PAVEMENT LIFE EXTENSION PRODUCT AND METHOD

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a pavement life extension method that combines a material, repair methods and equipment to accomplish the overall goal of extending the useful service life of different types of transportation and vehicular pavement.

2. Background

Pavement overlay techniques are known. Some techniques rely on tar and asphaltic combinations, others rely on cement and modified cement mixtures. In the case where systems use non-asphaltic combinations to overlay pavements, the polymer modified material that is used typically requires water to the extent it dilutes the latex emulsion beyond its design limits thereby severely limiting or destroying the latex's binding and adhesive qualities. Another known product uses a cement/sand blend with too much cement. This product blends two parts 80 to 100 mesh mason sand with one part Type I Portland cement. This blend is far too rich in cement which in turn bleeds lime for an extended period of time and is also far too brittle (low plasticity) due to the large quantity of cement and not enough aggregate (sand). Other systems use equipment that is not proven in the marketplace or that is specifically designed for asphalt/petroleum based products. This renders a finished product that is aesthetically unacceptable and physically unstable.

Examples of past polymer composition pavement overlays:

U.S. Pat. No. 5,244,304 Is directed to a paving composition including a cement binder, a dispersible latex polymer binder and a mineral aggregate filler such as sand.

U.S. Pat. No. 4,430,463 discloses a flexible acrylic polymer Portland cement coating composition having unusual shear bond (adhesive) characteristics and unusually high abrasion and heat resistance which incorporates sand, Portland cement, acrylic polymer, propylene glycol and a defoamer.

U.S. Pat. No. 4,714,507 sets forth a surface coating agent and method for applying the coating to a road surface. The surface coating agent comprises a principal ingredient consisting mostly of cement silicon dioxide, generally in the form of silica sand, iron oxide, zinc oxide, and glycine and a composite polymer emulsion composed mainly of carboxy-modified styrene-butadiene polymer, wherein the ratio of principal ingredient to the composite polymer is 2.0 to 6.0:1.

U.S. Pat. No. 6,624,232 sets forth polymer modified cement sealer that is laid thinly atop a pavement surface and provides UV and chemical protection to the underlying surface. Owing to its thin-ness, however, it cannot contribute to a significant service life extension of the pavement. Rather, the mixtures coats and seals whatever is beneath the overlay.

In addition, owing to the high cost of fossil fuels, a number of pavement maintenance products have become not only unsafe with respect to the environment, but have also become very expensive for many end users. Especially with respect to the usable life expectancy of these antiquated petroleum based materials, many end users, predominantly Federal, State and Aviation agencies, have been forced to investigate other products that would not only meet their budgetary constraints but also meet many other requirements centered around environmental issues, Solar Heat Reflectivity, comparable durability and rapid re-access to the assets with which the materials are placed. With regards to asphalt pavement; water, UV, hydrocarbons and extended spans between repaving or re-sealing has caused severe oxidation and raveling to many roads, bridges, aviation pavement/operating surfaces, parking lots and vehicular service areas to a point to where expensive reconstruction is the only option. In asphaltic compositions, once the sun begins to evaporate the fine oils that hold the binder together, the small aggregate and sand begin to loosen and gravitate to the road shoulder or curb. At that point, increasingly, all that is exposed is the ¼ to ½ inch polished rock, and even larger aggregate, that decreases the coefficient of friction of the wearing surface. This condition combined with wet weather and oils that naturally leak from passing vehicles can cause an extremely dangerous condition for motoring.

Coal Tar, a by-product of the coal industry, is a very well known and is an effective topical deterrent to asphalt oxidation, exposure to UV and water, as well as to fuel and chemicals. However, the negative aspects of its use have begun to outweigh its advantages. The product is considered to be somewhat to very hazardous to human and animal exposure and animate and inanimate objects. Coal Tar sealers have a significant “tracking” effect that destroys interior flooring to buildings and businesses not to mention passing vehicles. Coal Tar also possesses a very strong odor that remains with the surface for weeks at a time. With regard to human exposure, applicators are exposed to caustic fumes that cause chemical skin burns and has also been believed to cause cancer in certain studies. Coal Tar has been banned from usage in a number of states due to PAH's, a chemical by-product of coal tar that is extremely harmful to humans, animals and the surrounding environment in general. Its continued use in a number of states is based solely on the low cost of the material and its placement.

Another asphalt-based product that has seen a wide range of usefulness is a paving concept called Chip Seal or Chip Sealing. This pavement concept is widely used on county roads due to the low cost and low level of commercial traffic. The chip seal method is constructed of a heavy hot liquid asphalt tack material that is sprayed and sometimes spread with a slurry placement machine. The heavy hot asphalt tack material is then covered with limestone (or other available aggregate) ranging in sizes from aggregate that passes a Sieve Size No. 88 (⅛″) to Sieve Size No. 57 (1.5″), and/or a blend of both inclusive of various sizes inbetween, from a tandem dump truck and spread with a tractor or motor grader. The composition is then rolled with a 14 ton vibratory roller and allowed to cool and harden. Once hard and set, the road is then broomed several times with a commercial street sweeper to remove any loose aggregate. The main deficiency with this pavement maintenance technique is that within a very short time the aggregate begins to loosen and dislodge from the asphalt tack material. As vehicles ride over the surface more stones dislodge and are thrown up into oncoming or following vehicular traffic. This causes an exponential number of cracked and broken windshields and in many cases accidents caused by a build up or concentration of loose aggregate in the road center or edges. As most county roads are only 18 feet to 20 feet wide, there is very little margin for error once this condition develops. However, due to the growing concerns and hazardous events surrounding this concept, most counties have been forced to overlay this type of surface with a 1.5″ asphalt overlay to rectify the liability chip seal roads create.

