WO2015087225A1

WO2015087225A1 - Modified asphaltic material for repairing paved traffic surfaces, and method for producing same

Info

Publication number: WO2015087225A1
Application number: PCT/IB2014/066650
Authority: WO
Inventors: Arnoldo Emilio DELGADO TOBON; William APERADOR CHAPARRO
Original assignee: Universidad Militar Nueva Granada
Priority date: 2013-12-12
Filing date: 2014-12-05
Publication date: 2015-06-18
Also published as: CO6970123A1

Abstract

The invention relates to a technology for producing an asphaltic mixture consisting of a mixture of an asphaltic solution (6) formed by binders found in various forms in nature or produced by man, post-consumption polymeric material (PET, PEAD, PEBD inter alia), aggregates (stone), and plant fibres, for permanently incorporating into repairs of roads, motorways and other heavy goods vehicle traffic surfaces by means of an injection patching method.

Description

MODIFIED ASPHALT MATERIAL TO REPAIR PAVED TRAFFIC SURFACES AND METHOD OF MANUFACTURE OF THE

SAME

Object of the invention

The present patent application relates to the manufacture and implementation of an asphalt mix based on post-consumer plastics ideal for patching or patching paved surfaces of streets, avenues and highways and in parallel to solve the growing problem of scarcity in methods of recycling and use of waste in an economically, technically and environmentally more favorable way.

Field of the Invention

The present invention has its application within the field of the construction industry and more specifically in the industry dedicated to the construction of public roads, as well as in the companies responsible for maintaining them.

Background of the invention

Asphalts are those dark-colored liquid, semi-solid or solid substances, essentially composed of hydrocarbons soluble in carbon sulfide for the most part and derived from natural deposits or obtained as waste from the treatment of certain crude oils by distillation or extraction, whose qualities binders and physical and chemical properties make them optimal for application in the construction of vehicular roads.

For the production of asphalt mixtures, bituminous binders are used, among which are: natural asphalts, asphalt cements or penetration asphalts, liquid asphalts or reduced asphalts, asphalt emulsions and crude oils.

Asphalt is composed of numerous hydrocarbons mixed in different proportions. When grouped together, the molecules generate a structure characteristic colloidal where the heaviest molecules are grouped together to form micelles (the asphalt in a dispersed phase), while the lighter ones constitute the intermicelar fluid or continuous phase (dispersion medium). By removing the lightest petroleum hydrocarbons by distillation, the heaviest ones cannot be kept in solution and are joined by adsorption to the existing micelles, increasing their volume as the distillation ends.

Asphalt is made up of asphalt and maltreatment. The former are soluble compounds that are precipitated from crude oil by the addition of a number of 40 volumes of n-pentane. They are responsible for the structural characteristics of asphalts, their content varies between 15 and 20%. Maltenes are the soluble fraction in low boiling saturated hydrocarbons. Generally there is a greater proportion of maltensions than asphalte us and this is what gives the asphalt quality.

The production of modified asphalt consists of the addition of polymers to conventional asphalts in order to improve their mechanical characteristics; that is, its resistance to deformations due to weather and traffic factors (vehicle weight); In addition, they increase the adhesion at the interface between the stone material and the asphalt material, while still retaining it in the presence of water. These mixtures increase resistance to deformation, repeated stress stress and, therefore, fatigue, reduce cracking, as well as the susceptibility of asphalt layers to temperature variations.

The modification of the asphalt has been documented in several patents where the advantages and the processes of obtaining them are mentioned. Thus, U.S. Patent No. US5702199 teaches an asphalt paving material that includes from 5 to 20 percent or more of recycled granular plastic, which complements or replaces the aggregate gravel component of the mixture. The material produces a structurally superior paving material with a longer lifetime. The paving material includes any and all kinds of recyclable plastic, including thermosetting plastics and other plastics which has little or no current widespread utility. The material produces pavements of greater strength with less thickness than those of common asphalt, have greater impermeability to water and is useful for all layers under the surface layer. The recyclable plastic component of the material is preferably a mixture of all recyclable classes from 3 to 7 or of materials of this type of classes from which the most valuable recyclable materials have been selectively removed.

