EP2511420A1

EP2511420A1 - Road strengthening and reinforcement during a recycling process

Info

Publication number: EP2511420A1
Application number: EP11162603A
Authority: EP
Inventors: Tony Duffy
Original assignee: Tony Duffy Engineering Ltd
Current assignee: Tony Duffy Engineering Ltd
Priority date: 2011-04-15
Filing date: 2011-04-15
Publication date: 2012-10-17
Also published as: EP2697434A1; US20140270953A1; WO2012140198A1; RU2013150983A

Abstract

The invention relates to an optional additional process during routine rehabilitation or recycling of road surfaces. More particularly, the invention relates to a process whereby a geomaterial, whether mesh, membrane, textile, grid or fabric membrane is placed underneath in-situ road surface material, which has been loosened as part of a regenerative or recycling process, as an added structural benefit to the rehabilitated road structure.

Description

Field of the Invention

The invention relates to an optional additional process which can be employed during routine rehabilitation or recycling of road surfaces. More particularly, the invention relates to a process whereby a geomaterial, such as mesh, membrane, textile, grid or fabric membrane, is placed underneath in-situ road surface material, which has been loosened as part of a regenerative or recycling process, as an added structural benefit to the rehabilitated road structure.

Description of Related Art

Road and pavement surfaces typically comprise structural layers of compacted materials (often called roadbase) on a compacted subgrade (often called formation level), covered by a friction layer. A friction layer is typicallysubstantially non-structural and is often made up of one or more surface dressing layers, which acts as a water-resistant protective layer with skid resistance. Subgrade is the in-situ native material upon which the road or pavement structure is placed or constructed at selected location. Subgrade is typically then formed of non-bound material. A subgrade that can sustain a high degree of loading without an excessive deformation is considered good quality. Structural layers placed above the sub-grade typically consists of aggregate such as natural gravel or stone (both crushed and uncrushed) and other granular materials, bituminous macadam base, hydraulically bound macadam or treated base, including treatment with lime, cement or bituminous binders. As the structural layer(s) lie immediately beneath the friction layer and upon the subgrade, it is the part of the road construction which imparts most integrity to the overall structure and may be considered to be the part of the structure subjected to most intense loading. Therefore, to maximise road service lifecycle, the structural materials must be of very high quality and great care should be taken during its construction. The friction course, making up the top layer of the road or pavement, is the part of the road structure which forms the driving surface and is in direct contact with the vehicle wheels and typically constitutes materials comprising bitumen binders.
The subgrade must be able to receive without deflection loads transmitted from the road or pavement surface through the structural pavement layers. Where the subgrade is weak (which is usually the case with clay subgrades and/or soils that have a significant clay content), it is generally necessary to have a capping or fill layer over the subgrade to increase the subgrade bearing strength before the actual road pavement thickness required can be determined.
Critically, the strength of the subgrade will be maintained or even increased by good drainage with bad drainage weakening an otherwise good subgrade. The primary function of the road base structural layers is to sustain and spread the traffic load sufficiently during transfer downwards to the subgrade formation. The subgrade load bearing capacity is frequently affected by factors including the types of soil, moisture content, and degree of compaction. If the road base structural layers becomes water saturated, the load can not be dissipated to the underlying subgrade in an effective manner; such saturation can occur either from rising water from the subgrade or downward ingress from a friction course which has become pervious. Therefore, free draining subgrade is considered the best while peat type is considered as the poorest type of subgrade material in order to both maximise subgrade strength and minimise water transfer to the roadbase structural layers above.
As before, the structural pavement layers also intercept upward movement of water (by capillary action) and acts as a separating layer between subgrade and the non-structural road friction course such as surface dressing. This serves to also prevent contamination of the friction course by upward movement of the sub-grade through the friction course, thereby compromising the road or pavement integrity.
Road surfaces deteriorate over time as a result of continuous damage resulting from traffic, and more significantly, from environmental stresses, which include thermal stresses such as freeze thaw cycles and cold and heat extremes, together with natural deterioration resulting from aging and crushing in-situ. For instance, some clay soils can shrink and swell depending upon moisture content, whereas soils with excessive fines may be susceptible to frost heave in freezing areas.
