Patent Grant
7059800
The present invention is related generally to methods of reinforcing and waterproofing paved surfaces such as roads and parking lots, and more particularly to a method which includes the use of a reinforcement mat.
Paved surfaces such as roads and parking lots are commonly constructed with a top surface layer of asphalt paving material. Over a period of time, the paved surface usually deteriorates due to the effects of traffic, temperature cycles, and other environmental causes. Cracks develop in the paved surface, and the cracks can spread and cause further deterioration. Water can penetrate the paved surface by flowing into the cracks, causing further damage.
Damaged paved surfaces are usually repaired by applying a new surface layer of paving material over the damaged portions or over the entire paved surface. After a paved surface having cracks is resurfaced, many times the new surface layer cracks directly over the cracks in the old surface. This is known as “reflective cracking.” One way to address this problem is to make the new surface layer thicker, but this is not very effective.
Consequently, various reinforcement materials and methods have been tried for preventing or repairing cracks and other deterioration in paved surfaces. One commercial product (an example of which is Petromat® available from BP Amoco) is a reinforcement mat constructed from nonwoven needle-punched polypropylene fibers. The polypropylene mat is applied over a tack coat of asphalt, and then a surface layer of paving material is applied over the mat. The paving material is heated prior to its application over the mat. Unfortunately, the polypropylene mat tends to melt and/or shrink when it is exposed to the hot paving material, which detracts from its ability to provide reinforcement and waterproofing. Additionally, if the tack coat is applied at too high a temperature, the polypropylene mat may likewise shrink or melt.
Various patents describe reinforcement materials and methods of reinforcing paved surfaces. For example, U.S. Pat. No. 2,115,667 to Ellis discloses reinforcing an asphalt road with a reinforcing agent made from woven glass. A woven reinforcement material is usually less porous than a nonwoven material. This impedes the ability of the asphalt to penetrate the reinforcement material to create a strong paved surface. A woven material is also usually more expensive to manufacture than a nonwoven material.
U.S. Pat. No. 4,637,946 to Shah et al. discloses a road repair membrane comprising a glass fiber mat impregnated with a blend of asphalt, block copolymer, and mineral filler. An impregnated mat would not be very effective in soaking up asphalt to create a strong bond with the road. A weakly bonded mat could delaminate from the asphalt layers, enabling the road surface to come apart.
U.S. Pat. No. 6,235,136 to Kittson et al. discloses a water-resistant mastic membrane. The membrane comprises a carrier layer and a grid of glass fibers, both embedded in molten mastic material. The carrier layer is designed to provide only limited performance to the mastic membrane, and can be destroyed, or melted, by the molten mastic material. The membrane is bulky, having a thickness of 50 mm to 150 mm, and consists primarily of mastic material.
In view of the above, it would be desirable to provide an improved method of reinforcing and waterproofing a paved surface, including a method of repairing a defect such as a crack in the paved surface.
The above object as well as others not specifically enumerated are achieved by a method of reinforcing and waterproofing a paved surface according to the invention. Initially, a layer of liquefied asphalt is applied on a paved surface. A reinforcement mat is then applied over the paved surface. The reinforcement mat includes a first layer comprising a nonwoven mat produced from fibers selected from the group consisting of mineral fibers, polymer fibers, and mixtures thereof. The reinforcement mat also includes a second layer of mineral fibers attached to the first layer. The liquefied asphalt penetrates and soaks the reinforcement mat to form a water barrier. A layer of paving material is then applied over the reinforcement mat. The first layer and the second layer of the reinforcement mat are attached to each other by any one of sewing, knitting, needling, heat treating, and adhering with an adhesive, or combinations thereof.
In one embodiment of the method, the reinforcement mat is applied to the paved surface after the liquefied asphalt is applied to the paved surface.
In another embodiment of the method the reinforcement mat is applied to the paved surface before the liquefied asphalt is applied to the paved surface.
In another embodiment of the method, the second layer of the reinforcement mat comprises continuous strands of glass fiber. The strands of glass fiber are oriented along one direction and are substantially parallel to one another.
In another embodiment of the method, the second layer of the reinforcement mat comprises a randomly-oriented continuous-strand glass fiber mat.