Similarly, patent document No. US6362257 teaches a composition for patching the pavement, which consists of a lightweight aggregate and a highly modified asphalt binder compound. The composition is formed by heating the binder to a fluid state and mixing it with the light aggregate and then allowing it to cool in its solid form. The composition for pavement patches is used to repair holes in the pavement, such as potholes, cracks and depressions. It is applied by heating the composition in a solid state until obtaining a fluid state and applying it in depression or on a surface that needs repair and then allowing it to cool. The resulting patch is self adherent, strong and flexible. The composition formulation can be adjusted for specific use in a cold climate, a moderate climate, a warmer climate, or for use in various traffic applications.

Patent document No. US6844418 refers to an improved polymer additive that can be used to increase the viscosity of an asphalt at high temperature, without negatively affecting the low temperature viscosity of the asphalt. The additive can also be used to improve the stiffness of certain asphalts. The additive is produced from mixtures of polymers available by a thermal process. The invention further provides a better polymer modified asphalt. In its preferred version, the invention also provides an ecologically acceptable method for recycling post consumer plastic bottles and carpets.

Some studies and developments have focused on the application of the asphalt mixture. So for example patent document number US6109826 shows a material fusion equipment and an applicator for liquefied pavement material on damaged pavement. The applicator reduces the problems that occur due to the involuntary solidification of the pavement materials inside the hose, whether they are of the heating type or without heating. A cabinet is included, which is able to maintain the temperature of the hose without heating during periods of inactivity. In addition, an access port allows any type of hose to run continuously, directing the material back to the feed container. There is also a chimney that ventilates the combustion by-products generated during the fusion of the paving material. This chimney is coupled to the container that contains the paving material, so that harmful vapors produced during the fusion are extracted.

Asphalt concrete is used to cover road gaps that includes 5 to 20% granular plastic to complement the asphalt binder. According to the patent application No. US201 10070025, the hole punching is carried out by means of a vehicle that has the patching system mounted to fill cracks and holes in pavements and the method for its use. In this document, the mixture is incorporated into the hole by washing the emulsion feed lines; in parallel, the area to be regenerated is cleaned with air, followed by the injection of the previously heated emulsion to maintain a temperature of the order of 135 to 160f. This feeding is carried out under the control of valves in four adjacent positions in order to completely cover the affected area. The materials with which the equipment is made, must be resistant since the injection of the solution is carried out at high temperature and pressure conditions.

This equipment incorporates devices for the extraction and washing of asphalt emulsion from the feeding lines of the patching equipment. This equipment completely recycles the cleaning agent used to purge the feed lines, as well as eliminate any external discharge of potentially toxic materials. A cleaning agent is used to purge the feed lines. The emulsion is collected in a tank of recovery and combined with fresh emulsion delivered from a storage tank when the collected emulsion reaches a certain concentration. There are also electrical controls for the operation of two motors with a single power supply that employ cam switch matrices and a polarized diode array to avoid power feedback from the power source and ensure valve positioning accuracy multiposition to perform the determined operation.

It can be seen that in the state of the art there is no injection patching technology that describes the use of post-consumption polymers with asphalt solution in different proportions to be applied at different times of the patching process. Likewise, there is no technique to improve the fixation of the asphalt molecules to the polymer surface and the fixation of the mixture in the hole to avoid deterioration in key areas such as the edges of the hole.

Description of the Invention

The present invention relates to a technology for obtaining an asphalt mixture composed of polymeric material (PET, HDPE, PEBD among others) post-consumption, asphalt solution, aggregates (stone) and plant fibers, to be incorporated into the hollows of a highway permanently by means of an injection patching method. To reduce the presence of gaps in the tracks, patching and patching activities are commonly carried out (specific conservation operation whose purpose is the elimination of cavities produced in the pavement and irregularly firm and different sizes), using asphalt as raw material . This represents a higher expenditure of resources than those that would have been generated in an adequate road maintenance plan.

It is for this reason, that it is intended to implement an alternative to solve the growing problem of presence of holes without resanancing, focusing on the transformation of post-consumer plastics into material Asphalt alternative giving it an added value, this being an environmentally responsible solution, economically efficient and of technical scope both in its production and in its use. Currently, plastic has become one of the necessary supplies for daily life, however, it still has many recycling problems, particularly due to the difficulty of identifying the wide range of plastic resins in the market, which would allow its post-consumer and post-industrial management.

Within the methods of use of plastic is the transformation into asphalt. This process allows to obtain a high economic benefit and simultaneously solves the problem of the disposition of mixed plastics. These benefits are received by both the Industry, with a more economical asphalt mix, as well as the community and government organizations, with a reduction in landfill occupancy and environmental impact.

