Note: Descriptions are shown in the official language in which they were submitted.
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Reasphalting machine
The invention relates to a method for reasphalting a section of an asphalted
road consisting of a base of base material and an asphalt coating which may
comprise several layers of asphalt.
The invention also relates to a reasphalting machine for reasphalting a
section of an asphalted road consisting of a base of base material and an
asphalt coating which may comprise several asphalt layers, wherein the
reasphalting machine comprises
- a support frame which is supported by wheels,
- a cutting implement, with a substantially horizontal front edge for
loosening asphalt above the cutting implement when advancing the
reasphalting machine,
- a transport track for passing the loosened existing asphalt from the
cutting implement to a mixing chamber for mixing existing asphalt with
bitumen and possibly aggregate and solvents for the production of new
asphalt material, and
- an asphalt-laying device for adding the new asphalt material to the
road in order to form a new asphalt coating, the asphalt laying device is
located behind the cutting implement.
On account of wear, the formation of grooves due to car wheels, setting in
the base and the influence of water and temperature, asphalted roads have to
be reasphalted at intervals. In order to avoid an increase in the height of
the
road, the top layer of the asphalt coating in many cases is milled off before
new asphalt is applied.
Asphalt consists of bitumen, solvents and aggregate of varying size, usually
in the form of different rock materials of a size varying from stone dust to
crushed rock measuring between 10 and 20 mm. The quantitative ratio
between aggregates of different sizes is laid down in standards. Roads are
normally asphalted with asphalt which has a high percentage of large
aggregate, since such asphalt is more hard-wearing than asphalt which has a
high percentage of fine materials.
In this patent application asphalt should also be understood to include
similar
materials which are employed for road surfacing, particularly oil gravel.
AN1EIVDcD SHEET
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Milled-off asphalt can be recycled by heating it and mixing it with bitumen
and possibly aggregate and solvents, or the milled-off asphalt can be mixed
into the new asphalt material. During the milling process, however, a great
deal of the aggregate is crushed and ground into fine materials, and thus
there
is a limit to how much milled-off asphalt can be used in the new asphalt
material without the content of fine materials in the asphalt material
becoming so high as to compromise the wear resistance of the finished
asphalt coating. This complicates the production of the asphalt material,
making recycling of milled-off asphalt unprofitable. In many cases,
therefore, the milled-off asphalt is instead driven to a dump site. From the
environmental point of view, of course, this is undesirable.
Moreover, milling off asphalt is energy and time-consuming, and therefore
from an economic point of view it is desirable t.o avoid this milling process.
SE B 441 759 describes a reasphalting machine where asphalt which has
been scaled or milled off in advance is collected in a channel and fed into a
mixing chamber where it is mixed with new asphalt for subsequent
application to the road, directly from the open bottom of the mixing chamber.
SE B 447 586 describes a reasphalting machine where the existing asphalt
coating is heated by microwaves in the front edge of the machine. Shredding
bodies tear up the heated asphalt, whereupon the asphalt is passed up a
channel by means of a screw and into a mixing chamber, where it is mixed
with new asphalt. The finished asphalt is applied to the road through an
opening in the rear edge of the mixing chamber.
DE C2 3 739 294 describes a machine for producing a groove or a furrow in
an asphalt surface, where a knife or a cutting implement is forced in under
the asphalt surface by a hydraulic cylinder. A vibrator or rocking device
gives the knife an alternating twisting movement in the vertical direction,
with the result that the asphalt is forced up. Lateral edges ensure that the
furrow has uniform edges.
EP A1 0 324 491 describes a reasphalting machine where loose asphalt which
is loosened in advance by a scraping process is collected by a collector in
the
- front of the machine. The loose asphalt undergoes a cold process where
water-based solvents are added to it, whereupon it is laid out on the road
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again as a new asphalt surface.
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US A 3 472 554 describes a cutter wheel assembly for cutting asphalt
pavement and the like, comprising a cutter wheel arranged to be mounted as
a caster on the back of the blade of a road grader or like. A clean cut line
is
produced under direct visual guidance of the grader operator.