In another embodiment of the method, the second layer of the reinforcement mat comprises randomly-oriented chopped stands of glass fiber.
Another embodiment of the method relates to repairing an elongated crack in a paved surface. A reinforcement mat is applied over the crack by securing the reinforcement mat to the paved surface on one side of the crack and leaving the reinforcement mat unsecured to the paved surface on the opposite side of the crack. In a preferred embodiment of the repair method, the reinforcement mat includes a first layer comprising a nonwoven mat produced from fibers selected from the group consisting of mineral fibers, polymer fibers, and mixtures thereof. The reinforcement mat also includes a second layer of mineral fibers attached to the first layer. A layer of paving material is then applied over the reinforcement mat. The first layer and the second layer of the reinforcement mat are attached to each other by any one of sewing, knitting, needling, heat treating, and adhering with an adhesive, or combinations thereof.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.
The present invention relates to an improved method of reinforcing and waterproofing a paved surface such as a road, a parking lot, or any other type of paved surface. The method can be used in the construction of a new paved surface, in the rejuvenation of an existing paved surface, or to repair a crack, pothole, or other defect in an existing paved surface.
Referring now to the drawings,
The layer of liquefied asphalt 12 can be applied in any amount which is suitable for penetrating and soaking the reinforcement mat 14, described below. Preferably, the liquefied asphalt is applied at a rate within a range of from about 0.1 gallon/square yard (0.32 liter/square meter) to about 0.5 gallon/square yard (1.58 liter/square meter), the optimum rate depending on the weight of the reinforcement mat. The liquefied asphalt can be applied by any suitable method, such as by spraying it as a layer or by pouring and spreading it into a layer.
A second step of the method is to apply the reinforcement mat 14 over the liquefied asphalt 12, while the liquefied asphalt is still in the fluid condition. The reinforcement mat 14 is sufficiently porous such that the liquefied asphalt penetrates and soaks the reinforcement mat 14. In the embodiment shown, the layer of liquefied asphalt 12 includes a bottom portion 16 below the reinforcement mat 14 and a top portion 18 which saturates the reinforcement mat 14. However, the liquefied asphalt could also be located entirely inside the reinforcement mat after it is applied. Preferably, the reinforcement mat can absorb at least about 0.1 gallon/square yard (0.32 liter/square meter) of the liquefied asphalt.
A sufficient amount of liquefied asphalt 12 is applied, and the reinforcement mat 14 absorbs enough liquefied asphalt, to form a strong bond with the paved surface 10 and with the layer of paving material 20, described below. The reinforcement mat 14 also forms a water barrier that prevents water from penetrating into the paved surface from above. Preferably, the reinforcement mat 14 is substantially completely saturated with the liquefied asphalt, such that the liquefied asphalt penetrates from a bottom surface 22 to a top surface 24 of the reinforcement mat 14.
As shown in
In a first embodiment, the first layer 30 of the reinforcement mat 14 is made of glass fibers, and has a width w, as shown in
A first embodiment of the second layer is generally shown at 32 in
Adjacent parallel strands 34 can be spaced at any desired distance relative to one another. Preferably, the strands 34 are spaced within the range of about 0.5 to about 12 strands per inch of width w (19.7 to 472 strands/meter of width w) of the first layer 30. More preferably, the strands 34 are spaced at about 2.0 strands per inch of width w (78.8 strands/meter of width w) of the first layer 30.
Each bundle 34 can contain any desired amount of filaments of glass fibers. The strands 34 preferably have a yield within the range of from about 100 to about 1000 yards per pound (202 to 2020 meters/kilogram) of glass, which is equivalent to a linear density within the range of from about 4960 tex to about 496 tex. More preferably, the strands 34 have a yield within the range of from about 200 to about 450 yards per pound (403 to 907 meters/kilogram) of glass which is equivalent to a linear density within the range of from about 2480 tex to about 1100 tex. Additionally, the second layer 32 preferably has a basis weight within the range of from about 0.5 to about 15 ounces per square yard (17 to 512 grams/square meter) of reinforcement mat 14. More preferably, the second layer 32 has a basis weight within the range of from about 4.5 to about 6.5 ounces per square yard (153 to 220 grams/square meter) of reinforcement mat 14.