Polymer modified asphalts increase the life of a pavement two to three times with an additional cost of up to 25% on the asphalt mix. Conventional asphalts have satisfactory mechanical and adhesion properties in a wide range of applications and under different climatic and traffic conditions. However, the increasing increase in traffic volume and the magnitude of loads, and the need to optimize investments, causes, in some cases, the properties of conventional asphalts to be insufficient. For example, with conventional asphalts, even with the toughest grades, it is not possible to eliminate the problem of deformations caused by channeled traffic, especially when high temperature conditions have to be faced. In addition, with the simple adoption of harder asphalts the possibility of flsuraclones caused by thermal effects is increased when temperatures are very low.

Likewise, conventional binders do not provide sufficient mechanical strength due to insufficient cohesion and adhesiveness, which together with the low binder content of these mixtures could result in a decrease in their durability. Similarly, the new layers Thin surfaces would be less durable when they are subjected to high traffic intensities. In these situations, the best solution is to modify the asphalt to give it the characteristics of fixation, elasticity and resistance suitable for the worst traffic and environmental conditions. It can be found that the adoption of modified asphalts has several advantages such as: decreased susceptibility to load application times; increased resistance to permanent deformation and breakage in a wider range of temperatures, stresses and loading time; increase of mechanical resistance; high tensile strength; good wetting power; and adhesion the aggregates.

Further:

The elastomeric polymer is compressed by applying an effort, but regains its original shape upon removal. More flexible mixtures are obtained at low operating temperatures reducing cracking.

Asphalt exudation decreases: due to the higher viscosity of the mixture, its lower tendency to flow and its greater elasticity.

Greater elasticity: due to long chain polymers.

Greater adhesion: due to short chain polymers.

Greater cohesion: the polymer reinforces the cohesion of the mixture.

Better workability and compaction: by the lubricating action of the polymer or the additives incorporated for mixing.

Better waterproofing: in bituminous seals, it absorbs tangential stresses better, preventing the spread of fissures.

Greater resistance to fuel spillage.

Reduces the noise level: especially in open mixes.

They do not require special equipment.

Decrease thermal susceptibility.

They reduce fragility in climates and increase cohesion in hot weather.

Vary their behavior according to the temperature they are in.

Elastomers are deformable at room temperature. The cost depends basically on its polymerization process and the availability of the monomers.

Easily available in the market.

Asphalts modified with elastomers are damaged by crushing or abrasion of the aggregate rather than by the failure of the binder (asphalt).

The elastomeric polymer provides excellent aging resistance.

Improves the shelf life of mixtures: less conservation work.

Improve adhesion to aggregates.

They improve behavior both at low and high temperatures; since the main effect of adding polymers to asphalts is the change in the viscosity-temperature ratio.

Greater plasticity interval.

Modifying an asphalt with a compatible polymer quickly produces a stable asphalt using conventional preparation techniques.

The properties of the product are not affected if it is stored at room temperature for prolonged periods.

They allow greater thickness of the asphalt film on the aggregate.

Most polymers are based on a carbon skeleton, so they are organic materials.

Using polymers in asphalts has changed the properties of the asphalt layer; which has allowed the addition of new asphalt properties, improving their characteristics. Each polymer adds a different property to asphalt according to the purpose of the pavement since the choice of polymer depends on circumstances such as traffic, temperature, type of terrain, etc. The use of polymers in modified mixtures does not alter the procedures normally used in the works of paving. It has also shown benefits in countries of Europe and the United States; despite the increase in the initial cost in asphalt cements.

The process of repairing deformities or gaps in the tracks comprises a stage to prepare the hole in which the trash and dust is removed from the surface, and then heated to receive a first layer of asphalt emulsion This first layer is made up of asphalt that can comprise a small proportion of polymers (between 5 and 15%). This layer is placed in order to cover the hole, improving the adhesion of the asphalt that will later fill the hole. The first asphalt layer can be applied by a spray method, which is why the mixture must be heated and must have a high elastic modulus so that it can flow through the spray medium such as a hose or a flute. Once the asphalt emulsion layer is deposited, the modified asphalt mixture is deposited. The deposition of this second asphalt layer is done by gravity until the hole is completely filled. The mixture must be kept warm in order to improve its ductility, since it is convenient to keep the polymers warm during the deposition of the material, not only so that the mixture remains in a fluid state, but also to improve the adhesion of the asphalt to the particles of polymer.

