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  
       [0001]    The invention relates to a process for rehabilitation or recycling and strengthening of road surfaces using cold recycling technology. More particularly, the invention relates to a process whereby a geomaterial, such as mesh, membrane, textile, grid or fabric membrane, is placed up to 300 mm 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. The invention also relates to an apparatus suitable for retrofitting to existing paver devices for carrying out the process of the invention. 
       DESCRIPTION OF RELATED ART  
       [0002]    Road and pavement surfaces typically comprise structural layers of compacted materials (roadbase) on a compacted subgrade, covered by a friction or surface layer. The friction layer is typically substantially non-structural and is often made up of one or more surface dressing layers which are about 100 mm thickness and which act as water-resistant protective layers with skid resistance. Subgrade, typically formed of non-bound material, is the in-situ native material upon which the road or pavement structure is placed or constructed at selected location. 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 constitute asphalt 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, 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. 
         [0003]    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. 
         [0004]    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. 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. 
         [0005]    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. 
         [0006]    Surface rehabilitation tackles defects in the upper parts of the road, at a thickness of about 50 mm to 100 mm, whereas structural distress requires recycling or rehabilitation to depths of over 200 mm, even to 300 mm on occasion. Asphalt overlay is the simplest repair process and involves paving a thin 40-50 mm hot mix asphalt overlay onto an existing surface. Damaged layers of asphalt can be milled off and replaced with fresh course while maintaining the supporting layers. Recycling a thin layer of about 50-150 mm of the asphalt layer can be done by hot in-situ processes, whereas deeper conditioning requires cold in-situ or in-plant recycling processes which can tackle rehabilitation at depths of up to 300 mm. Hot paving is useful where the damage is only to the road surface or dressing layers, for example, poor grip or minor surface damage to about 50 mm depth. Hot paving can be carried out by machines such as those described in U.S. Pat. No. 4,011,023, which discloses an asphalt pavement recycling apparatus. This is a machine for hot recycling of a macadam highway pavement, whereby a pickup device removes crumbled pavement material from a roadbed sit, and heaters heat the material as it passes through the machine. Typically the hot recycling process starts with a heating and milling pass to heat and scarify the macadam to be recycled. The relatively soft, hot, lubricated material is easily picked up by a lifting means comprises a chain conveyor having flights which carry the material to heaters within the machine. An applicator applies liquid asphalt to the material to form a rejuvenated mix. Simultaneously, roadbed heaters heat the roadbed site, and an applicator applies liquid asphalt. A spreader spreads the mix on the roadbed site, and adjustable screeds preliminarily form the spread mix for final working into a finished road. Such systems are not suitable for lifting roads milled to greater depths, for example, 100-300 mm, as are used in cold road recycling. Such milled roadbeds are typically full of hard rock and lumps and cannot be easily lifted by existing reprofiling devices. Cold milling machines are first used to mill a thin layer of the surface. Such processed surfaces are ideal for deposition of a thin layer of fresh hot asphalt dressing using a standard road paver. Tack coats of modified butument emulsions may be applied under the dressing to seal the surface and facilitate bonding of the asphalt surface dressing. Such methods are extrement efficient from the time, environment and econonical standpoint. 
         [0007]    Even more economical and environmentally friendly are cold paving techniques which can also be used in place of full road replacement. After the cold thin layer milling step which mills the road surface up to 50 mm, the road surface is levelled, and treated paving mixture is applied. The levelled surface and new dressings bond to form a new surface. The cold paving mix is distributed across the full width in two separate layers, the first being the profile, the second the surface course layer. 
         [0008]    Hot recycling can be used where wear and tear results in porous, crack or other deformations in the road surface. The process involved heating the existing surface to soften it so that recycler machines can remove the lubricated surface course, mix it with any necessary virgin mix and relaying it using standard asphalt pavers. 