Concrete on the other hand, has predominantly been a very expensive alternative to asphaltic pavement construction. When crude oil prices were around $20.00 to $30.00 a barrel, asphalt remained the sub-base and surface of choice for public and private roads, parking lots and other transportation wearing surfaces. Presently, however, concrete for the first time in its history has become less expensive than asphalt for the construction of many transportation related surfaces its durability, strength and resistance to UV, water, fuel and chemical spillage is vastly superior to asphalt. However, full-depth concrete also suffers from a number of issues related to structural conditions, extreme chemical is exposure and ride-ability. First of all, concrete is not as smooth a riding surface as asphalt. The construction process is very time consuming causing driver anxiety. Concrete tends to heave in a true plane in expansive soil regions causing vertical separations at each expansion joint. (Asphalt, on the other hand, tends to roll with the heaving soil and crack when its tensile strength is breached.) This is a very dangerous traffic condition for both surfaces which requires planing of the uneven joint to smooth the transition from one panel to the next or the expensive process of panel replacement. Over an extended period of time the top ¼″ “cream” of the concrete wearing surface begins to erode due to traffic, water and basic deterioration. At this point the aggregate becomes exposed which in turn substantially lowers the coefficient of friction for not only concrete roads but bridge decks. The transition from one type of pavement surface to a worn bridge deck surface can be extremely dangerous in wet weather in severe cold weather conditions, depending on the aggregate used in the mix design, the aggregate can freeze in the top 1″ of the concrete profile and cause the aggregate to burst due to the microscopic water polyps inside the concrete aggregate. This condition is referred to as “pop-outs” that can range from ½″ to 2″ in diameter which in turn can and will begin an erosion and concurrent spelling process. As for concrete bridge decks, there has historically been only one alternative for repairing many of the problems that plague old bridge decks reconstruction. This reconstruction process is not only time consuming but also very expensive to State DOT (Dept. of Transportation), budgets. Many of the problems that are systemic with older concrete bridge decks are loss of friction due to exposure of the polished rock aggregate, concrete spalling and substantial aggregate pop-outs. These conditions are responsible for a large number of vehicular accidents in many states that suffer DOT budgetary problems because funds are not available for total reconstruction. Also, older bridge decks, especially those with wood/timber pilings, (characteristic of county roads), cannot withstand the additional weight load of full depth concrete overlays to repair and improve the ride-ability of these older bridge decks.

In an effort to resolve the weaknesses of these pavement materials and structural deficiencies, there have been a number of products that have been introduced to the market to try and minimize, slow down and ultimately stop the conditions and problems that these pavement commodities create with limited to moderate success. With this background synopsis it can be observed that there is a need for a highly evolved polymer modified cement micro overlay formulation, installation and repair method which overcomes the weaknesses of asphalt degradation, chip seal deterioration, coal tar sealer hazards and concrete road and bridge deck spelling, pop-out, cracking, and joint repair. These evolutionary developments in addition to a rapid turn-around with minimal interruption to vehicular traffic are the essence of this invention.

SUMMARY OF THE INVENTION

The present invention advantageously fills the aforementioned deficiencies by providing a universal transportation pavement life extension product and method.

The present invention fills the proven need for a cost-effective, long-lasting, fuel/chemical-resistant, aesthetically pleasing, environmentally-safe and structurally-sound pavement coating system that can be applied to asphalt, concrete, chip-seal and old pavement sealers with state-of-the-art installation equipment and mixing techniques combined with new and improved preparation and pavement repair techniques. The following objects and characteristics explain in further detail the specific needs that are filled based on extensive research and development with the assistance of the US Army Corp. of Engineers, the FAA, and numerous State Dept. of Transportation Authorities. They are as follows.

It is an object of the invention to provide an improved pavement overlay composite material which fills oxidation and raveling voids in asphalt caused by environmental exposure and exposure to aliphatic hydrocarbons.

It is an object and characteristic of the invention to provide an enhanced coefficient of friction to oxidized asphalt roads, parking lots, concrete roads, concrete parking lots, aircraft operating surfaces and concrete bridge decks.

It is an object of this invention to provide a cost effective, durable and long lasting overlay product for deteriorating Chip Seal road surfaces. By encapsulating the oxidized chip seal surface with a polymer modified cement composite overlay material in accordance with the present invention, all stones are locked in place and a new, high strength, high friction structural composite road surface is created.

It is an object of the invention to provide a refined and efficient, high capacity mixing and application process for a smoother surface texture and shorter down time of the pavement work area.

It is an object and characteristic of the invention to provide a light colored finish which provides a cooler surface temperature than that of hot mix asphalt. By providing a lighter color of the finished product, the sub base asphalt material remains cooler and has a tendency to “pump” less.

It is another objective of this invention to provide detailed base preparation and repair techniques and materials applicable to the different pavement types and their respective common problems caused by the environment, vehicular traffic, unstable soil conditions and age.

It is an object and characteristic of this invention to provide a long lasting, highly durable, non-skid surface treatment to specifically older concrete bridge deck surfaces in order to minimize construction costs problems that include but are not limited to spalling, pop-outs and structural cracking and heaving.

This invention also includes an advanced pavement repair method which combines two primary materials, sequentially installed, to provide a durable repair method to pavement cracking, raveled paving seams, expansion joints, cold joints between asphalt and concrete pavements and heavily oxidized and raveled asphalt/concrete pavement. This particular repair method has been proven in the field and provides the following benefits and characteristics:

- A “bridging” of the asphalt/concrete crack, joint or paving seam
- A dissipation of the energy created by the re-occurrence of pavement cracking
- A smooth finished texture of the overall repair method
- A preventative measure in allowing the re-occurrence and reflectivity of pavement cracking and sub-strait movement.

As disclosed herein, the present invention includes three (3) variables.

1) The Overlay Material: the material is a blend of a special high solids acrylic/latex emulsion, a sieved cement/sand blend, water and a sized non-skid high hardness aggregate. When mixed together, this blend of raw components creates a “slurry” type mixture that when applied to asphalt, concrete and other pavement types and cured, possesses improved adhesive characteristics to the underlying overlaid surface, chemical and fuel resistance, resistance to UV degradation, water, salts and deicing fluids and enhances the coefficient of friction lost from past vehicular traffic and weather driven oxidation.

