PAVING MACHINE MEMBRANE DISPENSER

Abstract

The present invention is directed to an improved design and improved method of installation of stress absorbing membrane interlayers, commonly known as SAMIs, used for strengthening and waterproofing asphalt pavements in road or highway surfacing operations. By a novel method of modifying a standard paving machine the present invention makes it easier and more convenient to install SAMI membranes beneath a layer of new asphalt pavement, thus providing greater resistance to pavement cracking resulting in lower overall maintenance costs.

Claims

1. Modifications made to an asphalt paving machine which modifications consists of one or a plurality of mounted membrane dispensing shafts which said shafts can hold and allow the dispensing of a pavement reinforcing membrane continuously beneath a paving machine as it moves forward.

2. Membrane dispensing shafts in accordance with claim 1, wherein the said shafts are mounted on the front, or leading, portion of the paving machine or may also be mounted on the sides or center area of the said paving machine.

3. Membrane dispensing shafts in accordance with claim 2, wherein the said shafts are positioned such that they can allow dispensing of the said membrane in multiple strips to cover the center width between the machine's two tracks, and concurrently to cover the area beneath each of the machines two support tracks, and concurrently to cover the lateral area on the outer side of each of the machines two tracks, with or without the side edges of each membrane overlapping each adjacent membrane edge.

4. Membrane dispensing shafts in accordance with claim 3, where the shafts are positioned in a manner so that the edges of the said pavement reinforcing membrane strips dispensed from each shaft will overlap the edge of each adjacent dispensed membrane strip.

5. A Novel Method of asphalt paving whereby an asphalt paving machine with special membrane dispensing can continuously dispense a pavement reinforcing membrane onto a surface and concurrently dispense hot paving mix onto the said membrane as it moves forward.

6. A Novel pavement reinforcing membrane supplied as rolls and produced by hot-coating and sand surfacing both faces of a non-woven polymer fiber reinforcement sheet with an elastomeric modified asphalt bitumen coating which is formulated to have a heat-activated bonding surface.

7. A Novel pavement reinforcing membrane in accordance with claim 6, wherein the elastomeric modified asphalt bitumen coating contains the elastomeric Styrene Butadiene Styrene polymer modifier commonly known as SBS polymer.

8. Elastomeric modified asphalt bitumen coating in accordance with claim 7, wherein the said polymer modifier may be a Styrene Isoprene Styrene polymer, commonly known as SIS, alone or combined with an SBS polymer, or otherwise suitable polymers.

9. A novel pavement reinforcing membrane according to claim 8, wherein the said elastomeric asphalt coating may contain polymer modifier percentages ranging from 0% to 25% with a preferred total percentage of 10%.

10. A novel pavement reinforcing membrane according to claim 9 wherein, the non-woven polymer reinforcement sheet may be made of polyester fibers.

11. A novel pavement reinforcing membrane according to claim 10, wherein the non-woven polymer reinforcement sheet may be made of other suitable polymer fibers such as polypropylene, or a combination of other suitable fibers.

12. A novel pavement reinforcing membrane in accordance with claim 9, wherein the preferred asphalt bitumen utilized to blend with polymer modifier to coat the membrane is a standard paving grade of asphalt bitumen commonly known as 80/100 penetration grade, however other penetration or roofing grades of asphalt bitumen may be utilized also with or without added tackifying agents.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 shows a front view of the first example paving machine in which center membrane dispensing shaft 001, is shown, and under-track dispensing shafts 002 and 003 are shown, and side membrane dispensing shafts, 004 and 005 are shown.

[0019] FIG. 2 shows a side view of the first example paving machine in which side membrane dispensing shafts 003, and 005 are shown, and mounted rolls of membrane 011 are shown.

[0020] FIG. 3 shows a top plan view of the first example paving machine, 008, in which front center membrane dispensing shaft 001, under-track dispensing shafts 002 and 003, and side dispensing shafts 004 and 005 are shown and a schematic view of dispensed full width membrane, 006, beneath a pavement layer, 007, is presented.

