Note: Descriptions are shown in the official language in which they were submitted.
lil~893
The present invention relates generally to highway paving equip-
ment, and more specifically to equipment for laying a plurality of layers
of concrete simultaneously.
Certain aggregates are better than others for use in concrete
for forming highways and the like.
The aggregates used for such concrete should be of a high quality
material. In certain parts of the U.S.A. such high quality aggregates
are readily available, but in many parts of the United States the supply
of high quality aggregates is limited or nonexistent. Consequently, these
higher quality aggregates must be shipped in from wherever they are availa-
ble, thereby increasing the cost thereof considerably by virtue of suchtransportation costs.
Because of this shortage of high quality aggregates in many areas,
many people in the paving industry are advocating the use of a two layer
concrete pavement, the lower layer of which would be formed by a mixture of
primarily portland cement, water and locally avallable aggregates, while
the upper layer of the pavement which would be sub~ected to wear would be
formed of concrete with the usual high quality aggregate therein. The use
of a cheaper and more readily available aggregate forms a concrete commonly
referred to as "econocrete". It can easily be appreciated that there
would be a considerabIe savings in material and transportation costs if
such a composite pavement is used.
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8g3
One of the problems associated with using two layers of concrete
is that time and labor cost~ were increased because a first slip form
machine was used to place the "econocrete" layer, and a second machine
went over the "econocrete" layer and deposited the higher quality layer
of concrete. This problem has been overcome by the use of a machine and a
method provided by U.S. Patent No. 4,073,592 issued February 14, 1978 to
Godbersen, et. al.
Another problem associated with the use of multi-layered concrete
pavement is the one of insuring that the two layers stay bonded together.
This problem i8 solved by the use of the apparatus and method described in
the above identified U.S. Pàtent No. 4,073,592 which discloses laying two
or more layers of concrete simultaneously 80 that they will bond together
permanently. Since this bonding of the two layers is to insure that the
two layers do not come separated and become movable, one with respect to
the other, it is desirable to do anything economically feasible towards
assuring the achievement of this goal.
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893
An object of one broad aspect of this invention is
to provi,de an improved apparatus for laying a multi-layered
pavement.
An object of another aspect of this invention is to
provide an apparatus for positively connecting layers of concrete
pavement together for prevention relation relative movement bet-
ween the layers.
By one broad aspect of this invention, an apparatus is
provided for concurrently laying a multiple layered cementitious
pavement on a base surface, said apparatus having a normal
direction of movement and inc],uding: a movable frame; a first
s-trike-off means and being positi,oned generally trar.sversely of
the normal direction of movement of the frame for shaping the
top of the first cementitious composition; a second means attached
to the frame and specially adapted for receiving a second ceme3l-
titious composition and for depositing that second cementitious
composition on top of t-he first cementitious compositionj a second
strike-off means attached to the frame behind the second receiving
means and being positioned generally transversely to the normal
direc1,ion of movement of the frame for determining a top level
of the second cementitious compositionj t,he ,improvement compr;sing:
means disposed on the bottom of -the first strike-off means for
forming grooves in the top of the first cementitious composition
in a plastic condition, which grooves are then immediately filled
with the second cementitious composi1;on in a plastic condition to
form interlocking layers of cementitious material which dry to-
gether, thereby substantially preventing the first and second
cementitious coMpositions from moving with respect .o each oth~r
once the pavement is laid.
893
By another aspect of this invention, a method is pro-
vided for concurrently laying a multiple layered cementitious
pavement on a base surface by use of a single machine having a
normal direction of movement, said machine including a movable
frame; a first means attached to a front portion of said frame
and specially adapted for receiving a first cementitious compo-
sition; a first strike-off means and being positioned generally
transversely of the normal direction of movement of the frame
for shaping the top the first cementitious composition; a second
means a-ttached to the frame and specially adapted for receiving
a second cementitious composition and for depositing the second
cementitious composition on top of the first cementitious compo-
sition; a second strike-off means attached to the frame behind
the second receiving means and being positioned generally trans-
versely to the normal direction of movement of t-he frame for de-
termining a top level of the second composition; and means disposed
on the bottom of the first strike-off means for forming groooves
in the top of the first cementitious compositions, the method
comprising; depositing a first homogeni.ous cementitious composi-
tion in a plastic condition on the base surface in front of thefirst means for receiving the first composition; ]eveling the
first cementitious composition with the first strike-off means;
forming grooves in the top of the first cementitious composition;
depositing a second homogenious cemen-titious composition in a
plastic condition into the second means for receiving the second
cementitious composition and into the grooves in the first cemen-
tit;ous composition; leveling the second cementitious composition
by use of the second strike-off means; whereby all of the steps
of the method
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893
are performed simultaneously; and whereby the cementitious com-
positions are formed in-to interlocking layers which dr,y together,
thereby substantially preventing the first and second cementi-
tious compositions from moving with respect to each other once
the pavement is laid.
By a variant thereof, the first ceinentitious composi-
tion is formed of different material than the second cementitious
composition.
Thus, by one embodiment- of the present invention, a
machine is provided which is of a type for laying more than one
layer of cementitious pavement simultaneously on a base surface.