         [0009]    Asphalt pavers are quite commonplace and all share a common configuration having a hopper for hot macadam (HMA) in the front, a material feed system for carrying HMA to the rear of the machine by a set of flight conveyor belts, augers for spread out laid material, and a screed for leveling and compacting the surface. Paving machines also have a push roller and truck hitch arrangement which is located on the front of the hopper. The push roller is the portion of the paver that contacts and pushes against trucks that deliver the HMA material to the hopper. The truck hitch holds the transport vehicle in contact with the paver. Trucks reverse to the paver and deposit HMA into the hopper. The material feed system conveys the HMA from the hopper, under the chassis and engine, then to the augers. The amount of HMA carried back by the conveyors is regulated by either variable speed conveyors and augers or flow gates, which can be raised or lowered by the operator or, more often, by an automatic feed control system. The auger receives HMA from the conveyor and spreads it out evenly over the width to be paved. Operation of the material feed system, can have significant effects on overall construction quality and thus long-term pavement performance. HMA must be delivered to maintain a relatively constant delivery of material in front of the screed. This involves maintaining a minimum amount of HMA in the hopper, regulating HMA feed rate by controlling conveyor/auger speed and flow gate openings (if present), and maintaining a constant paving speed. A fluctuating HMA head in front of the screed will affect the screed angle of attack and produce bumps and waves in the finished surface. Furthermore, the hopper should never be allowed to empty during paving as this can results in the leftover cold, large aggregate in the hopper sliding onto the conveyor in a concentrated mass and then being placed on the mat without mixing with any hot or fine aggregate. 
         [0010]    Where damage extends into the subgrade, a more serious repair must be undertaken to restore strength and stability. Typically, the road is processed using cold milling techniques, whereby the damaged road layers are milled to depths of up to 300 mm, far greater that those used in hot paving techniques involving surface dressing only. In this fashion surface course, binder and even part of the base layer are milled up together. Binder agents are added in precise amounts depending on measured requirements. All of the worn road material is recycled by adding one or several binding agents. Existing methods and apparatus for carrying out cold regeneration 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. The cold process can be carried out in situ, or in-plant. In situ involves the use of a expensive cold recycling trains, and the treated material is laid on site. Using the in-plant process requires that material is recycled off site to a treatment plant and returned by truck for relaying after treatment. A thin surface course of virgin asphalt mix can be applied on top of the cold recycled layer by standard road pavers, and is then compacted by rollers. The in situ process is extremely efficient, however, many roads are inherently unsuitable for in-situ cold recycling using sizeable cold recycling trains, for example, where serve damage to the subgrade has occurred, poor access, smaller country roads, or heavy traffic flow. In such cases, typically in-plant methods are used as they are less costly than maintaining cold recycling trains. The drawback of the in-plant method mainly arise from a large increase in cost and jobtime as materials have to be hauled from site to the treatment plant and back, rather than utilising the one pass methods facilitated by cold recycling trains. It is therefore one object of the present invention to faciliate alternative means for cold in situ recycling. 
         [0011]    As discussed above, hot mix road recycling trains for recycling asphalt and wearing course bituminous macadam have been available for quite some time, but are large and expensive machines and 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 and so simply hot thin dressing replacement is usually not possible or troublesome. Such roads are typically maintained by repeated rounds of surface dressing replacement of the friction course using asphalt pavers and by occasional deepening and strengthening of sections 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. As 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 applied using simple paving devices, 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 and regularly implemented. In reality, cold recycling or complete rehabilitation is the best method to re-strengthen and stabilise such roads. However, for the reasons described above, cold in-situ recycling or indeed cold in-plant recycling may be extremely costly, where appropriate at all. It is one object of the present invention therefore, to provide improved process and an apparatus for cold in-situ recycling of such roads. Cold recycling involves recovering and re-using 100% material from an existing pavement, without the addition of heat. Whereas hot recycling is restricted to heating and reusing upper layers of asphalt material on roads, cold recycling can be applied to both thin layers of asphalt (typically to 50 mm depth) to thicker layers (to about 300 mm) that include more than one different pavement materials (full depth reclamation). One advantage resulting from the cold reclamation being that a single thicker layer of stabilised material is far stronger than separate thin layers making up an equivalent thickness. Furthermore, cold recycling machines are designed to recycle thick paving layers in a single pass. As such, modern recycling machines are usually huge, powerful machines, often set on tracks, and which can have inbuilt milling capacity, pumping systems for addition of binders and other fluids, storage tanks for such chemicals, and paving screens for reprofiling the recycled materials. As mentioned above, the size and oftentimes cost of these powerful machines is prohibitive for their use on small or unstable regional or country roads or paths. 