[0021] FIG. 4 shows a detail of a membrane dispensing shaft, 007, with support hub 010.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0022] One preferred aspect of the present invention is to provide modifications to a typical asphalt paving machine which modifications would enable the said machine to dispense a stress absorbing membrane interlayer, or SAMI, beneath itself as it moves forward. The said modifications would preferably consist of a multiple number of membrane dispensing shafts attached to the lower front and each side of the said machine. The said membrane dispensing shafts are designed to hold wound-up rolls of a heat-bondable SAMI membrane and continuously allow dispensing of the said membrane onto the road bed beneath the said paving machine and beneath concurrently dispensed hot pavement mix as it moves forward.

[0023] The said membrane dispensing shafts shall be preferably made of round metal tubing having an outer diameter of about 62 mm. (2.5 inches). The lengths of the said dispensing shafts would about 1.3 m (4 ft.) but may be varied to suit their mounting positions. The preferred positioning of the said dispensing shafts would be such to dispense the membrane in adjacent separate strips to cover the width of the lane being paved. Retaining pins would be inserted through holes in the said dispensing shafts in order to hold the rolls of membrane in place as they unwind.

[0024] Preferably the center membrane strip mounted on shaft 001 on the drawing herein, dispensed at the front of the machine would cover a portion of the space between the paving machine supporting tracks which space is typically about 60 inches in width. Preferably separate strips of membrane mounted on shafts 002 and 003 herein, would be dispensed beneath each of the machine's tracks and be wider than the said tracks to overlap each edge of the said center strip, at 001. And preferably each of the two side strips of membrane, mounted on shafts labelled as 004 and 005 herein, would be dispensed on the outer side of each track to cover the required lane width of about 4.5 meters or 15 ft. Preferably the edge of each said strip of membrane would overlap the adjacent membrane strip by about 3 inches or greater. However alternatively the membrane edges may be positioned to not overlap each other. The hot pavement mix concurrently being dispensed and spread by the said paving machine would preferably overlay and cover the said membrane strips, transfer heat to them, and heat-activate their upper and lower adhesive surfaces to facilitate bonding of the said membrane.

[0025] By dispensing separate said membrane strips beneath each of the paving machine's support tracks, any distortion or wrinkling of the membrane that the tracks may cause during forward motion will be limited to those two strips only and not affect the full width of the membrane as might otherwise occur.

[0026] A second aspect of the present invention is to provide a novel method of paving whereby a mechanically altered asphalt paving machine can be operated to dispense a Stress Absorbing Membrane Interlayer or SAMI beneath itself as it moves forward while concurrently dispensing a layer of hot pavement mix over the said membrane. As in the normal asphalt paving procedure hot asphalt paving material is intermittently delivered by a dump truck or other means into the hopper of the paving machine, thence conveyed towards the rear of the machine to a screed area and dispensed onto the road surface in a thickness and width controlled by the screed. With the present invention, the hot asphalt would instead end up on the top surface of a concurrently dispensed pavement membrane beneath the paving machine and be screeded to a desired thickness, for subsequent roller compaction.

[0027] A third aspect of the present invention is to provide a novel SAMI membrane in wound-up roll form, being about 2.5 mm. ( 3/32 in.) thick and about 1 meter wide (40 in.), which is comprised of a non-woven polymer fabric coated with a heat-bondable elastomeric modified asphalt bitumen coating and mineral sand surfacing. Bonding of this membrane in place beneath hot pavement can occur due to the heat sensitive adhesive coating on the membrane becoming tackified by heat transfer from overlain hot pavement.

[0028] Currently used SAMI membranes must be pre-bonded in place with a hot-sprayed asphalt adhesive or have to be made to be self-adhesive with a removeable release layer so they can be bonded in place prior to paving over them. This requires the added labor and cost of spraying hot asphalt or removing and disposing of a costly release material. The advantage of the novel SAMI membrane of the present invention is that this said membrane can be dispensed by a suitably modified paving machine and heat-bonded in place with lower overall cost.

[0029] The foregoing descriptions and illustrations should not be considered to limit the scope of this invention. Numerous modifications and changes may become evident to those skilled in the art, and accordingly all suitable modifications and equivalence are considered to fall within the scope of the invention as defined by the claims and descriptions stated herein.

[0030] The following patent citations are listed herein for reference purposes only, as there is no noted conflict with the present invention described on the pages herein.