, 220c and 220d. In this
illustration, the
obstruction 19 is disposed directly along a centre line 230 of the entrance 45
to the pick-up
conveyor 44. Figure 9 illustrates the possible paths along which blended
intermediate 46 may
be carried by backhoe apparatus 200, when the obstruction 19 is disposed to
one side of the
centre line 230 of entrance 45 to pick-up conveyor 44, by way of directional
arrows 222a, 222b,
and 222c. Figure 10 illustrates paths along which blended intermediate 46 may
be carried by
backhoe apparatus 200 when the obstruction 19 is located along the other side
of centre line 230
of entrance 45 to pick-up conveyor 44, by way of a directional arrow 224a,
224b, and 224c.
In another embodiment, there is provided a method of effecting in-situ
rejuvenation of the asphalt
paved surface 18 with the asphalt rejuvenating apparatus including the pick-up
conveyor 44 and
a backhoe apparatus 200, wherein the asphalt paved surface 18 includes the
obstruction 19
disposed therein, comprising the steps of: (i) heating the asphalt paved
surface 18 to form heated
asphalt, (ii) scarifying the heated asphalt to form a scarified intermediate,
(iii) milling the
scarified asphalt to form a milled intermediate, and (iv) moving the milled
intermediate 46 to an
entrance 45 to the pick-up conveyor 44 with the backhoe apparatus 200.
Rejuvenating fluid may
be added prior to milling of the asphalt paved surface 18.
In another embodiment, backhoe apparatus 200 is used to scrape and pull the
heated asphalt in
the region proximate to, or in the vicinity of, the obstruction 19. In this
respect, there is also
provided a method of effecting in-situ rej uvenation of an asphalt paved
surface 18 with an asphalt
rejuvenating apparatus including the pick-up conveyor 44, and the backhoe
apparatus 200,
comprising the steps of: (i) heating the asphalt paved surface 18 to form
heated asphalt, (ii)
scraping and pulling the heated asphalt proximate to, or in the vicinity of,
the obstruction with
the backhoe apparatus 200, to form a first intermediate, (iii) moving the
first intermediate to the
entrance 45 to the pick-up conveyor with the backhoe apparatus 200.
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Although the disclosure describes and illustrates various embodiments of the
invention, it is to
be understood that the invention is not limited to these particular
embodiments. Variations and
modifications may occur to those skilled in the relevant art. For definition
of the invention,
reference is to be made to the appended claims.