2) The Preparation and Repair Processes Pre-Overlay: There are primarily four (4) different types of transportation vehicular traffic surfaces to which this product and method can be applied: a) asphalt, b) concrete, c) chip seal and d) coal tar sealer overlaid pavements. For each of these pavement types there are specific and detailed repair and preparation techniques which can be used to, for the most part, prepare each surface to better accept the polymer modified cement composition of the present invention.

3) The Equipment: The equipment components are as follows: a) The high capacity (“HC”) mixer: the HC mixer has been designed to take all the raw materials and mix in large quantities and blend the raw material to where no lumps, cement knots or dry pockets prevail from the blending of each ingredient. The mixer ranges in size from 1,000 gallons to 1,500 gallons depending on the size and daily production schedule of a project. It is a combination of a steel tank, gas powered hydraulic system and proprietary interior blade design. b) The Extrusion/Placer machine: The extrusion/placer machine is self-propelled and designed to take between 300 and 350 gallons of the mixed polymer modified cement composition from the HC mixer and place the material on the project substrate with a specially designed extrusion blade that applies a layer between the thickness of ⅛″ to ½″ depending on the oxidation level of the pavement surface. The extrusion/placer machine can place up to 125,000 square feet per day. The extrusion/placer machine has a similar interior mixing blade design as the HC mixer in order to keep the polymer modified cement composition properly blended during placement.

The optional features are that of placement quantity, color of the polymer modified cement composition, and the addition of additional high hardness aggregate and topically applied aggregate for additional skid resistance. The different size extrusion blades that are offered are a 6 foot, 8 foot, 10 foot and 12 foot wide design. The colors of the polymer modified cement composition that are offered are standard concrete gray and black. Specially sized mixing tanks can be built depending on the contractors specific requirements. The only difference is that of quantity (size). All other components of the HC mixer remain the same.

The present invention provides substantial advanced improvements over other similar coating/product designs, compositions, mixing and application procedures. This invention also includes comprehensive cleaning, sterilization and specific repair techniques applicable to the different pavement substrates in order to provide the following:

- Advance preparation and repair procedures for different pavement types
- Enhanced coefficient of friction for all pavement types
- Improved adhesion to asphalt, coal tar, asphalt rejuvenators and concrete
- Comprehensive base preparation techniques prior to installation
- An advanced concrete bridge deck repair and non-skid surfacing method
- A new alternative to repairing “Chip Seal” road surfaces by structural encapsulation
- High capacity mixing and application
- Rapid in service turn-around for public and private facilities

This invention offers something that no other known process provides: that is, the overall combination of multiple variables to provide the end user with a proven and complete system to repair and maintain transportation vehicular pavement with a state-of-the-art material, state-of-the-art equipment and proven preparation and repair methods

Finally, it is an object of the present invention to provide a universal transportation pavement life extension method that does not suffer from any of the problems or deficiencies associated with prior solutions.

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, which are intended to be read in conjunction with both this summary, the detailed description and any preferred and/or particular embodiments specifically discussed or otherwise disclosed. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of illustration only and so that this disclosure will be thorough, complete and will fully convey the full scope of the invention to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of the High Capacity Bulk Mixing Machine.

FIG. 2 is a front view of the mixing machine shown in FIG. 1

FIG. 3 is a rear view of the mixing machine shown in FIG. 1

FIG. 4 is a partial view inside of the mixing tank of the mixing machine of FIG. 1 showing the internal mixing blade design.

FIG. 5 is a partial end view section showing the mixing blade of FIG. 4.

FIG. 6 is a schematic side view of a self propelled, extrusion machine used in the present method.

FIG. 7 is a schematic plan view of the 12′ extrusion blade mounted behind the machine shown in FIG. 6.

FIGS. 8(
a) and 8(b) are schematic representations of a rubber squeegee attached to the angle iron elements, of the extrusion blade assembly in FIG. 7, on the mid, end plate, and side plate angle iron elements thereof.

FIG. 9 is a perspective view showing the high capacity mixing machine of FIG. 1 charging (filling) the self propelled mixing and extrusion machine of FIG. 6 in accordance with the present method.

FIG. 10 is a partial sectional view of the polymer modified cement composition of the present invention placed over an asphalt or concrete substrate.

FIG. 11 is a cross section of a repaired full depth pavement crack using the process described herein.

FIG. 12 is a cut-away perspective view of a repaired full depth pavement crack using the process described herein.

FIG. 13 shows the “leveling step” in the crack repair process described herein.

FIG. 14 shows the crack process ready for the “encapsulation” step following the rolling of the fabric.

FIG. 15 shows the encapsulation step of the process described herein.

FIG. 16 is a cut-away view showing the leveling layer beneath the rolled fabric with a partially finished encapsulation layer.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed and specific explanation and description of the inventions herein. This description includes a technical characterization of all components of the pavement overlay material mixture, the equipment and specific, proven repair and preparation techniques/procedures that, when properly combined, create the long term durable pavement overlay of the invention. The method and product herein directly addresses the pavement life extension of asphalt, concrete and asphaltic based “chip seal” roads, bridges, parking lots and aircraft operating surfaces.

As an integral part of this invention, the surface preparation and repair of each type of specified pavement type is equal in importance and relevance to the later applied overlay material and method of application.

Asphalt Pavement Preparation and Repair Method Prior to Overlay (Minor to Moderate Cracking Evident):

For asphalt surfaces, the pavement should preferably be degreased and/or pressure washed with an effective degreasing agent, of which many are available and are not proprietary. The degreaser is applied to the asphalt pavement surface, scrubbed with an appropriate heavy duty broom, brush or street sweeper, then steam cleaned with a 3,500 PSI, 200° F. steam cleaner. If old traffic striping is present, the markings are removed with the same steam cleaner that is used with the degreasing of oil spots and fuel spills. If wheel rutting or cracks are present, a polymer modified cement material can be used to pre-fill these areas to within 1.5″ of the original elevation. The repair material mixture of the polymer modified cement material is mixed with an additional additive of angular aggregate chips (#12 sized granite is preferred, but a sieve size larger or smaller would also be acceptable). The steps of the repair process for rutting and sink holes, pre-final overlay, are as follows:

(i) The surface must be relatively clean and dry

(ii) A batch mixture applicable to the area to be repaired can be blended in a 9 cubic foot mortar mixer with the following preferred recipe: a) 1.5 gallons of Component A—latex emulsion, b) 75 lbs of Component B—dry cement powder blend, c) 15 lbs of Component C (1) #12 angular granite aggregate, ½ to ¾ of a gallon of water. All components are blended into a consistency that is void of all dry powder pockets and solids.