Virtually all roads require some form of maintenance before they come to the end of their service life. Weathering and heavy use can loosen chippings and cause road surfaces to become worn, which increases the risk of vehicle skidding. Typical damage includes cracking, pothole formation, surface water ponding and more seriously water infiltration. If the water-resistant protective road surface dressing becomes compromised or becomes loosened, further problems, such as cracking and potholes, are likely to occur, depleting and/or destroying the integrity of the structural layers through downward moisture ingress.
Cracks are mainly caused by weather and stress from heavy use or movement of the subgrade and, if left unrepaired, can allow water into the matrix layers below the road surface causing further damage, such as potholes. A pothole results where the surface of the road or footway has failed and a hollow has formed. Potholes worsen with heavy road use and can often damage the structure of the road matrix below the surface layer. Accumulating water results in ponding on the road surface. Surface water (ponding) occurs when water cannot drain. Ponding is often caused by poor drainage, usually because the drains are blocked or are not fit for purpose, or because the road does not have sufficient slope or camber to allow water to runoff. If left untreated, surface ponding can widen cracks and contribute to the development of potholes and other damage. Spillages, residues from motor engines and farm effluent are also problematic being particularly aggressive to bituminous surfaces and over time can degrade the friction course, making the surface more susceptible to the types of damage discussed above.
Water infiltration causes the most serious damage, particularly in cases where drainage is poor. Typically, road surface drainage occurs across the (veneer) friction course on top of the shaped structural road base layers to an installed drainage system, for example, French drains or a road side ditch. However, if the drainage system is poor or not operating correctly, the water can infiltrate and rests within the road, where repeated vehicle loading can quickly lead to failure as the vehicle load is no longer transferred correctly to the underlying supporting subgrade. For surface dressed roads, aggregates have a greater affinity for water than they do for their bitumen coating. In the presence of water and movement of the aggregate, the binder film on the aggregate particles can become compromised and water can contact with the underlying structural layers which are often of unbound or hydraulically bound aggregate composition. The broken down binder is stripped off the aggregate particles over time and the protective impervious layer is substantially washed away rendering the surface more prone to water infiltration.
As the water table rises and falls, for example seasonally, it is clear that good drainage is essential to facilitate the minimisation of seasonal variations in the water table and thus keep the risk of water infiltration and flooding low. When water enters a road structure, water damage is initially caused by pressure from vehicles passing over the road putting stress on the water present in the road pavement. This pressure forces the water further into the core of the road matrix where more damage is caused. The water infiltrates into the structural layers and even the subgrade layer below the road structure weakening the entire road structure. Furthermore, once the surface integrity has been compromised and water enters the road structure, over time the moisture content of the road structure increases with a simultaneous reduction of the road strength, either of individual layers or as a composite structure. The process eventually leads to weakening and failure of the road. The effect can be accelerated under action of freeze thaw cycles in which frost heave occurs. This involves freezing from the surface downwards, which results in water being drawn up from the lower levels. Subsequent layers of ice are formed which cause the road to expand upwards. Water that has entered the road pavement and is subject to the process of freezing (expansion) and thawing during the winter also brings about the swift failure of the road pavement. Not surprisingly, good drainage helps prevent frost heave and frost damage. If the water table below the road or pavement is allowed to rise up into the road matrix construction layers, water can be imbibed into the core of the matrix (facilitated by capillary action). Likewise, if water resting on the surface dressing is not prevented from entering the road or pavement matrix by means of an impervious binder course (for example, bitumen based surface dressing) or a completely impervious bond coat, the water will weaken the road structure and may eventual lead to road failure of the type discussed above.
Hot mix road recycling trains for recycling asphalt and wearing course bituminous macadam have been available for quite some time, but are involve high cost operations and are generally only suitable for wide primary road and motorway type projects covering large areas. Such trains are not at all suited to smaller regional and local roads which have not been designed and constructed to a specific design specification. Such roads can vary greatly in thickness and may be built up from layers of pit run, gravel, broken stone or hydraulically bound macadam. Such roads are typically maintained by repeated rounds of surface dressing replacement of the friction course and by occasional deepening and strengthening of the structural layers prior to new surface dressing. Where road or pavement drainage is poor, for example, on regional, local or indeed rural road networks (where drainage of the road surface generally involves poorly maintained ditches adjacent to the roadway) the problems are compounded. Generally, cost and indeed access can limit the type of repair work that be carried out. It would be difficult and costly to build new roads in these situations. Such roads are typically maintained by periodic use of subsequent layers of surface dressing, rather than correction of the fundamental factors leading to the problems. Excessive water infiltration can result in lifting of this top dressing leading to a failed friction course where the required repairs have to be repeatedly implemented.