Finally, the repair is completed by compacting the mixture either by a gravity compaction process, or a compaction using a tandem roller. The latter technique is advisable as it helps level the surface of the patch with the road or traffic surface.

The asphalt material used comprises a mixture of modified asphalt solution with an asphalt additive dissolved in the material, which consists of 15% dissolved polymer, an aggregate such as stone, and natural fiber such as broom (Spartiumjunceum L.) or phyche (Andean Furcraea). The fiber forms a coating that helps fix the asphalt and also helps to bind the asphalt molecules at the edges of the hole preventing the patch from deteriorating in these places.

To form the material, the unrefined product is poured into a container such as a hopper from an asphalt application plant. Then the equipment is located and placed in motion, to then add the polymer to dissolve and the other additives such as fiber. To this end, the plant is usually provided with an open turbine.

The equipment has a mixing head that works according to the principle of injection, and includes clamping means, stirrers and solvents. With these stirrers the total action is limited to the mixing or recirculation of the liquid or some solution. The mixing cycle comprises:

Place the materials at the bottom of the work head. The mixing action is produced by the high-speed rotation of the leaves in the enclosed space.

During the ejection from the work head, the rotor blades hold the material to an intense cutting action, which guarantees a fast and total cutting and dissolution process. The emulsifying mesh or the disintegrating head assists the process, dissolving agglomerates, removing large particle sizes so that it produces homogeneous emulsions and dispersions in minutes.

The processed materials are then shipped with great force and speed within the body of the mixture. At the same time the new material enters the base of the mixing head. This entry and exit of the mixtures indicates a circulation pattern which will depend on the size of the tank and the type of head or equipment used. The total of the mixture passes through the mixing head hundreds of times during the process and the combination of the three stages of the cycle results in a positive, controlled and efficient mixing.

The asphaltic additive used to enrich the mixture, consists of a polymeric material (PET, HDPE, PEBD among others) post consumption, which has an irregular shape, such as an agglomerated crispeta. A plastic agglomerator is used to make the polymer. For this, flexible polymer (in sheets) is added to the machine and it is rotated at high speed. The friction of the blades of the agglomerator against the plastic material, causes the temperature to rise forming a hard paste. To increase the modulus of elasticity and lower the temperature, add water, then the material is cut by means of the blades and this takes the desired shape, in this case an irregular shape.

The relevant aspects and advantages of the present invention will be better understood in relation to the following figures.

Description of the Figures

Fig 1. Patching procedure of an open cavity on the surface of a track. Fig 2. Composition of the asphalt mixture and final arrangement on the surface of the hole.

Fig 3. Irregular isometric view of the aggregate polymer.

Detailed description of the invention

Road infrastructure is an aspect of vital importance for the development of a country, so it is necessary to provide adequate maintenance to extend its useful life. For this reason it is important to solve irregularities that form on roads such as holes or cracks. There are different treatments, among which is the use of hot or cold asphalt mixtures.

The use of modified asphalt cement is a technique used in several countries in order to take advantage of asphalts in paving roads. This consists in the addition of polymers to conventional asphalts in order to improve their mechanical characteristics; that is, its resistance to deformations due to weather and traffic factors (vehicle weight); In addition, they increase the adhesion at the interface between the stone material and the asphalt material, while still retaining it in the presence of water. These mixtures increase the resistance to deformation, to the stresses of repeated tension and, therefore, fatigue, reduce cracking, as well as the susceptibility of asphalt layers to temperature variations.

Figure 1 shows the process of repairing a deformity in a path using the material manufactured according to the process of the present invention. In this case, a traffic surface (1) has a slope or gap (2) which can be caused by multiple causes such as excess weight, climatic changes, water filtration, blows and so on. The first stage in the deformity repair process is to prepare the hole by cleaning and removing all the accumulated waste inside it. The second stage consists in applying an asphalt emulsion layer (3) for which the hole must be previously heated. This layer (3) is formed by asphalt that can comprise a small proportion of polymers (between 5 and 15%).

As can be seen, the layer (3) forms a coating on which the modified asphalt applied in the next stage can be more easily adhered. The asphalt layer (3) can be applied by a spray method with hose or a flute, which is why a high elastic modulus that allows the material to flow through such mechanisms must be ensured.

Then, the modified asphalt mixture (4) is deposited by gravity. The modified asphalt mixture (4) is obtained from a mixing cycle that is carried out in a mixing head that works according to the principle of injection.