(iii) The composite blend is then placed in the hole or wheel rut and screeded with a magnesium strike-off or straight edge.

(iv) if the area that is full depth repaired is longer than 3 feet and wider than 1.5 feet, the placed polymer modified cement composition patch should be scored with a hand trowel or knife, full depth every 12 inches to prevent cracking and enhance curing.

(v) Once fully cured, (2 to 3 hours), a layer of a 12.5 mm×12.5 mm (½″×½″), open mesh, woven fiberglass, geotextile paving fabric is cut to the desired width and is applied with the adhesive side down onto the patch and rolled down (vehicle tire pressure is sufficient) to ensure adequate adhesion to the surface leveled with the polymer modified cement composition.

(vi) The final step of this pre-repair process is to apply a smooth overlay of the patch with primary mixture of the polymer modified cement overlay material as specified above with a squeegee or modified rubber pull blade applicable to the width of the patch in order to encapsulate the completed repaired area with the geotextile fabric.

Major Full Depth Pavement Crack Repair Method

A full depth pavement crack is a crack that extends through the wearing course(s) to the pavement binder and potentially to the underlying base material (packed aggregate).

The following steps will describe the major crack repair process and how the process works. The steps described will be correlated below as to drawing FIGS. 11-16.

- 1. The full length and breadth of the crack (tests, field research and actual commercial applications have been used on cracks as wide as 6″ and depths of about 8″), should be thoroughly cleaned and sterilized to the extent possible in the field conditions. This is accomplished by removing any debris with an appropriate digging tool, then pressure washing the crack area to remove any dirt or organic contamination. After pressure washing, the crack is then blown out with a high pressure air blower. Once dry, if any vegetation remains, the crack is then sterilized with a heat lance burning device or steam jet, blown clean, and allowed to dry again.
- 2. Once the crack(s), have been properly prepared, two-component bonding epoxy (100% solids preferred) is mixed and placed into the crack up to about ½ the depth of the crack wall. In order to guarantee adhesion between the bonding epoxy and the polymer modified cement leveling course, #4 or #6 quartz (or other high hardness, i.e, granite) aggregate is spread into the wet, uncured epoxy to provide an aggressive profile.
- 3. After approximately three (3) hours, the epoxy primary filler is then ready for the polymer modified cement leveling course (FIG. 13). The leveling course material is mixed to the mix design noted herein for Alligatored Asphaltic repair except for the additional mixing of 30% more, (e.g., 150-400 lbs of aggregate to 55 gallons resin), of the #4 quartz (or other high hardness aggregate, including up to #16, or ⅜″ size) aggregate in order to provide more structural integrity inside the crack depth. This material mix is then applied with an eighteen (18) inch wide pull blade to bridge the crack and extend out beyond each side of the crack area (approx. 4-8 inches) to facilitate the next step in the process. This step requires twelve (12) hours to fully cure prior to Step 4.
- 4. Step 4 utilizes a self-adhesive(preferred) or non self adhesive, fiberglass, open mesh paving fabric within an aperture size of about 6.5 mm×6.5 mm up to and in between about 25 mm×25 mm, (about 11.0 oz per SY and an approximate 100 kN/m Tensile Strength across width and across length). Prior to the application of the fabric, the semi-repaired crack area is scraped of any high spots or material drips and blown off to remove any debris. The preferred fabric typically comes in five (5) foot wide rolls, but is cut longitudinally for the special needs of the cracks that are being repaired. In most cases the width of the rolls is cut to fifteen (15) inches wide. The fabric is then rolled out to the required length, cut and turned over to place the adhesive side (if present) down onto the cured polymer modified cement leveling overlay. At that point the slack is pulled out and the human applicator walks down the placement area to remove any slack or “crimps” in the fabric profile. Once the fabric placement is straight and in position, the fabric is rolled with a (% ton preferred) truck tire at least two (2) times to insure adequate adhesion between the fabric and underlying polymer modified cement in preparation for the next Step of the process. The resultant in-place rolled fabric is shown in FIG. 14.
- 5. The next to last step (shown in FIG. 15) of the process is to “encapsulate” the entire matrix of the first polymer modified cement layer and the rolled paving fabric into a fully integrated structural system that will dissipate and spread the energy that would otherwise re-crack the pavement when it is returned to use. This re-cracking energy can come from many variables, (temperature variations, minor sub grade movement and vehicular compressions). This encapsulation step preferably embodies the application of a further (about 0.25 to 0.75 inch thick) layer of polymer modified cement preparation over the rolled paving fabric to fully saturate and “encapsulate” the fabric profile. Once allowed to cure for approximately twelve (12) hours the surface will then be ready for the final wearing surface overlay system. The final layer could be another layer of polymer modified cement material or other traffic suitable overlay.
- 6. An optional additional step, for highly worn and damaged concrete bridge decks, is to apply a further encapsulation layer so as to extend the life of the repair system in the wheel lanes only. This is accomplished in one of two ways.
  - (i) An additional layer of the open mesh fiberglass paving fabric can be placed over each wheel lane directly onto the concrete crack repair after any and all repair work has been placed and allowed to cure. Once placed and seated, the mesh is then encapsulated with the polymer modified cement mixture onto and in the wheel lane or “rut” giving additional structural integrity to the weakest area of the concrete. This is accomplished prior to the final wearing course layer of the polymer modified cement being applied over all of the repaired areas.
  - (ii) Also, a second layer in the width of the wheel lanes only, (from 2 ft to 4 ft), can be applied on top of the entire system once it has cured.