Geomaterials have been used for strengthening, reinforcing, and as water barrier thereby extending the lifetime of roads and pavement. Geomaterials are also used to improve soil conditions for a number of applications. They typically but not exclusively take the form of a sheet of flexible material such as manufactured polymeric or glass fibre or textile or other fabric materials. They are typically used in contact with soil materials or pavements as an integral part of the road or pavement matrix. The most common applications in general use are in pavement systems for both paved and unpaved roadways, for reinforcing embankments and foundation soils, for creating barriers to water flow in liners and cutoffs, and for improving drainage. They generally serve to advantageously increase the load-bearing capacity and lifespan of roads and pavements. Geotextiles are usually classified by their manufacturing process as either woven or non-woven, spun, moulded etc as appropriate to their constituents and nature of the finished material required (impervious fabric or pervious grid etc). Depending on the geomaterial selected, they offer benefits with regard to filtration beneath aggregate sub-base for paved and unpaved roads, as drainage interceptors for horizontal flow, as separator (of dissimilar materials) between subgrade and structural pavement layers in paved and unpaved roads or between subgrade/old pavement layers and new asphalt layers and act as a reinforcement (of weak materials) over soft soils for unpaved roads, paved roads, airfield, railroads, construction foundations.
Geomaterials are commonly used for the retardation or prevention of water movement for example vertical movement. Suitably then they acomprise continuous sheets of low permeability materials. Using a geomaterial to separate the subgrade from the roadbase by laying a membrane between these layers strengthens the road base by preventing layer contamination resulting from sub-base mixing with sub-grade. Furthermore, such membranes limit damage caused by water infiltration, in addition to preventing surface water pooling. Bitumen coated membranes provide a waterproof layer which can protect the road structure from water infiltration and the resulting damage and weakening of the road. Geotextile membranes provide the drainage, separation and reinforcement required to stabilize the base of roads on soft subgrade. Many geomaterials are specifically for strengthening road as reinforcement acting in conjunction with the structural roadbase layers. These tend to be of the grid variety (with overlapping oriented structural elements) in order to generate friction with surrounding aggregate and providing for load transfer. Where this is used, the total road strength can be increased or the depth of required roadbase structural layers can be minimised, thus reducing the weight of the road, primarily where subgrade is very poor and susceptible to shear failure.
Road and pavement cold asphalt regeneration technology methods (for example road trains) are desirable since they recycle road surface materials avoiding use of virgin materials. Re-using existing road binders where present provides an environmentally and economically favourable solution to the problem of road or pavement regeneration as land fill/waste issues are eliminated or at least reduced as well as significantly reducing the embodied carbon content of the renewed pavement.
Cold regeneration technology for pavements and roads are known. Existing methods and apparatus for carrying out same involve milling the existing road surface, lifting the loosened surface and treating it with chemicals to produce a foamed or otherwise stabilised asphalt cold regeneration layer which is then put down on the original surface and processed to form a regenerated road or pavement surface. Many of the known apparatuses for cold road recycling are large, high cost machines which are inherently unsuitable for smaller regional, local and rural roads. Furthermore, if a geomaterial is required, it can only be laid after the road-lifting step. Therefore, where the structural improvement offered by the incorporation of a geomaterial is desired, the process is slow, time-consuming and thus expensive, as the membrane can only be laid when the old road surface is completely removed. Road rehabilitation can only then occur when the geomaterial laying step is complete. This means that there are often disruptive long-term closures while these additional roadworks are taking place.
Thus, it is desirable to provide an improved process and an apparatus for the placement of such a geomaterial for use during such road rehabilitation or recycling works which is capable of using the existing road materials. An apparatus or process relating to same would advantageously allow in-situ cold road regeneration in a fraction of the time currently required for carrying out this operation, with cost efficiencies, improved safety for workers, increased road service life, reduction in maintenance cost for years, minimising traffic disruption associated with road closures for regular maintenance roadworks.