         [0012]    Accordingly, it is an object of the present invention to provide an alternative, more economical and accessible means for facilitating cold recycling on small or unstable regional or country roads or paths, or the like It is a further object of the present invention to provide means for cold recycling without requiring need for purchase or hire of large and expensive cold recycling machines. Geomaterials are commonly used in road construction for the retardation or prevention of water movement for example vertical movement. Suitably then they comprise 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. If a geomaterial is required, it can only be laid after the road-lifting step has exposed the road base or subgrade. 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. 
         [0013]    EP 0 241 803 describes laying down the grid fabric on a road level of a bituminous carrier (asphalt) layer, the layer having been prepared in a pre-fabric laying step. The fabric web is wound onto a carrier sleeve aligned transversely to the direction of fabrication is fixed against the road level and the fabric web is wound off the support sleeve in the direction of fabrication by moving the support sleeve and the mixed product for forming the pavement is applied to the laid-down grid fabric by means of a pavement fabricator, the pavement fabricator equipped with a screed having a beam distributing and releasing the mixed product over the fabrication width in the direction of fabrication behind the screed and having in front of the running gear pushing rollers for the lorries bringing the mixed product to the pavement fabricator. To enable the fabric web to be laid down correctly and without folds and to fix the laid-down web as quickly as possible, the fabric web is wound off a carrier sleeve located between the push rollers and the beam of the pavement fabricator during the fabrication of the pavement and the carrier sleeve is moved together with the pavement fabricator in the direction of fabrication. This device appears to be part of a surface dressing process, where a milling machine has milled and lifted an asphalt surface to a desired depth, and the lifted material is delivered by truck to paver reservoir located on the front of the paver, whereby it is conveyed to the paver screen and overlaid on the deposited fabric. The system is said to be useable with a repaver device; however, neither devices would suitable for cold carrying out recycling process at cold rehabilitation depths. Prior art repavers are only capable of lifting from X to Y mm of milled and/or heated lubricated surface dressing layers, Thus, it is a further object of the present invention 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  
       [0014]    According to the present invention, as set out in the appended claims, there is provided an in situ recycling 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,       
 
         [0019]    characterised in that the process is carried out in-situ in a single pass by the same apparatus. 
         [0020]    Preferably, the process is preceded by the step of adapting an existing paver to operate as an in-situ recycling machine by mounting the apparatus of the invention described below onto the paver. 
         [0021]    Thus in a preferred embodiment, there is provided an in situ recycling process for in situ insertion of a geomaterial underneath a loosened road or pavement surface material comprising the steps of:
       (i) adapting a paver to operate as an in-situ recycling machine by mounting an apparatus as defined herein onto the paver;   (ii) lifting at least part of the loosened material with the adapted paver to leave at least part of the road base or road subgrade exposed, wherein loosened material has a depth of from about 1 to 300 mm;   (iii) laying a geomaterial onto the exposed road base or road subgrade;   (iv) optionally treating the lifted material with at least additive; and   (v) relaying the treated material to a predetermined profile on top of the geomaterial,       
 
         [0027]    characterised in that the process is carried out in-situ in a single pass by the adapted paver. 
         [0028]    This facilitates lifting at least part of the loosened material with the adapted paver to leave at least part of the road base or road subgrade exposed, wherein loosened material has a depth of from about 1 mm to about 300 mm. Suitably, the loosened material is at a depth of from about 25 mm to about 200 mm. More suitably still, the loosened material is at a depth of from about 100 mm to about 150 mm. 
