Road structure – process – or apparatus – Process – Providing expansion joint
Reexamination Certificate
2000-11-21
2002-12-10
Hartmann, Gary S. (Department: 3671)
Road structure, process, or apparatus
Process
Providing expansion joint
C404S075000
Reexamination Certificate
active
06491472
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the construction of airplane runway, and more particularly to processes of finishing slits of surface layers of runway, taxiway, apron, hangar, and the like.
BACKGROUND OF INVENTION
The conventional process of finishing slits of surface layers of the runway and the like is described and discussed hereinafter with reference to the accompanying
FIGS. 1-20
. The runway in question has a length of 3000 meters, a width of 60 meters, and a thickness of 30 centimeters.
As shown in
FIG. 1
, the runway is formed of a gradation layer A, and a surface layer
10
which is paved on the gradation layer A and is formed of pavement concrete (PC) or reinforced concrete (RC).
As shown in
FIG. 2
, the runway is provided on the gradation layer A with a plurality of first surface layer units
10
A, which are parallel to one another at an interval of six meters and are equal in length to the runway. The surface layer units
10
A are formed of pavement concrete or reinforced concrete.
As shown in
FIG. 3
, the runway surface layer
10
is further formed of a plurality of second surface layer units
10
B, which are paved side by side with the first surface layer units
10
A such that a second slit
17
is formed in the juncture of the first surface layer unit
10
A and the second surface layer unit
10
B.
As shown in
FIG. 4
, the surface layer
10
is provided with a longitudinally-oriected expansion slit
11
, which is formed by cutting in the juncture of the first surface layer unit
10
A and the second surface layer unit
10
B. The expansion slit
11
has a depth of 3 cm, and a width of 1 cm.
As shown in
FIG. 5A
, the runway surface layer
10
is provided with hundreds of guide slits
12
, which are arranged at a predetermined interval such that they are perpendicular to the length of the runway, The guide slits
12
are intended to prevent the formation of irregular cracks in the surface layer
10
.
As shown in
FIG. 5B
, each of the guide slits
12
is provided with a horizontally-oriented expansion slit
13
which has a depth of 3 cm and a width of 1 cm, thereby resultion in formation of a number of checkers
14
on the surface layer
10
, as shown in FIG.
6
. The checkers
14
are intended to prevent the surface layer
10
from being damaged by the effects of expansion and contraction of the surface layer
10
due to the climatic factors.
As shown in
FIGS. 7 and 8
, the longitudinal expansion slit
11
and the horizontal expansion slit
13
are provided with a polyethylene (PE) strip
15
and a polyurethane (PU) slit-filling agent
16
covering the PE strip
15
. The construction of the surface layer
10
is thus completed such that the runway is resistant to water.
The conventional process described above is also used to build taxiway, apron, hangar, and the like, The conventional process has several deficiencies, which are explicitly described hereinafter.
In light of the first surface layer units
10
A and the second surface layer units
10
B being constructed separately, there is formation of the second slit
17
in the juncture of the first surface layer unit
10
A and the second surface layer unit
10
B, as shown in
FIGS. 3
,
4
, and
7
. Upon completion of the guide slit
12
, a through slit
18
is formed in such a way that it extends from the bottom of the guide slit
12
toward the gradation layer A, as shown in FIGS,
5
A,
5
B, and
8
. The slit-filling agent
16
is coated on the inner walls of the longitudinal expansion slit
11
and the horizontal expansion slit
13
, without penetration into the small holes of the inner walls of the expansion slits
11
and
13
. As a result, the slit-filling agent
16
is apt to be stripped form the expansion slits
11
and
13
under the influence of the climatic changes, The slit-filling agent
16
is different in heat expansion coefficient from the first surface layer unit
10
A, the second surface layer unit
10
B, the pavement concrete, and the reinforced concrete. As a result, a water interstice
11
′ is formed between the longitudinal expansion slit
11
and the slit-filling agent
16
, as shown in FIG.
9
. Similarly, a water interstice
13
′ is formed between the horizontal expansion slit
13
and the slit-filling agent
16
, as shown is FIG.
10
. The water finds its way into the gradation layer A via the water interstice
11
′ and the second slit
17
, as shown in
FIGS. 7 and 9
. Similarly, the water finds its way into the gradation layer A via the water insterstice
13
′, the guide slit
12
and the through slit
18
, as shown in
FIGS. 8 and 10
. In light of the effect of the water erosion, A void A
1
is formed in the gradation layer A, as shown in FIG.
11
. The void A
1
weakens the structural strength of the area in the vicinity of the longitudinal expansion slit
11
. Such a weakened area of the surface layer
10
of the runway is apt to cave in when the surface layer
10
is exerted on by an external force of an airplane or heavy equipment, thereby resulting in formation of a pothole
19
in the surface layer
10
of the runway, as shown in FIG.
11
. It is conceivably unsafe for an airplane to land or take off on a runway having potholes. The only workably remedy to provide the gradation layer A of the runway with protection against the water erosion is to replace the slit-filling agent
16
periodically. The periodic replacement of the slit-filling agent
16
is not cost-effective and is apt to hinder the normal operation of the airport.
The rain water tends to accumulate in those checkers
14
which are located in the juncture of the longitudinal expansion slit
11
and the horizontal expansion slit
13
. As a result, the checkers
14
are susceptible to surface crack
14
′, as shown in FIG.
12
. The surface crack
14
′ will eventually become a pothole
19
, The conventional method of repairing the surface crack
14
′ involves a first step in which two slender slits
141
are formed by cutting along two longitudinal sides of the surface crack
14
′, as shown in FIG.
13
. Thereafter, the surface layer
10
located between the two slender slits
141
is removed to form a shallow trench
142
which has a width of 30 cm and a depth of 10 cm, as shown in FIG.
14
. As shown in
FIG. 15
, the shallow trench
142
is then filled with a filling material
20
, which is a mixture containing water, epoxy resin quartz sand, pavement concrete, or reinforced concrete, The filling material
20
is different in heat expansion coefficient from the surface layer
10
and is therefore vulnerable to being separated from the side walls and the bottom wall of the shallow trench
142
, thereby resulting in formation of a second process silt
21
between the filling material
20
and the shallow trench
142
, as shown in FIG.
16
. The water W enters from the second process slit
21
into the surface crack
14
′ which is located under the shallow trench
142
. Subsequently, the water W enters the gradation layer A from the surface crack
14
′. It is also likely that a gap
23
is formed between the bottom wall of the shallow trench
142
and the filling material
20
, as shown in FIG.
17
. This is due to the fact that the filling material
20
is exerted on by the expansion forces of the side walls of the shallow trench
142
. As a result, the filling material
20
is partially jutted out of the shallow trench
142
. The surface layer
10
of the runway is therefore rugged, In other words, the filling material
20
might become a culprit responsible for the flat tire.
In the event that the surface crack
14
′ is numerous, the surface layer
10
of the runway is replaced with a new surface layer. The process of paving a new surface layer involves a first step in which a thickness of 10 cm of the surface layer
10
is removed from the runway, so as to form an intermediate layer
10
′, as shown in FIG.
18
. The intermediate layer
10
′ is sprayed with a layer of asphalt, thereby resulting in
Chan Raymond Y.
David and Raymond Patent Group
Hartmann Gary S.
LandOfFree
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