Summary of the Invention

According to the present invention, as set out in the appended claims, there is provided a process for in situ insertion of a geomaterial underneath a loosened road or pavement surface material comprising the steps of:

(i) lifting at least part of the loosened material to leave at least part of the road base or road subgrade exposed;
(ii) laying a geomaterial onto the exposed road base or road subgrade;
(iii) optionally treating the lifted material with at least additive; and
(iv) relaying the treated material to a predetermined profile on top of the geomaterial,

The skilled person will appreciate that loosened road or pavement surface material may comprise any uncompacted road base material. It will be further appreciated that the loosened road or pavement surface material may be hot, cold, hydraulically, cement or bitumen bound. The present invention thus allows for lifting of the in-situ road materials, simultaneously laying a geomaterial underneath the loosened and lifted site won materials and relaying the site won materials to an designed road profile over the geomaterial in a one-pass process. This is an extrememly efficient process that allows for geomaterial installation.
In a preferred embodiment, the lifted loose road or pavement surface material may be treated with at least one additive, chosen to enhance particular mix attributes, to a pre-selected dosage using a calibrated or metered dosing arrangement.
The skilled person will appreciate that the term "geomaterial" is deemed to include all suitable materials, typically in the form of a flexible sheet and including materialsfrom geogrids to water proof membranes. Suitably, geotextile membranes are one example of the preferred type of geomaterial, but also included are mesh, membrane, textile, grid or fabric membrane. Preferably, the geomaterial will be specially chosen for desired attributes, whether as a water barrier or layer maintenance or as a structural reinforcement, with the appropriate strength, shape and form for site specific application, including expected traffic loading as part of a road design process.
In a preferred embodiment, step iv may be followed a pre-compacting step. It will be appreciated that this pre-compacting step may be carried out by any suitable compacting apparatus such as a paving apparatus or other equivalent machinery.
Thus, the invention concerns a highly efficient process for road rehabilitation where a geomaterial is desired. Thus the process of the invention comprises lifting a loosened surface, with the optional addition of materials such as water or other additive to the lifted material in a calibrated or metered fashion, while simultaneously laying a selected geomaterial, for example on the exposed road base or subgrade surface, redepositing the lifted or site won material onto the top of the geomaterial, with some compaction of this resulting profile.
The process is advantageous over prior art method of geomaterial placement in that the process has been highly streamlined so that significant time and cost savings can be made by facilitating this step in a single pass operation, thus obviating the need for distinct stages in the works usually associated with geomaterial. Significant road closure time is avoided.
Preferably, as much as possible of the loosened road or pavement material is lifted. However, it is normally preferred that none of the clay or soil subgrade material is lifted. Typically, the depth of loose material to be lifted is in the range of 60 to 200mm.
While compaction, typically minor compaction, may occur after step (iv), the relaid treated road or pavement material may be compacted after step (iv). Thus, in a preferred embodiment, on-site compaction is carried out after step (iv) by compressing the regenerated surface in a traditional post-paving process by any suitable machine or device known to the skilled person, for example, a static or vibrating compactor device.
The compacted road base may be topped with a friction course, typically comprising a suitable surface dressing, such as a bituminous sealing layer, for example.
In a related aspect, the invention provides an apparatus for carrying out the process of the invention. The apparatus of the invention allows the above strengthening process to be carried out in-situ in a single pass fashion. For example the apparatus may be a suitable road train of machinery.
Advantageously, the apparatus of the invention may be easily added into existing in-situ recycling processes or machinery for carrying our same (for example involving a continuously moving train of machinery) to save time and cost by deriving the benefit of the one pass action. Thus existing processes may be easily adapted to include the apparatus of the invention so that the benefits described herein can be obtained. Existing processes and machinery can thus be easily integrated resulting in a more efficient and cost effective road rehabilitation and/or strengthening process.
In a related aspect there is provided an apparatus for in situ insertion of a geomaterial underneath a loosened road or pavement surface material, the apparatus comprising a frame, onto which is mounted:

(i) means for lifting loosened material from the road or pavement surface to expose road base or road subgrade surface, said means being provided at the front of the apparatus;
(ii) means for laying a geomaterial onto exposed road base or road subgrade surface;
(iii) means for relaying the material to a predetermined profile on top of the geomaterial,