         [0029]    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. Preferably, the material is cold and the process concerns a cold recycling road rehabilitation process. The present invention thus allows for lifting of the in-situ road materials at a depth of from X to Y, 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 extremely efficient process that allows for geomaterial installation up from about 1 mm to 300 mm beneath a road surface. Suitably, the material can be laid at a depth of from about 25 mm to about 200 mm. More suitably still, t a depth of from about 100 mm to about 150 mm. 
         [0030]    In a preferred embodiment, the lifted loose road or pavement surface material may be treated with at least one additive, selected to enhance particular mix attributes, for example, a binder, to a pre-selected dosage using a calibrated or metered dosing arrangement. 
         [0031]    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 materials from 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. 
         [0032]    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. 
         [0033]    Thus, the invention concerns a highly efficient process for road rehabilitation, particularly, cold rehabilitation of road surfaces to a depth of from 1 to 300 mm, etc. as described above, and more particularly where insertion of a geomaterial is desired at these depths. 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, redepositing the lifted or site won material to form a new rehabilitated and rejuvenated road surface. In a preferred embodiment, the process involves 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. 
         [0034]    The process is advantageous over prior art method of geomaterial placement in that deeper depths can be achieve for laying the geomaterial. 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. 
         [0035]    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 about 1 to about 300 mm, more preferably from about 60 to about 200 mm, more preferably still from about 80 to about 150 mm. 
         [0036]    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 then be topped with a friction course, typically comprising a suitable surface dressing, such as a bituminous sealing layer, for example. 
         [0037]    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 rehabilitation and strengthening process to be carried out in the cold, in-situ, in a single pass fashion, whereby recycling occurs to a depth of from 50 mm to about 300 mm of milled or loosened road material. Advantageously, the apparatus of the invention may be used to retrofit a regular asphalt paver to convert the paver to a cold in-situ recycling device, capable of lifting recycled material from a depth of about 50 mm to about 300 mm. The apparatus of the invention is extremely useful as it obviates the need for purchase or hire of expensive cold recycling machinery. Since the apparatus can be fitted to existing pavers, the apparatus of the invention is significantly smaller in size than existing cold recycling machinery. Using the apparatus of the invention with a standard asphalt paver means previously inaccessible smaller or rural roads may be subjected to cold in-situ rehabilitation methods. Advantageously, the apparatus of the invention may be easily added into existing in-situ recycling processes or machinery or can be used to replace relevant part of such 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. 
         [0038]    Accordingly, in a first aspect of the invention, there is provided an apparatus for converting a paver to an in-situ road-recycling device, the apparatus having a frame mountable onto the front of the paver, comprising: 
         [0039]    (i) means for lifting and delivering loosened material from a road or a pavement surface to a reservoir on the paver device to expose road base or road subgrade surface; 
         [0040]    (ii) optional means for treating the loosened material with at least one fluid and/or at least one stabilizing additive; 
         [0041]    (iii) optional means for laying a geomaterial onto exposed road base or road subgrade surface; 
         [0042]    wherein the material is re-laid onto the road base or the road subgrade by the paver in a predetermined profile in a single pass. 
         [0043]    Desirably, the apparatus of the invention converts a standard paving device, such as an asphalt paver device, into an adapted paving device (functioning as a cold in-situ recycling machine) which is suitable for use in a cold recycling process, where loosened road material, up to a depth of 300 mm, may be lifted, optionally treated or stabilized, and re-laid by a standard paver having a screed arrangement. 
         [0044]    Preferably, the apparatus of the invention is mounted onto the paver in such a way as to ensure that the frame of the apparatus is height adjustable. In other words, mounting means is provided on the frame such that the frame and particularly the means for lifting and delivering loosened material from the road or the pavement surface to the reservoir may be raised and lowered as desired to reach a predetermined lift depth of loosened material. Preferably, the frame may be mounted onto the front of the paver by at least one mounting arms. Preferably said arms are pivotally mounted onto the paver, for vertical upwards and downward movement thereon. Hydraulic cylinders may be provided proximate to the arms, so that the apparatus may be lifted and lowered as necessary, for example, for selecting am operating depth of lifting material up to about 300 mm, for raising the apparatus for maintenance, transport or for replacing the geo-membrane roll as necessary. 