The object of the invention is to provide a method and a reasphalting
machine for reasphalting a section of an asphalted road, wherein existing
asphalt can be employed in new asphalt material without this leading to an
undesired high percentage of fine materials in the new asphalt material. The
object is further to avoid energy and time-consuming milling-off of existing
asphalt. A further object is to be able to employ the method for reasphalting
and the reasphalting machine both when only one or more layers of the
existing asphalt coating have to be removed before new asphalting, and when
the entire existing asphalt coating has to be removed before new asphalting.
The object is further to be able to repair and level the road's base in a
rational
manner before application of new asphalt material. A further object is to be
able to reinforce the road's base before the application of new asphalt
material. The object is further to be able to reasphalt the full width of a
traffic lane in the road without impeding traffic in adjacent lanes.
The objects are achieved according to the invention with a method and a
reasphalting machine of the type mentioned in the introduction, characterized
by the features which are indicated in the claims.
Thus the core of the invention consists in existing asphalt being loosened
from the road by the insertion of a cutting implement with a substantially
horizontal front edge under the existing asphalt, thus loosening it as a
whole.
This existing asphalt is mixed with bitumen and possibly aggregate and
solvents, thus producing a new asphalt material, which in turn is added to the
base for the formation of a new asphalt coating.
Asphalt coating may consist of one or more layers of asphalt, and according
to the invention either the entire asphalt coating or only one or more of
these
layers may be loosened by the cutting implement.
The invention will now be explained in more detail in connection with a
description of a specific embodiment, and with reference to the drawings, in
which:
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Fig. 1 is an elevational view of a reasphalting machine according to the
invention.
Fig. 2 is a top view of the reasphalting machine in fig. 1.
Fig. 3 is an elevational view of a cutting implement which is employed in the
invention, during loosening of an entire asphalt coating.
Fig. 4 is an elevational view of the cutting implement in fig. 3, used when
loosening one layer of an asphalt coating.
The same reference numerals are employed in all the figures.
Figs. 1 and 2 illustrate a reasphalting machine according to the invention for
reasphalting a section 2 of an asphalted road 1. In the illustrated embodiment
the section which has to be asphalted constitutes one traffic lane.
In order to present the inventive concept in the clearest possible way,
details
which are unimportant for the actual invention have been omitted. The
machine's various components are attached to a support frame 32 which in
turn is supported by wheels 28.
In order from the front, i.e. from the left in figures 1 and 2, can be seen
first a
lorry 20, which does not form part of the invention, and which will be
discussed in more detail later. Then follows an intake 22 for supply of new
asphalt material and new base material, which will also be discussed in more
detail later.
Behind the intake 22 there is provided a cutting implement 9 with a
substantially horizontal front edge 15 for loosening existing asphalt from the
road. As the reasphalting machine advances in the direction illustrated by the
arrow P1, the asphalt is loosened as a continuous layer or coating 5, which
will be discussed in more detail later, and is pressed slidingly up the
cutting
implement 9 to a breaking unit 12, illustrated as a wheel with four wings. By
means of the wheel's rotation the asphalt coating 5 is broken up into smaller
pieces, and falls down on to a transport track 17 in the form of a conveyor
belt, which passes the asphalt to a heating unit 13.
In the heating unit 13 the asphalt is heated by a combination of microwaves
and heat from diesel combustion. The electricity which is used in the
microwave heating is generated by diesel-driven electric units 31, placed on
r
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supports 33 in the machine's rear portion. At the same time surplus heat from
the diesel combustion is also used for heating the asphalt, thus achieving a
high energy utilisation. Alternatively, the asphalt pieces may be heated
directly by flames from diesel combustion.
5 From the heating unit 13 the hot asphalt is passed via a transporter 24 to a
mixing chamber 25, where it is mixed with bitumen from tank 27 supported
by a frame 48, thus producing a new asphalt material which can be employed
in asphalting the road. Depending on the kind of asphalt which requires to be
produced in the mixing chamber, aggregate and solvents may also be added.