Preferably, the apparatus of the invention further comprise means for transferring the lifted material to a reservoir for storing and/or treating the material. The reservoir is for holding the lifted loose material and any necessary additives that may have been incorporated into the material in the reservoir. In a preferred embodiment, the reservoir for the lifted loose material is a modified hopper of a paver machine. In other words, in this embodiment, the apparatus connects to the front of a modified paver and integrates completely with same to a pre-determined design, based on the adapting the original paver specification.
Suitably, the reservoir is preferably a hopper from a paver machine or other equivalent apparatus (to which the apparatus may be attached). Thus in a preferred embodiment, the apparatus is mountable, for example comprises means for mounting the apparatus, onto the front of a paver machine for depositing and compacting the stabilized material on the membrane provided on the exposed road base or road subgrade surface. Such means include use of brackets, hook or other connecting arrangements known to the person skilled in the art. Thus, the invention relates to an apparatus for attachment to a self-propelled, multi-part machinery such as a paver or a road train device. Advantageously, the apparatus may then utilise the hydraulic, mechanical and electrical outputs of the paver or the like. In a related aspect the apparatus can be used in a discreet machine suitable for carrying out all aspects of the inventive process described above.
Suitably, the apparatus of the invention further comprises means for adding water or at least one other additive onto the lifted material and/or the reservoir. Desirably, the additive is sprayed onto the lifted material while being transferred or while stored in the reservoir. Spraying is the preferred adding means, a spray bar for example, provides efficient means of spraying water and/or additives.
In a preferred embodiment, the apparatus further comprise means for transferring the lifted material from the reservoir to the rear of the apparatus so that the lifted material may be relaid on top of the geomaterial. Suitably, means for depositing and/or pre-compacting the material relaid on the geomaterial is also included.
In a preferred embodiment the apparatus of the invention, the apparatus further comprises means for transferring the lifted material from the reservoir to the rear of the apparatus so that the material may be relaid on top of the geomaterial. In a preferred embodiment, the apparatus further comprises means for depositing and/or lightly pre-compacting the material relaid on the geomaterial provided on the exposed surface.
In a preferred embodiment, the apparatus of the invention, the means for lifting the loosened material from the road or pavement surface comprises a feeder assembly comprises means for forming a directed flow of lifted loose material. Suitably, the feeder assembly is mounted onto the front of the apparatus. The feeder assembly may comprise a cutting edge that transfers material to the transferring means.
Preferably, the means for transferring the loosened lifted material to the reservoir for the lifted loose material is a conveyor means, preferably, an endless conveyor belt, for example.
Preferably, the conveyor comprises a sprocket and chain conveyor with laterally disposed slats to facilitate lifting and transferring the loosened material from the cutting edge to the reservoir. Suitably, the slats are of steel or other suitably hard and wear resistant material.
More preferably still, the apparatus of the invention further comprises means for directing the lifted material. Suitably, the means for directing the flow of lifted material comprises horizontally actuatable side blades or arms located on opposite sides of the feeder assembly. Desirably, the blades or arms are provided in a pair, one of each on opposite side of the feeder assembly. Preferably, said side blades or arm extend forward in front of the feeder assembly. The hydraulically actuatable blades or arms are suitable for adjusting the width of the directed flow to a predetermined level. This facilitates feeding material which is outside the scope of the lifting means into the correct position for optimised uptake and lifting.
The feeder assembly may further comprise a cutting edge which transfers material to the transferring means.
In a preferred embodiment, the apparatus further comprises calibration or metering means for measuring the amount of lifted material to be treated with additives. Said calibration or metering means may be provided on the transferring means.
In a preferred embodiment, the apparatus of the invention comprises means for laying a geomaterial onto exposed roadbase, subgrade or other surface comprising a supply of geomaterial adapted to be delivered onto receiving surface by forward movement of the apparatus.
Preferably, the supply of geomaterial comprises a roll of membrane mounted on the apparatus. Desirably, the supply is provided on the underside of the apparatus. Suitably, the geomaterial supply is achieved by the forward motion of the apparatus or the paver onto which the apparatus is mounted.
Suitably, the means for laying the geomaterial further comprises a spooling means and tensioning means for controlling the tension on the geomaterial.
In a preferred embodiment, the apparatus of the invention comprises means for adding water or other additive to the lifted material while on the transferring means, the conveyor. Desirably, said means comprises a spray bar provided above the conveyor or at the top of the conveyor.
In a preferred embodiment, the apparatus of the invention further comprises storage means for holding the water or other additive until required for use. Suitable storage means include tanks provided on the apparatus or otherwise connected to the apparatus.
In a related aspect, the invention relates a paver machine comprising the apparatus of the invention.
Apparatus of the invention may be used in existing hot mix and cold mix trains and processes involving same.
The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Brief Description of the Drawings