         [0045]    In a preferred embodiment, at least one height adjustable wheel is provided on the frame to assist further height/lift depth adjustment of the apparatus of the invention. Preferably, the at least one wheel may be mounted behind a pick up head provided on the frame. The height adjustable wheel may be hydraulically operated. Preferably, electrical and hydraulic power is supplied to the apparatus of the invention by connection to the pavers systems. Tension may be applied to the geotextile roll/spool by extending a pivoting tensioner from the frame of the apparatus. Tension may be applied to the spool of geotextile as it pivots from the frame of the machine. 
         [0046]    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: 
         [0047]    (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; 
         [0048]    (ii) means for laying a geomaterial onto exposed road base or road subgrade surface; 
         [0049]    (iii) means for relaying the material to a predetermined profile on top of the geomaterial, 
         [0050]    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. In this embodiment wherein the means for laying a geomaterial is present, the apparatus of the invention, when mounted onto a paver, may simultaneously lay the geomaterial onto the exposed road base or road subgrade surface (at the desired predetermined depth), while relaying the recycled (lifted) material to a predetermined profile onto the laid geomaterial in a single pass. In other words, in this embodiment, in operation, the apparatus facilitates the in situ insertion of a geomaterial underneath a loosened road or pavement surface material in a single pass operation using standard asphalt paver technology. The geomaterial may be laid under, up to about 300 mm depth under the surface. Existing prior art pavers having geomembrane dispensing means are not suitable for laying membrane to this depth. The apparatus of the invention therefore facilitates depositing and compacting the recycled road material onto a membrane provided on the exposed road base or road subgrade surface. Preferably, the geotextile roll is mounted onto a horizontal axis on the frame, may be extended, for example, telescopically extended so that wider rolls of geotexile may be accommodated and laid, depending on the requirements of a particular application. Prior art dispenser described in EP 0 241 803 is part of a machine having push rollers for use with material delivery trucks. The skilled person would appreciate that the maximum width of these machines is therefore about 2.5 m. Accordingly, this would be the maximum width of geomaterial that could be used with this prior art machine. The present apparatus can facilitate delivery of up to 4 m of geomembrane through use of telescopically extendible horizontal axis for supporting a wider geomembrane roll. 
         [0051]    Preferably, the apparatus of the invention comprises means for delivering or transferring the lifted material to a reservoir means on the paver for storing and/or treating the material. The reservoir is for holding the lifted loosened material and any necessary additives that may have been incorporated into the material in the reservoir so that it may be consistently laid by the paver in it&#39;s normal mode of operation. In a preferred embodiment, the reservoir for the lifted loose material is a hopper or a modified hopper of a paver machine. In other words, in this embodiment, the apparatus connects to the front of an existing asphalt paver and integrates completely with same. This retrofitting converts a standard paver into a cold in-situ recycling device. The apparatus is mountable, through provision of means for mounting the apparatus onto the front of a paver machine. Suitable means include extending side arms for example, and may include use of brackets, hook or other connecting arrangements known to the person skilled in the art. Preferably, the mounting means allows the arms to pivot about their connection to the paver to allow vertical movement thereon for height adjustment of the device. Advantageously, the apparatus may then utilise the hydraulic, mechanical and electrical outputs of the paver. In a related aspect the apparatus can be supplied and used as a component in a new type of machine suitable for carrying out all aspects of the inventive process described above. 
         [0052]    Suitably, the apparatus of the invention may further comprises means for adding water or at least one other additive or fluid onto the lifted (recycled) material and/or the reservoir of the paver. 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. The spray bar may have a plurality of nozzles for even distribution of additive. 