As aggregate a base material may be used, which will be discussed in more
detail later, which is supplied via a transporter 26 from a storage tank 40.
Solvents may be added from a not shown solvent tank.
From the mixing chamber 25 the asphalt material is passed by means of a
transporter 46, illustrated as a conveyer belt, to an asphalt-laying device 41
in the rear edge of the machine, where the asphalt material is indicated by
reference numeral 10. The asphalt material is laid on the road in the known
manner, and the laid asphalt is rolled by a roller 34 to form a finished new
asphalt coating 11.
Fig. 3 illustrates the cutting implement 9 in closer detail, while
simultaneously illustrating the construction of the road 1 and the location of
the cutting implement relative thereto corresponding to figs. 1 and 2.
The road in fig. 3 consists at the bottom of underlying materials 19, which
may consist of coarse stones. On top of these underlying materials 19 the
road consists of a base 3 of base material 4, which may typically be stones
measuring 10 to 20 mm, and on top of this an asphalt coating 5.
The cutting implement 9 is composed of a substantially flat plate, extending
over the entire width w of the area which has to be reasphalted. As the
reasphalting machine advances in the direction P 1 the front edge 15 of the
cutting implement is disposed at a level between the asphalt coating 5 and the
base 3, and the cutting implement 9 is tilted in the direction backwards and
upwards. The front edge 15 of the cutting implement is forced in between the
asphalt coating 5 and the base 3, thus causing the asphalt coating 5 which is
located above the cutting implement to be loosened from the base 3 as a
whole, and pressed slidingly up the cutting implement 9. The upper portion
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of the cutting implement is rotatably attached to a bracket 42 by means of a
rotating joint 44, and the bracket 42 in turn is welded to the support frame
32. In its central area or lower portion the cutting implement 9 is connected
to a hydraulic cylinder 29, which is connected via a rotating joint 45 and a
bracket 43 to the support frame 32. By means of not shown measuring and
control devices the front edge 15 of the cutting implement can be adjusted by
means of the hydraulic cylinder 29 to the correct level between the asphalt
coating 5 and the base 3.
Fig. 3 also illustrates a cutting device 16 disposed in front of the cutting
implement 9, at the part of the cutting implement's outer edge which faces in
towards the middle of the roadway. The cutting device 16 is composed of a
wheel which by means of a not shown device is pressed so far down into the
roadway that along the centre line of the road a through-going groove 47 is
produced in the existing asphalt coating 5, see fig. 2. The reasphalting area
2
thereby obtains a uniform edge, which facilitates the laying of new asphalt
and ensures a smooth transition between the reasphalting area and the rest of
the roadway.
During the loosening and subsequent removal of the entire asphalt coating,
the base 3 is exposed, as illustrated in figs. 1 and 3. On account of setting
and the influence of water and temperature the base will often be uneven, and
may have cavities 14, see fig. 1. When reasphalting the road it is necessary
to
level out the base, and this is accomplished according to the invention with
scrapers, which in the illustrated embodiment are three in number and are
indicated by reference numerals 35, 36 and 37. The scrapers are tilted in a
zigzag pattern, and displaced relative to one another in the direction of the
reasphalting machine's width, see fig. 2. As the reasphalting machine
advances in the direction P1 the base is first levelled by the front scraper
35.
During levelling the front scraper simultaneously picks up existing base
material 4 (see fig. 1) and, due to its tilted position, the front scraper 35
passes the base material up towards one side of the reasphalting machine. At
the end of the front scraper 35 the base material 4 leaves the scraper and is
picked up by the middle scraper 36, which continues the levelling of the base
and passes the base material 4 out towards the other side of the reasphalting
machine, where it leaves the middle scraper 36. The rear scraper 37 picks up
the base material and completes the scrapers' levelling of the base.