The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 illustrates a schematic drawing of an apparatus of the invention mounted onto the front end of a paver machine in use;
Figure 2 & 3 illustrate top perspective views of the front of a prototype of the apparatus of the invention;
Figure 4 illustrates a top perspective view of one side of a prototype of the apparatus of the invention; and
Figure 5 illustrates a perspective view of the top of a prototype of the apparatus of the invention.

Detailed Description of the Invention

Referring now to the drawings and specifically Figures 1 to 5 inclusive and initially Figure 1. Figure 1 shows an apparatus of the invention generally by reference (R) mounted on to the front end of a paver machine, hereinafter called a paver (P). The paver can be of the type in the 15 ton and over classification, which can be on multi drive wheels or tracks. The paver machine used should have at least 4 metre screed length with tampers for compacting (not shown here). Apparatus (R) is mounted mechanically onto the front of an existing paving machine (P) and is powered hydraulically, mechanically and electrically by the paver (P). The apparatus of the invention comprises a cutting edge (1), augers (2), conveyor or elevator arrangement (S) and metering device (4), all of which make up the collecting head (H) which lifts loosened material (A) in the path of the paver (P) onto the conveyor arrangement (S). A membrane dispenser (G) is located beneath the cutting edge (1) and conveyor arrangement (S). A spool (5) of membrane (B) is positioned on the membrane dispenser (G). Tensioning arrangement (7) is in contact with the spool (5). The membrane (B) dispenser (G) is located beneath the cutting edge (1) and the conveyor arrangement (S).
The conveyor or elevator arrangement (S) comprises a conveyor (3) comprising parallel chains (not shown in this drawing), which are linked onto a pair of sprocket arrangements (10). The conveyor (3) also has a plurality of slats (4) laterally displaced relative to the conveyer chains which transfer loosened material (A) from the milled road or pavement surface to a hopper or reservoir (13) which is part of the paver (P) in this example. The slats (4) are bolted to receiving lugs (not shown in this Figure) on drive chains (4) to facilitate feed of the loosened material (A) being processed. The sprockets (10) are keyed to the shaft to ensure alignment and positive drive as the apparatus (R) traverses the site where the pavement is to be laid. Feeder assembly (F) positioned at the front of the apparatus (R) comprises a pair of lateral feed augers (2) which feed loosened material (A) into the slates (4) of the conveyor (3) for transfer to the hopper reservoir (13).
A collecting head (H) comprising a pair of actuatable side arms (shown in Figures 2 and 3) are positioned in front of the feeder assembly (F). The width of the side arm displacement can be adjusted to control the width of the loose material (A) located outside the scope of the cutting edge (1). The operating width of the side arms (shown in Figures 2 and 3) of the collecting head (H) of apparatus (R) is variable through a hydraulically adjustable ram actuator (8), which scoops material (A) towards the feed auger (2) and conveyor arrangement (S). The apparatus (R) comprises tanks (13a) for water or some other additive for treating the loose material (A) before it is fed through the paver (P). Tanks (13a) are located on either side of the hopper (13) in this example. Nozzles (12) are mounted on a spray bar (14) positioned over the hopper reservoir (13) for spraying material (A) with water or some other additive before being deposited in the hopper (13) of the paver (P). The conveyer arrangement (S) and collecting head (H) can be hydraulically raised to facilitate loading a spool (5) of geomaterial onto the dispenser (G). There is typically sufficient space to handle rolls of up to 200m X 4m, which allows an area of 800m² to be treated with a single roll of the membrane.
Figures 2 and 3 illustrate the collecting head (F) of the apparatus (R) of the invention, where the hydraulic ram actuators (8) are visible.
In operation, the apparatus (R) of the invention is mounted onto a paver (P). The paver (P) is driven in the path of loosened road or pavement surface (A). The collecting head (H) of the apparatus (R) is width variable by means of a hydraulically adjustable arms (8) to bring loosened material into the feeder assembly (F). The arm spacing may be adjusted according to the width of pavement (D) being laid. The cutting edge (1) and augers (2) pick up the loose material (A) which is then scooped up into the slats (4) and carried by the conveyer (3) towards the reservoir (13). The material (A) is then sprayed with a mist of water or additive through nozzles (12) mounted on a spraybar (14) before being deposited in the hopper (13) of the paver (P) where it is conveyed to the rear of it and deposited as a new layer of stabilised roadbase (D).
The apparatus (R) will simultaneously deploy a layer of proprietary geotextile material (B) as it traverses the path of the about to paved subbase (D). The spool is unrolled by the forward motion of the apparatus. Since the wheels or tracks of the paver moves forward as the loose material (A) moves through the apparatus (R), an unwind restrictor type tensioner (7) applies a desired tension on the geomterial (B). The treated loose material is deposited on top of the unwound membrane (B) leaving a re-profiled new road base(D) that is strengthened and rejuvenated and protected from water infiltration by the friction surface.