Method of Repairing and Preparing Severely Alligatored and Deteriorated Asphalt Prior to

Overlay

The asphalt specific pavement repair method described in this subsection addresses the repair and preventive maintenance of severely deteriorated and cracked asphalt pavement prior to an overlay using the primary system herein. However, due to the ever changing problems created by sub-standard, sub-base soil conditions; this method and material is not recommended for asphalt pavement that possesses and retains structural “pumping” conditions caused by expansive soils and clays found in a large part throughout the southeastern United States. As such, this asphalt pre-repair method and material addresses severe “alligator” cracking only on a relatively stable pavement base where water intrusion, hydrocarbons, UV degradation and basic lack of maintenance has caused the asphalt pavement to create semi-stable “islands” with a minimum size of 3″ to 5″ in diameter contained within medium to large areas of heavy vehicular traffic. These “islands” are separated from each other by cracks around the entire perimeter of the “island” ranging in width from ¼″ to ⅓″ and have been found to be as deep as 1″ up to 4″ deep. The following method and material have been developed and tested in the field and are currently being installed on commercial heavy industrial vehicular pavement areas prior to the application of the primary polymer composite micro overlay system.

Alligatored Asphalt Preparation Method

When dealing with severe alligator cracking on asphalt, one must insure that the pavement area is not “pumping”, (movement up and down caused by expansive soil clays that expand when wet and contract when dehydrated). This pavement condition is best corrected through removal of the asphalt and sub base down to the certified depth for the region and replaced with fill material engineered and approved by the local geotechnical engineering authority. However, if the base is semi-stable, (no pumping), the pavement preparation consists of heavy cleaning through the use of a 3,500 PSI pressure washing machine to remove any and all granular, oily and vegetative contamination in and around the “island profile” of the deteriorated asphalt pavement area. In order for the described system to perform, all cracks surrounding the asphalt “islands” should be clean and open to insure a full depth penetration of the polymer composite mixture.

Mixing of the polymer composite first layer, (initial repair leveling course).

This mix design for the alligatored initial overlay is different than the primary mix design herein in that the latex emulsion content may be much higher than that of the standard polymer composite micro overlay systems eventually applied as the top wearing course overlay. This leveling course mix design, produced in a standard 9 cubic foot mortar mixer, (for ratio descriptive reasons only) has the following formulation in a preferred embodiment:

- Twenty (20) gallons, (176 LBS), of a blended mixture of DOW 413 Latex Emulsion, having a polymer solids content of about 46-48%.
- 480 LBS of Quickrete Cement dry blend, (1 part Type I Portland mortar to 3 parts 60 to 120 washed mason sand).
- NO WATER
- Composite mixture is thoroughly blended until composition texture is to a “loose-creamy” consistency.

Application of First Layer leveling course to Alligatored Asphalt:

This blended material is then poured onto the alligatored asphalt substrate and spread evenly with an applicable squeegee, (36″ wide recommended), to adequately allow the material to fill all the crevices and cracks surrounding the “alligator cracking” surrounding the deteriorated asphalt islands. The consistency of this blend is such that it is “self-leveling” and fills all areas of cracking normally after the first pass of the squeegee. If another pass is required it is done while the existing layer is still wet and uncured. To enhance the adhesion of the second and final layer of the repair process, #4 quartz sand aggregate is manually spread while the leveling course is wet at a rate of no less that two (2) pounds per square yard.

Before the second layer can be applied, the primary leveling layer must cure from 3 to 5 hours. Once the material is cured enough to walk on, a second wearing course layer of the primary polymer modified cement overlay is applied with the applicable application equipment and standard mix design as set forth within the balance of this specification.

In an example of the above application: One (1) week of heavy vehicular traffic, exposure to hydrocarbons and rain; Temperatures for the week ranges from mid 80's to mid 40' a each day and night (therefore thermal expansion was expected); No visible signs of any hairline cracking, efflorescence or decomposition appeared in any form.

Chip Seal Road Pavement Preparation and Repair Method:

For Chip Seal road surfaces, extraordinary care must be taken to remove any and all loose stones from the road bed surface. This can be accomplished by facilitating a heavy duty commercial street brooming machine making consecutive passes down each side of the road until all loose aggregate is removed (2 to 4 consecutive passes). Upon completion of the brooming, high pressure, compressed air is used to remove any dust or organic debris prior to spot repair using the polymer modified cement composition with the #12 granite aggregate. Any and all bare spots, holes and sparsely covered sections of the road bed are then repaired with the polymer modified cement composite material mixed with the #12 granite aggregate, as described above, and placed with a squeegee, magnesium straight edge or rubber squeegee pull blade in order to fill the voids prior to an overall resurfacing with the polymer modified cement composition overlay system as detailed herein.

Concrete Road and Bridge Deck Pavement Preparation and Repair:

Since concrete is a porous compound, care should be taken to remove all contamination from the micro subsurface of the top of the concrete pavement. This can be accomplished, for example, by mixing a combination of 1 part phosphoric acid (75% concentration) with 5 parts water. The acid wash is then spread evenly over the entire concrete surface and immediately pressure washed with the 4,000 psi, 200° F. steam cleaner. This combination of chemicals, heat and water pressure has proven to be a more than adequate method for removing organic contamination deep within the pores of the concrete surface, concrete spalling, loose unbroken aggregate pop-outs and the acid/water residue. Note: Phosphoric acid is preferred due to its ability to break down and become inert immediately after its efflorescence and exposure to the concrete surface. The residue can then be washed off onto the road shoulder or over the bridge deck. The preferred concrete repair methods are herein described as follows:

I. Spalling

(i) After cleaning and removal of any spalling discovered during the hydro blasting process, the pavement surface or bridge deck surface is then “chained” using a device developed to expose hollow areas within the top ½ to ¾ inch deep top layer of the concrete surface. The hollow areas are exposed by an audible hollow sound to determine the size and depth of the uncovered spalled areas to be excavated and repaired. The lower the pitch of the chain dragging over the concrete surface is positive evidence of concrete spalling from ¼″ to ¾″.