The strands 34 comprising the second layer 32 can be attached to the first layer 30 by any desired method. Knitting, as shown in
A second embodiment of the reinforcement mat is generally shown at 14′ in
The second layer 36 can be attached to the first layer 30 by any desired method. Knitting is a preferred method of attaching the second layer 36 to the first layer 30, as described above for attaching the second layer 32 to the first layer 30. As shown in
A third embodiment of the reinforcement mat is generally shown at 14″ in
The second layer 40 can have any desired basis weight. Preferably, the second layer 40 has a has a basis weight within the range of from about 0.5 to about 15 ounces per square yard (17 to 512 grams/square meter) of reinforcement mat 14. More preferably, the second layer 40 has a basis weight within the range of from about 5.0 to about 8.0 ounces per square yard (171 to 273 grams/square meter) of reinforcement mat 14. The second layer 40 can be attached to the first layer 30 by any desired method. Knitting is a preferred method of attaching the second layer 40 to the first layer 30, as described above for attaching the second layer 32 and 36 to the first layer 30. As shown in
The reinforcement mat 14, 14′, and 14″ can be wrapped in a continuous roll, although a continuous roll is not required. Preferably, such a continuous roll has a width within a range of from about 5 feet (1.52 meters) to about 20 feet (6.1 meters). The continuous roll may also have any desired width. The reinforcement mat 14, 14′, and 14″ is applied over the liquefied asphalt by unrolling the reinforcement mat 14, 14′, and 14″ from the roll onto the liquefied asphalt.
The liquefied asphalt is allowed to become firm, or at least partially solidify, at some time after the application of the reinforcement mat. Usually, the liquefied asphalt is allowed to become firm before the application of the paving material described below. For example, molten asphalt can be allowed to become firm by cooling, asphalt emulsion can be allowed to become firm by the evaporation of water, and cutback asphalt can be allowed to become firm by the evaporation of solvent. The open porosity of the first layer 30 of the reinforcement mat 14 facilitates the evaporation of water or solvent.
A third step of the method is to apply a layer of paving material 20 over the reinforcement mat 14, 14′, and 14″. The paving material 20 can be any material suitable for providing a top surface layer of a paved surface, such as an asphalt paving material, typically a mixture of asphalt 26 and aggregate 28, or a concrete paving material. The paving material is usually applied in a heated condition, and then allowed to cool. When the heated paving material is applied over the reinforcement mat the heat of the mix partially liquefies the asphalt in the reinforcement layer, drawing it up into the mat, and forming a monolithic waterproof bond with the overlying pavement layer. It is during this heating step (that is unavoidable when placing an asphalt paving mixture over the mat) that damage from melting and shrinking can occur with polypropylene mats.
When the reinforcement of the paved surface is completed, the penetration of the reinforcement mat by the liquefied asphalt 12 (now at least partially solidified) forms a strong bond between the reinforcement mat 14, 14′, and 14″, the asphalt 12, the paved surface 10, and the layer of paving material 20. This creates a strong, monolithic paved surface structure that is very resistant to damage. The high tensile and mechanical strength of the reinforcement mat 14, 14′, and 14″ provides mechanical reinforcement to the paved surface. Additionally, the penetration of the reinforcement mat by the asphalt forms a water barrier or waterproof membrane that prevents water from penetrating into the paved surface from above and causing damage.
In a fourth embodiment of the invention (not illustrated), the method comprises pavement of a non-paved surface by applying the liquefied asphalt on a prepared unpaved surface, applying the reinforcement mat over the liquefied asphalt and the prepared unpaved surface, and applying the paving material over the reinforcement mat 14, 14′, and 14″.
As mentioned above, the method of the invention can be used in the construction of a new paved surface, in the rejuvenation of an existing paved surface, or to repair cracks, potholes or other defects in an existing paved surface. When repairing a defect in a paved surface, a first step of the method is to apply a layer of liquefied asphalt on a paved surface having a defect. When the defect is a crack in the paved surface, the liquefied asphalt may be applied over the crack without initial preparation of the crack, or alternatively the crack may be filled with an appropriate crack filler such as those meeting the requirements of ASTM D-3405 or D-1190 or other suitable material. When the defect is a pothole in the paved surface, typically the pothole is initially filled with a material conventionally used for filling potholes, such as an asphalt paving material. Then the liquefied asphalt is applied over the filled pothole. Badly broken or rough pavement may require milling or placement of a leveling course before application of the liquefied asphalt. The reinforcement mat is then applied over the liquefied asphalt and the defect. Finally, a layer of paving material is applied over the reinforcement mat and the defect. When the repair is completed, the reinforcement mat forms a strong bond with the paved surface and holds the paved surface around the defect together. The reinforcement mat prevents water from penetrating into the defect from above and causing further damage.