Claims

A process for in situ insertion of a geomaterial underneath a loosened road or pavement surface material comprising the steps of:
(i) lifting at least part of the loosened material to leave at least part of the road base or road subgrade exposed;

(ii) laying a geomaterial onto the exposed road base or road subgrade;

(iii) optionally treating the lifted material with at least additive; and

(iv) relaying the treated material to a predetermined profile on top of the geomaterial,
characterised in that the process is carried out in a single pass by the same apparatus.
The process of claim 1 wherein the loosened road or pavement surface material comprises any uncompacted road base material.
The process of claim 1 or 2 wherein the loosened road or pavement surface material is hot, cold, hydraulically, cement or bitumen bound.
The process according to any preceding claim wherein the geomaterial is are mesh, membrane, textile, grid or fabric membrane.
An apparatus for in situ insertion of a geomaterial underneath a loosened road or pavement surface material, the apparatus comprising a frame, onto which is mounted:
(i) means for lifting loosened material from the road or pavement surface to expose road base or road subgrade surface, said means being provided at the front of the apparatus;

(ii) means for laying a geomaterial onto exposed road base or road subgrade surface;

(iii) means for relaying the material to a predetermined profile on top of the geomaterial,
characterised in the apparatus simultaneously lays the geomaterial onto the exposed road base or road subgrade surface, while relaying the lifted material to a predetermined profile onto the laid geomaterial in a single pass.
The apparatus of claim 5 further comprising means for transferring the lifted material to a reservoir for storing and/or treating the material, the reservoir preferably being a hopper from a paver machine.
The apparatus of claim 6 further comprising means for the spraying of water or additive onto the lifted material, wherein the additive is sprayed onto the lifted material while being transferred or while stored in the reservoir.
The apparatus of any one of claims 5 to 7 further comprising means for transferring the lifted material from the reservoir to the rear of the apparatus so that the lifted material may be relaid on top of the geomaterial.
The apparatus of any one of claims 5 to 8 further comprising means for depositing and/or pre-compacting the material relaid on the geomaterial.
The apparatus of any one of claims 5 to 9 further comprising means for mounting the apparatus onto the front of a paver machine for depositing and compacting the stabilized material on the membrane provided on the exposed road base or road subgrade surface
The apparatus of any one of claims 5 to 10 wherein the means for lifting the loosened material from the road or pavement surface comprises a feeder assembly comprises means for forming a directed flow of lifted loose material.
The apparatus of any one of claims 11 wherein the means for forming a directed flow of lifted loose material comprises horizontally actuatable side blades or arms located on opposite sides of the feeder assembly, and preferably extending forward in front of same.
The apparatus of claim 15 to 18 wherein the feeder assembly further comprises a cutting edge which transfers material to the transferring means.
The apparatus of any one of claims 9 to 19 wherein the means for transferring the loose lifted material to the reservoir is an endless conveyor means, preferably comprising a sprocket and chain conveyor with laterally disposed steel slats to facilitate lifting and transferring the loose material from the cutting edge to the reservoir.
The apparatus of any one of claims 8 to 20 wherein the means for laying a geomaterial onto the exposed road base or road subgrade surface comprises a supply of geomaterial adapted to be delivered onto the surface by forward movement of the apparatus.