(ii) Once these areas are marked and removed (with light chipping hammers), the areas are cleaned with high pressure compressed air and filled with the polymer modified cement composition mixed with the #12 angular granite aggregate described above as in the Asphalt Pavement Preparation and Repair section portion of this specification.

(iii) Once the spalled areas are filled and have cured (3 to 5 hours), a second over layer of the polymer modified cement composition as referenced herein is placed over the primary patch to smooth out and level any rough or uneven profile of the surface texture.

II. Cracking

(iv) If any cracks exist, they are cleaned out with the mentioned steam cleaning machine and then blown dry with high pressure compressed air. Depending on the width and depth of the cracks, several different products are applicable. However one specific concrete crack repair material has proven to exhibit desired characteristics in regards to absorbing active crack energy and offering the polymer modified cement composition substantial bonding characteristics. This material, ULTRABOND 2100, manufactured by Sonneborn Chemicals is a two-component, self leveling, concrete epoxy that is applied by bulk caulk guns.

(v) The crack(s) to receive the Ultrabond 2100 treatment are filled to within 1 to 1.5 inches from the top elevation of the crack with an appropriately sized foam backer-rod.

(vi) The Ultrabond 2100 two-component, self-leveling epoxy is then placed into the crack(s) with high capacity, bulk caulk guns and allowed to cure for 30 to 45 minutes.

(vii) At the end of the curing time of the Ultrabond 2100 crack epoxy (30 to 45 minutes), a leveling layer of the polymer modified cement composition is then placed over the crack filled with the Ultrabond 2100 and allowed to cure for approximately 1 to 2 hours depending on the thickness and the porosity of the concrete bridge deck surface. The concrete surface is then ready for the polymer modified cement overlay material and method.

Wearing Course Polymer Composite Overlay Application:

The applied material composition and equipment detailed herein allows a ⅛″ to ½″ thick layer to be extruded onto semi-stable pavement surfaces (prepared as noted above where necessary) such as asphalt, chip seal and deteriorated concrete, that when cured forms a durable membrane which adheres to the pavement surface, fills the voids caused by raveling and oxidation, and provides a non-skid wearing course to the repaired pavement surface. The polymer composite overlay material is preferably applied all in one single pass with the self propelled secondary mixing and extrusion machine as disclosed herein.

A preferred formulation of the top wearing course polymer composite overlay material includes the following:

Component A—An approximately 50/50 (45/55 to 55/45) by volume blended combination of: UCAR® Latex 413 and UCAR® Latex 651; both of which are Manufactured by the Dow Chemical Company, Midland, Mich.

UCAR Latex 413 is an acrylic emulsion polymer developed for use in the polymer modification of Portland cement and other hydraulic cement compositions. It has a polymer solids content of about 46-48% by weight, a pH of 9.0-9.5, viscosity (LVT#3, 60 rpm, cps) of 50, a weight per gallon of 8.8 lbs at 20 degrees Celsius.

UCAR 651 is an acrylic copolymer resin emulsion of high molecular weight developed for the coatings industry. Its use is intended for interior and exterior paints. It has a polymer solids content of about 65% by weight, a pH of 9.0, viscosity (LVT #3, 50 rpm) at 20 degrees Celsius of 400, a weight per gallon of latex (9.0 lbs.) of polymer (9.4 lbs.). It can be used in exterior surface coatings (i.e., a preferred binder in tennis court coatings, traffic paint, and barrier coatings).

The following is an approximate analysis of the characteristics of the respective DOW UCAR Latex 413 and 651 products once blended to form Component A:

Component
CAS-No.
Concentration

Polymer (BAIMMA)
25852-37-3
52-59% by weight

Residual Monamers
Not required

Aqua Ammonia
1336-21-6
≦0.3%

Hydroxyethyl Cellulose
QP-4400H
3%

Glycol Surfactant

25%

Water
7732-18-5
19.6-21.5%

The Hydroxyethyl Cellulose QP retards efflorescence in the set material, the Glycol Surfactant enables more pliability when the emulsion is mixed with a cementitious blend of Type I Portland Cement and aggregate, (sand blend). The actual percentage of solids in the latex itself is preferably in the range of about 54 to 58% by weight, or providing a polymer solids content in the range of between 5% to 12% by weight in the mixture. Because of this, adhesion is the highest with respect to a variety of substrates and pliability is equally substantial. Once in place, reflective cracking, except for structural movement caused by expansive soil conditions, is minimal in a treated pavement. In placed examples, cracking has not returned within 60 days of placement and in-service use, despite highly expansive soil conditions with freeze thaw.

The foregoing latex emulsions are currently delivered separately in 55 gallon plastic drums, non pigmented and blended as specified by the manufacturer. The two (2) emulsions are then blended together to form the approximate 50/50 mixture by volume according to the present invention.

Component B Cement Dry Blend, (1 part Type I Portland, 3 parts 60 to 120 mesh washed mason sand). Manufacturer: SpecMix STM, Harahan, La. The Cement dry blend, (aka, sand topping mix), is a standard blend powder formulated that is pre-blended at the manufacturing plant and delivered in 2,800 LB tote sacks. The finer mesh sieve sizes from 90 to 120 gives the material composition the ability to be feathered to a fine layer in circumstances surrounding placement along curbs, retaining walls and around drains and man-holes.

Component C Granusil #4 Quartz (or other high hardness aggregate (i.e., No. 10, granite); Manufacturer: UNIMIN Corporation, Knoxville, Tenn. The Granusil #4 Quartz or other high hardness aggregate (i.e, granite chips) is generally delivered in 100 LB bags, 30 bags per pallet.

Each “kit” of the above mixture, (one mix of Component A, B and C), includes 100-400 LBS of the Component C non-skid aggregate. Durable high hardness aggregate resists abrasion in high traffic/excessive wear applications and provides the stability formulators sought in high solids emulsions like the blended UCAR Latex described above, elastomerics, cemented and modified cementitious systems. Granusil or other high hardness aggregate is the preferred structural component in systems ranging from polymerized pavement overlays to artificial sports turf. The aggregate is maintained in suspension in the blended mixture by the high viscosity of the blend. In addition, the aggregate supplies added strength and yet workability of the mixture is maintained during the placement phase (1-2 hours). During particularly low humidity conditions and/or high heat, discretionary addition of water is advisable to account for rapid evaporation.