AMENDEfl ~;i~r
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The reasphalting machine also includes a spreading box 3 8 located behind
the rear scraper 37, for laying out new base material 18. The new base
material 18 is added from the storage tank 40, which was mentioned in
connection with the heating unit 13. Cavities 14 in the base which have not
been filled by the levelling of the scrapers are filled with new base material
18 from the spreading box 38. The scrapers 35, 36 and 37 and the spreading
box 3 8 thereby provide a rational repair and levelling of the road's base
before application of new asphalt material. The spreading box 38 may also be
used for laying out a layer of new base material in order to reinforce the
road's base before the application of new asphalt material.
Behind the spreading box 38 there is located a compactor 39, which
compacts the base 3 and increases its firmness prior to asphalting with the
asphalt-laying device 41, which is located at the back of the machine.
The cutting implement 9, the scrapers 35, 36 and 37, the spreading box 38,
the compactor 39 and the asphalt-laying device 41 are vertically movable and
are controlled by not shown control devices. The spreading box and the
asphalt-laying device may also have capacity regulation.
The level as well as any unevenness in the existing asphalt coating and the
base, and the level of the new asphalt coating are measured by suitable
measuring equipment, such as vertically movable measuring wheels placed in
the front and rear edges of the machine and between the cutting implement 9
and the front scraper 35. For reading the wheels' vertical position, laser
technology may advantageously be employed. The read-off measured values
are used as the basis for control of the cutting implement, the scrapers, the
spreading box, the compactor and the asphalt-laying device in order to obtain
correct height of the cutting implement, application of the desired amount of
new base material, desired evenness and firmness of the base, thickness of
the new asphalt coating and levelness and height of the new asphalt coating's
surface.
As mentioned earlier, at the front edge of the machine there is an intake 22
for supply of new asphalt material and new base material. The intake 22 is in
the form of a carriage with a box or container, and receives when required a
supply of new asphalt material or new base material from a loading area 21
on the lorry 20. A transport track 23 in the form of a conveyor belt which is
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located above the cutting implement 9 passes the new asphalt material or the
new base material from the box or the container 22 to a rotatable transporter
30 located beside the storage tank 40. When new base material is supplied
the transporter 30 is directed towards the storage tank 40, and the new base
material, indicated by reference numeral 18, is passed down into the storage
tank. When new asphalt material is supplied the transporter is directed
towards the asphalt-laying device 41, as illustrated in fig. 2, and the new
asphalt material, indicated by reference numeral 10, is thereby passed to the
asphalt-laying device.
Fig. 4 illustrates the cutting implement 9 in use on a road where the asphalt
coating consists of several layers of asphalt, indicated by reference numerals
6, 7, 8, and where only the top asphalt layer 8 requires to be removed. As the
reasphalting machine advances the front edge 15 of the cutting implement is
here disposed at a level between the top asphalt layer 8 and the second top
asphalt layer 7. The adhesion between two asphalt layers is not so great as to
prevent the layers from sliding apart when the cutting implement 9 is forced
in between the layers, while at the same time the internal adhesion in each of
the layers is strong enough to hold the asphalt together. As the cutting
implement advances the top asphalt layer 8 is thereby loosened from the
second top asphalt layer 7 as a whole, and is pressed up the cutting
implement 9 in a substantially continuous layer. The scrapers, the spreading
box and the compactor can also be employed when the reasphalting machine
is used for this purpose if there are cavities in the underlying asphalt
layers 6,
7.
With the invention there are provided a method and a reasphalting machine
for reasphalting a section of an asphalted road, where existing asphalt is
used
in the new asphalt material without employing energy and time-consuming
milling. The aggregate in the existing asphalt is thereby not exposed to
crushing and grinding into fine materials as is the case with milling, and the
new asphalt material thereby does not acquire an undesired high percentage
of fine materials.
The area being reasphalted may have any desired width. In the illustrated
embodiment the area has a width corresponding to one traffic lane, and since
new asphalt material and new base material are supplied from the lorry
located in front of the reasphalting machine, the reasphalting machine
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according to the invention can be employed for reasphalting the full width of
a traffic lane of a road without impeding the traffic in adjacent lanes.
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