The m~chine includes a moveable frame. A first receiving struc-
ture is attached to the front of the frame for receiving a first
cementitious composition and a first strike-off mechallism is
positioned behind such receiving structure for shaping the top
of the first cementitious composition. The first strike-off
mechanism has a cross-sectional shape which causes a non-planar
surface, e.g. grooves to be formed on the top to the first
cementitious composition (while it is in the plastic state),
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893
A second receivlng structure is attached to the frame behind the first re-
ceiving structure for receiving and depositing the second cementitious
composition on top of the first cementitioug composition and a second
strike-off mechanism is positioned for shaping the top level of the second
cementitious composition. When the second cementitious composition (also
in the plastic state) is placed on top of it there will be an interlocking
effect between the two layers of cementitious compositions so as to insure
that the layers will not move with respect to each.
In the accompanying drawings,
Figure 1 is a side elevational cross sectional view of a paving
machine constructed in accordance with one aspect of the present invention;
Figure 2 is a partial cross sectional view taken along line 2-2
of Figure l;
Figure 3 i8 a partial perspective view of the under side of the
groove forming mechanism of the apparatus of an aspect of the present in-
vention;
Figure 4 is a partial enlarged cross-sectional view taken along
line 4-4 of Figure 3;
Figure 5 is a view of the botton layer of concrete formed in
accordance with apparatus of an aspect of this invention; and
Figure 6 is a cross-sectional view taken along line 6-6 of
Figure 1.
893
Referring now to the drawing wherein like reference numerals
designate identical or corresponding parts throughout the several views,
Figure 1 shows a concrete paving machine generally indicated at 10 having a
first receiving chamber 11 on the front end thereof for receiving a first
cementitious material 12 in a plastic condition, and a second receiving
hopper 13 for receiving a second cementitious material 14, which material,
14, is also in a plastic condition for being shaped by use of slip forming
equipment. The main part of this machine is of a conventional design and
can be substantially the same as that shown in the aforesaid U.S. Patent
10 No. 4,073,592 to Godbersen, et. al.
A first vibrator 16 is attached to the front portion of the
first material receiving structure 11 by means of a clamping structure 17.
A hydraulic cylinder 18 is pivotally attached to the framework 19 of
the machine 10 at one end 21 thereof. The other end 22 of the hydraulic
cylinder 18 i8 pivotally attached to a lever 23, which attaches to the
structure 17, which mounting 6tructure 17 is disclosed more fully in the
above mentioned U.S. Patent. The hydraulic cylinder 18 and its associated
structure can then ~e used to pivot the vibrator structure 16 to deeper
or shallower levels within the first composltion 12 as needed. The vibra-
tor 16 is, of course, for the purpose of causing the material 12 to settleand to eliminate the voids or bubbles therein which would otherwise be
present.
893
A second vibrator or plurality of vibrators 24 is disposed in
the second hopper 13 for the purpose of vibrating the material 14 within
the hopper 13 to cause it to settle and remove all voids or bubbles as
with the vibrator 16. Control structures 26, 27 and 28 are also associa-
ted with the vibrators 24 and are identical in function to the elements
17, 18, 23 respectively of the first receiving structure 11 and vibrators
1~.
Also disposed within the hoppers 11 and 13 are auger assemblies
29 and 31 respectively. These auger assemblies 29 and 31 serve to spread
out the material within each respective hopper 11 and 13 and keep this
material moving forwart. These augers 29 and 31 are, of course, constantly
rotating when the machine i~ in operation.
A tamping assembly 32 is also disposed within the second hopper
13 and is constantly movlng vertically in a reciprocal fashion in order to
help level off the second composition 14 and to be sure that adequate
material flows under the finishing plate 33.
Referring now to the most important feature of the apparatus of
an aspect of this invention, it is noted that a striXe-off mechanism 34
is ateached to the side-plate framework 19 by means of a pair of nut and
bolt assemblies 35 which extend through openings in the framework 19 and
through slots 36 in the ends of gtrike-off plate 34. Thi~ member 34 ex-
tends completely across the machine from the side plate 1~ on one side
thereon to an identical sideplate 19 on the other side of the machine 10.
The bottom of the strike-off mechani~m 34 has substantially flat portions
37 and a pluraltiy of ribg 38 evenly disposed between the flat portion~
37.
893
In operation, a "ready-mix" truck having a spout 39 dumps a
first "econocrete" material 12 in front of the first material receiving
structure 11 and between the side plates 40 of the slip forming machine lO.
At the same time, a second "ready-mix" truck dumps a second concrete mater-
ial 14 into the second hopper 13 out of a spout 41. It is to be understood
that normally this second material 14 would be a concrete material in a
plastic condition which has high quality aggregates therein. This dumping
of the materials 12 and 14 into the material receiving chambers 11 and 13
would occur periodically as the machine continues to move in the forward
direction as indicated by the arrow 42 in Figure 1.
As the machine continues to move, the vibrating structure 16
settles the "econocrete" materlal 12, taking the bubbles and voids out of
this layer, while the auger 29 tends to level out such material 12 and
keep it moving forwardly. At the same time, the first strike-off mechan-
ism 34 operates to strike off the material 12 at the level and to the con-
figuration shown in Figure 5, whereby the material 12 is formed with a
plurality of grooves 43 (Fig. 5) therein. At the same time the second
layer of material 14 is being laid on top of the first material 12. While
the vibrator 24 is causing the bubble~ and voids to be dissipated from the
material 14 within the opper 13, the auger 31 is distributing the material
across the hopper 13, keeping this material moving forwardly ahead of the
auger 31 and the tampin~ bar 32 is operating to level off the material
14 and assure that the material is pressed down into the grooves 43 and is
evenly distributed and packed under the finishing plate 33.
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