On project locations, the latex provided in 55 gallon plastic drums is pumped into the 1,000 to 1,500 gallon, high capacity batch mixing machine 10 as shown in FIGS. 1-3 located on a 24′ flatbed HD truck 91 with mobile crane 92 (see FIG. 9) and/or an extended reach forklift. A single batch kit as previously explained consists of 1-55 gallon drum of Component A—latex emulsion, 1-2,800 LB tote bag of Component B—cement dry blend and 1 to 4 100 LB bag(s) of Component C #4 Quartz non-skid aggregate. A normal job mix is 4 complete kits mixed simultaneously in the 1,500 gallon high capacity mixing machine 10 for approximately 20,000 square feet per full tanker load). Therefore, 4-55 gallon drums, (220 gallons), are pumped into the already agitating high capacity mixer 10. Once the latex emulsion is loaded, 25 gallons of potable water per kit (100 gallons per full job mix), is then pumped into the agitating mixer machine 10. The truck mounted crane then lifts each 2,800 LB tote bag of Component B over the screened man-hole opening 14 at the top of the mixer and gravity feeds the dry blend at a set rate which is determined by a relief valve at the bottom of each tote bag of cement dry blend. Once all four bags have been placed into the agitating mixer, the four-sixteen 100 LB bags of Component C—the high hardness #4 non-skid aggregate are placed in the mix by a technician at the top of the mixer machine. The composite blend is allowed to mix for 5 to 15 minutes prior to charging the self-propelled secondary mixer extrusion machine 50 for material placement.

While the above described formulation is preferred for the top wearing course polymer composite overlay material, the quantities of Component B and water can be varied for each 55 gallons of latex. Specifically, the ratio of Portland cement/sand can vary from about 1/2.5 to about 1/3.5. The quantity of Component B in each kit can be as low as 2650 pounds to as much as 3000 pounds per kit. And water can be present in amounts between about 15 gallons and about 35 gallons per kit.

Once the overlay composition is placed, if further enhancement of skid resistance is desired, an air powered distribution gun (typically used in the textured drywall field) is used at 85 psi to evenly distribute 1-2.5 lbs of non-skid aggregate per square yard of placed overlay material. The non-skid aggregate can be any high hardness aggregate that can embed into the overlay surface and be retained by the modified cement mixture. The #4 quartz aggregate and #10 granite have been found to work well in this application.

Testing Results: The primary overlay (top wearing course) material produced according to the “kit” composition herein has exhibited improved results in standard ASTM testing. (C109-Compressive Strength, C190-Tensile Strength, C157-Length Change, C1583-Bond Strength, D4090-Taber Abrasion Results 500 g load). Mix at 58% latex solids, and 2×100 lb bags of #4 Quartz aggregate.

Compressive

Strength (psi)
Tensile
Length Change %

Air Cured
psi
Strength psi
Cure
Air
Moist

3 days
160
50
14 Days
−0.081
0.023

7 days
380
110
18 Days
−0.096
0.024

28 days
1220-1390
380
21 Days
−0.110
0.024

28 Days
−0.116
0.024

Bond Strength

Peak Pull Off

Load (lbs)
Bond (psi)
Mode

1^stSample:
1,164
196
Asphalt/Repair Product

2^ndSample:
1,008
170
Asphalt/Repair Product

3^rdSample
688
116
Asphalt

Avg.
953
161

Taber Abrasion Results with 500 g Load

Initial Weight
End Weight
Cycles
% loss

1^st
504.60
493.02
1000
2.3

2^nd
546.22
535.28
1000
2.0

3^rd
514.18
503.47
1000
2.1

Avg.
2.1

Skid performance numbers for the mix of the present invention using the ASTM 274 standard: 60 km/hr. produced a friction number of about 54.

FIG. 1 is a representation of the High Capacity Bulk Mixing Machine 10. The machine/tank 11 has a capacity of 1,000 to 1,500 gallons of mixed polymer modified cement composite material. The tank mixing system is powered by a Honda 18.5 HP gasoline engine 12 which operates a hydraulic hydrostatic drive system 15 controlled by a small joy-stick 18 approximately 38″ up from the bottom “I” beam on the front of the machine. The joy-stick mount is attached to the tank itself which controls the direction and speed of the internal rotation of the mixing blade assembly 30. The tank 11 is further equipped with steps 13 and a hand rail 16 to allow technicians to observe mixing and mixture within the tank 11.

FIG. 2 is a view of the front and rear of the mixing machine 10. The front of the machine holds the power plant 12 and hydraulic drive systems 15.

FIG. 3 presents a view of the rear of the mixing machine 10. The rear of the tank 11 is the location of the 4″ butterfly valve 17 that discharges the polymer modified cement composition material through a quick release, bulk cement hose 19 into the self-propelled extrusion machine 50 for placement.

FIG. 4 is a view of the inside of the mixing tank 11 to display the internal mixing blade design 30. There are 5 full length blades 32 (oriented at alternating 90 degree positions along shaft 34) welded to a 3″ diameter solid steel shaft 34 that sweep the full diameter of the inside of the mixing tank 11 in order to remove any material from the inside skin of the steel tank 11. Each full length blade 32 has 24¼″ steel blade plates 35 that measure 3″ wide by 18″ long and are welded on both ends and sides to the 3″ angle iron full length blades 32. All ¼″ steel plates 35 are set at a 45° angle for a maximum attack against the polymer modified cement blend as the different raw materials are placed into the mixing chamber. FIG. 5 shows an end view of the 90 degree oriented mixing blades 32.