For this purpose the unrefined product is poured into a container such as a hopper of an asphalt application plant. The equipment is then placed and placed in motion, to add the polymer to be dissolved and the other additives such as fiber and aggregate (rock). The mixing cycle comprises: Place the materials at the bottom of the work head. The mixing action is produced by the high-speed rotation of the leaves in the enclosed space.

The hollow repair process is completed by compacting the mixture either by a gravity compaction process, or by compaction using a tandem roller.

Figure 2 shows in detail (5) the composition of the modified asphalt mixture (4). The asphalt material used comprises a mixture of asphalt solution (6) formed by binders that are found in various ways in nature in its pure state or with a matrix of thick or fine stone aggregates, or they can be asphalt produced by man from oil distillation process in a refining plant. The asphalt solution (6) contains an asphalt-dissolved additive dissolved in the material, which consists of 15% dissolved polymer (7). This consists of a polymeric material (PET, HDPE, PEBD among others) post consumption, which has an irregular shape, such as an agglomerated crispeta. The polymer has a regular size with a maximum diameter of about 5mm. The shape of the polymer allows greater adhesion of the asphalt solution (6) since it accumulates on the Irregularities arranged on the surface of the polymer (7). Figure 2 shows this effect with a greater accumulation of material in the Irregularities of the polymer. To give stability and greater consistency to the mixture, an aggregate material (8) is used. In this case, stone was preferably used. Likewise, natural fiber (9) such as the broom (Spartiumjunceum L.) or the fique (Andean Furcraea) was added to the mixture. The fiber forms a coating that helps fix the asphalt and also helps to bind the asphalt molecules at the edges of the hole preventing the patch from deteriorating in these places.

Figure 3 shows the shape of a polymer particle (7). As can be seen, the polymer comprises a solid central body (10) of post-consumption material, and a series of Irregularities (1 1) arranged on purpose to create anchoring surfaces for the asphalt solution (6). In this way, the asphalt material produced comprises the advantages of modified asphalts, but presents greater advantages in terms of fixing the asphalt and anchoring it, so that a stronger and more durable repair is obtained.

It is not considered necessary to make this description more extensive so that a person skilled in the art understands the scope and advantages of the invention. All the technical and scientific terms used here have the same meaning as those of ordinary skill in the art understand them.

Claims

A modified asphaltic material to repair paved traffic surfaces characterized in that it comprises:

a mixture of asphalt solution (6) of natural or man-made asphalt binders, where the asphalt solution (6) contains:

an asphaltic additive dissolved in the material, which consists of 15% dissolved polymer (7), the dissolved polymer (7) corresponds to irregular particles in the form of agglomerated crisp of post-consumer polymeric material, which can be selected from the group that It consists of PET, HDPE and PEBD;

an aggregate material (8) that can be stone or rock, and

a natural fiber (9).

A modified asphaltic material for repairing paved traffic surfaces according to claim 1, wherein the surface of the polymeric material comprises irregularities with a maximum particle size of 5mm in diameter.

A modified asphaltic material to repair paved traffic surfaces according to claim 1, wherein the dissolved polymer (7) is obtained by a plastic agglomerator from post-consumer polymeric material in the form of a sheet.

A modified asphaltic material for repairing paved traffic surfaces according to claim 1, wherein the natural fiber aggregate (9) is a fiber selected from the group consisting of broom (Spartiumjunceum L.) and fique (Andean Furcraea).

A method for repairing a paved surface from a modified asphaltic material, the method comprising:

a) Prepare the hole by cleaning and removing all the accumulated waste inside it;

b) Preheat the surface to be repaired; c) Apply an asphalt emulsion layer (3) by means of spray with hose or a flute;

d) Deposit by gravity the modified asphalt mixture (4);

e) Compact the mixture by gravity compaction, or compaction using a tandem roller.

A method for repairing a paved surface from a modified asphaltic material according to claim 5, wherein the asphalt emulsion layer (3) is formed by asphalt comprising a small proportion of polymers between 5 and 15%.

A method for repairing a paved surface from a modified asphaltic material according to claim 5 wherein the modified asphaltic mixture (4) is prepared by the method comprising:

a) Place polymer aggregates, fiber and asphalt solution at the bottom of a work head;

b) Mix the materials by rotating at high speed the leaves in the closed space;

c) Produce a homogeneous emulsion, dissolving agglomerates and removing large particle sizes;

d) Expel the mixture with force and speed inside the body, establishing a circulation pattern depending on the size of the tank and the type of head or equipment used.