In a fifth embodiment, the invention relates to a method of repairing a crack in a paved surface.
In this repair method, a desired reinforcement mat is applied over the crack 42. Preferably, the reinforcement mat 14 is used. However, any desired reinforcement mat, such as reinforcement mat 14′ and 14″ may also be used. Unlike the embodiments of the invention described above, in this repair method it is preferred that the reinforcement mat 14 is saturated with asphalt before it is applied to a road surface. The reinforcement mat 14 is secured to the first surface portion 44 of the paved surface 41 on the one side of the crack 42, but the reinforcement mat 14 is left unsecured to the second surface portion 46 of the paved surface 41 on the opposite side of the crack 42.
Then, a layer of paving material 20 is applied over the reinforcement mat 14. Securing the reinforcement mat 14 to the paved surface 41 on only one side of the crack 42 reduces the occurrence of reflective cracking by leaving a slip plane or energy dissipation area 48 between the reinforcement mat 14 and the second surface portion 46 of the paved surface 41. The slip plane 48 is defined as the area where a bottom surface of the reinforcement mat 14 contacts the paved surface 41. As the paved surface 41 surrounding the crack 42 is caused to move over time, the slip plane 48 allows the second surface portion 46 to move relative to the reinforcement mat 14 without the movement of the second surface portion 46 being reflected to the newly applied layer of paving material 20 and thereby creating a crack in the paving material 20.
The reinforcement mat can be secured to the paved surface on one side of the crack by any suitable method. In the embodiment shown in
In another embodiment (not shown), the adhesive is first applied to the reinforcement mat, and the reinforcement mat having the adhesive is then applied to the paved surface. In another embodiment (not shown), the reinforcement mat is secured to the paved surface by first applying a pressure sensitive adhesive to the reinforcement mat, and then pressing the reinforcement mat against the paved surface. In a further embodiment (not shown), the reinforcement mat is secured to the paved surface by first applying a self-activated adhesive to the reinforcement mat, and applying the reinforcement mat to the paved surface in a manner which activates the adhesive. For example, the self-activated adhesive may be a heat-activated adhesive which is activated when the layer of heated paving material is applied over the reinforcement mat. Alternatively, the reinforcement mat may comprise other known materials adhered to a single side of the crack.
As described in the paper entitled “A study of grid reinforced asphalt to combat reflection cracking,” by S. F. Brown et al., the crack-causing strain in an asphalt road surface is generally perpendicular or transverse to a crack formed in a road surface. Surprisingly, it has been discovered that by attaching the second layer 32 having the strands 34 parallel to the direction of vehicular travel, and positioning the strands 34 transverse to an elongated crack to be repaired, the occurrence of reflective cracking is substantially eliminated. As is known, cracks in road surfaces are often not elongated, are often irregularly shaped, and can extend in multiple directions. It has also been discovered that when the reinforcement mat 14′ and 14″, formed by attaching the second layers 36 and 40, respectively, to the first layer 30, is used to repair such an irregular crack, the occurrence of reflective cracking is substantially reduced.
The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope. For example, while the method of the invention has been illustrated in terms of reinforcing a new or rejuvenated paved surface, and repairing a crack in a paved surface, the method can also be used for repairing other defects such as potholes in paved surfaces. The drawings show a particular type and size of reinforcement mat, but other types and sizes of reinforcement mat can also be used. The drawings also show particular types and amounts of liquefied asphalt and paving material, but it is recognized that other types and amounts of liquefied asphalt and paving material can be used in the invention.
This application is a continuation-in-part of U.S. application Ser. No. 09/795,774, filed Feb. 28, 2001 now U.S. Pat. No. 6,648,547.
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| Number | Date | Country | |
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 09795774 | Feb 2001 | US |
| Child | 10188447 | US |