FIG. 6 is a schematic rendering of the self propelled, extrusion machine 50. This machine is designed to accept a 350 gallon load of polymer modified cement composite material into mixing tank 52 through the 4″, 90°, quick release coupling 54 at the top of the machine behind the engine and hydraulic system. This machine is propelled by a Kubota 35 HP diesel engine 55 and hydrostatic drive system 56 which operate all controls. The controls are as follows: a) the hydrostatic drive system 56, b) the lifting actuator cylinder 53 that raises and lowers the toe arms 57 that hold the extrusion blade 70 at a specified elevation from the pavement surface, c) the release valve 58 that allows the polymer modified cement composite material to flow into the initial extrusion chamber, d) the steering 51 and internal rotation of the mixing blades 59 (shown as dotted inside tank 52).

FIG. 7 is the schematic drawing of the 12′ extrusion blade 70. The blades come in 16′, 12′, 10′ and 8′ pre-fabricated single unit designs. The initial chamber 72, (the top section in the diagram), is the section of the extrusion blade that spreads the polymer modified cement composition across the full width of the blade 70 to the end blades 74 on each end. The end blades 74, (at the lower right of the diagram) are designed to preset the adjustable height of the blade system in order to compensate for pavement surfaces that require a thick wearing surface or a surface that requires grooving for hydro-migration. The back chamber 71 of the blade is designed to allow any out-gassing of air that was trapped in deep pockets within the pavement profile that were created by abnormal or heavy oxidation and raveling. Due to the recommended pace of the extrusion machine 50, (0.75 meters per minute), air trapped by the primary chamber 72 is allowed to escape and the second chamber 71 fills the voids caused by the bubbles and then provides the smooth surface texture designed and described within this invention method. The extrusion blade 70 is constructed overall of ¼″ steel angle iron, 1/16^th“plate steel, 60 durometer neoprene rubber (for squeegees 78) and 2 in. wide squeegee brushes 79 for the end blade assemblies 74.

FIG. 8 is a schematic representation of how the rubber squeegee 78 is attached underneath to the angle iron extrusion blade assembly thus creating two spreading chambers 72 and 71 that apply and re-apply the polymer modified cement composite material from the respective chambers of the extrusion blade 70 to the surface beneath.

FIG. 9 displays the high capacity mixing machine 10 charging, (filling), and the self propelled mixing and extrusion machine 50. The method is designed to make systemic and consecutive passes at minimum 12′ widths, overlapping each prior placed pass by not more than about 4″.

FIG. 10 is a partial side sectional illustration 100 of the polymer modified cement composition 102 placed and finished over the asphalt or concrete substrate 104. In section: (i) The ⅛″ to ½″ polymer modified cement composite overlay material 102; (ii) The asphalt or concrete substrate 104; (iii) The compacted, granulated sub-base material 106.

Full Depth Crack Repair Method:

FIG. 11 is a sectional view (and likewise in the FIG. 12 perspective view) of a pavement repaired using the major full depth repair method detailing all levels of the process. To wit:

- a) 200 is the semi-stable substrate, (asphalt, concrete or chip seal pavement)
- b) 202 is the two-component epoxy bonding agent and waterproofing compound installed in the bottom % depth of the structural crack or paving seam.
- c) 203 is the self-leveling layer of the high aggregate content polymer modified cement.
- d) 208 is the 6.5 mm to 25 mm self-adhesive or non-adhesive, fiberglass woven fabric.
- e) 205 is the final “encapsulation” upper layer of the polymer modified cement composition, and 204 is the lower layer thereof, beneath the fabric, both 204 and 205 sandwiching the fabric 208.
- f) 206 is the “optional” third layer of polymer modified cement material over heavily deteriorated concrete bridge decks to extend the life of the repair method under intense vehicular traffic conditions. Note: this top layer can also be grooved in a transverse pattern to enhance hydro-migration.

FIG. 13 shows the “leveling step” in the major crack repair process described herein. Following the initial cleaning and epoxy application, the epoxy 202 is allowed to cure to a semi-hard state. Once the epoxy reaches this “semi-hard” state, #4 or #6, 2095 quartz (or other high hardness) aggregate 207 sprinkled onto the epoxy to offer the further layer of polymer modified cement 203 a structural bond in addition to a chemical bond. Typically the polymer cement material is mixed in a mortar mixer and thereafter poured into a drag or push type screed box 300. This screed box 300 includes side brushes 302 and squeegee edge 304 to level and smooth the applied material 203 as it spreads into and levels the crack with the surrounding surfaces of the repaired roadway 200.

FIG. 14 shows the crack process ready for the “encapsulation” step following the rolling of the fabric 208 by a suitable tired vehicle. The rolling assures good adhesion of the fabric 208 to the leveling layer 203 prior to encapsulation by layer(s) 205/204. Once again, as shown in FIG. 15, drag box 300 is used to apply the layer 204/205 to sandwich the fabric 208 against the leveling layer 203. The polymer cement encapsulation material is mixed and applied as shown through the drag box 300.

FIG. 16 shows the leveling layer 203 beneath the rolled fabric 208 with a partially finished encapsulation layer 204/205. The coin shown for scale purposes in this installation is a U.S. 25 cent piece. FIG. 13 shows a major crack repair now ready (as for layer 205) for an overlay (or multiple overlays) of wearing course to finish the return to service traffic lane.

In summary, the invention is an overall environmentally safe Pavement Life Extension Method™ to repair and protect different compositions of transportation related pavement from the harmful effects of oxidation, raveling, and structural foundation problems caused by water, UV, exposure to aliphatic hydrocarbons, (fuels, hydraulic fluids and other chemicals), subsurface soil conditions and age. The invention is also designed to provide a long lasting, high coefficient of friction to these different pavement compositions with minimal downtime for construction and vehicular interruption and a cost-effective value proposition for municipal, government and private industry budgets.

While the present invention has been described above in terms of specific embodiments, it is to be understood that the invention is not limited to these disclosed embodiments. Many modifications and other embodiments of the invention will come to mind of those skilled in the art to which this invention pertains, and which are intended to be and are covered by both this disclosure and the appended claims It is indeed intended that the scope of the invention should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings.

	Number	Date	Country
Parent	12337889	Dec 2008	US
Child	12542916		US

PAVEMENT LIFE EXTENSION PRODUCT AND METHOD

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