         [0053]    The standard paver, to which the apparatus is attached, typically comprises means for transferring the lifted material from the reservoir/hopper to the rear of the paver so that the lifted material may be re-laid on top of the geomaterial. For example, a conveyor may be used to transferring the lifted (recycled) material from the reservoir to the rear of the paver so that the material may be re-laid on top of exposed surface or the geomaterial where used. In a preferred embodiment, the paver further comprises means for depositing and/or lightly pre-compacting the material re-laid on the geomaterial provided on the exposed surface. Suitably, means for depositing and/or pre-compacting the material re-laid on the geomaterial is also included, for example, a paver screed. 
         [0054]    In a preferred embodiment of the apparatus of the invention, the means for lifting the loosened material from the road or pavement surface comprises a feeder assembly. The feeder assembly suitably comprises means for forming a directed flow of lifted loose material. Suitably, the feeder assembly is mounted onto the front of the apparatus in the form of a pick up head. The feeder assembly may also comprise a cutting edge that ensures a clean edge is taken from the material in the path of the machine to facilitate efficient transfers of material to the transferring means. The feeder assembly may further comprise a cutting edge which transfers material to the transferring means. The pick up head may comprise a frame encasing a series of horizontal shafts which in turn drive the conveyor through a chain and sprocket system powered by an hydraulic motor fed by the paver itself. In a preferred embodiment, the blades, arms or wings may be provided with a vertically mounted baffle forward of the mouth of the feeder assembly to ensure an even feed of material, and to prevent crowning. At least one auger may be provided about the working width of the lifting means. Preferably, a pair of augers is provided. Suitably, the augers may be short flight augers. 
         [0055]    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. The conveyer may be provided with laterally disposed slats and/or rakes to facilitate lifting and transferring the loosened material onto to conveyer and into the reservoir/hopper of the paver device. Suitably, the slats and/or rakes are of steel or other suitably hard and wear resistant material. In a preferred embodiment, an arrangement of alternating slates and rake is provided. Use of a combination of slats and rake is preferred, rather than slats alone as found in prior art conveyors, as this arrangement facilitates efficient pick up of the loosened material from the ground. The skilled person will appreciate that cold recycling involves cold, rocky, uneven, hard and bulky material and so it not as easy to pick up as hot or melted milled macadam, which is loose, lubricated and sticky. When only slats are used, if the loosened material is rocky or clumpy, the slats alone tend to bang off the material rather than picking up same. The slate and rake arrangement has been found to facilitate actual lifting of the cold loosed material in these cases. Suitably, the slates and/or rakes may be interchangeably positioned on the conveyor as necessary. Clockwise motion of the belt and consequently, the slats and rakes, allow the slates and rakes at the cutting edge to engage well with the loose material being collected to lift it onto the conveyor for transportation into the paver reservoir or hopper. In a preferred embodiment, the conveyor means, is a endless conveyor belt type arrangement having a first and second pulley (the first of which is a lead pulley for revolving the conveyor), having a third idler pulley located in a vertically disposed position (or otherwise located clear of incoming material) above the second pulley. The idler is positioned such that the slats on the belt may present themselves at right angles to the ground before becoming engaged with the material to be lifted. This idler pulley arrangement has been found to facilitate the lifting action and minimising the tendency of the slats to bang off the material, rather than engaging with same in a lifting action. Prior art conveyors in pavers, or repavers do not have this three pulley arrangement. 
         [0056]    More preferably still, the apparatus of the invention further comprises means for directing the loosened material into the cutting edge area for pick up. Suitably, the means for directing the flow of loosed material comprises horizontally actuatable side blades, arms or wings located on opposite sides of the feeder assembly. Desirably, the blades, arms or wings are provided in a pair, one of each on opposite side of the feeder assembly. Preferably, said side blades, arms or wings extend forward in front of the feeder assembly. The hydraulically actuatable blades, arms or wings may be hydraulically adjusted vertically and horizontally. The blades, arms or wings are suitable for adjusting the width of the directed flow to a predetermined width. This facilitates feeding material which is outside the scope of the lifting means into the correct position for optimised uptake and lifting by the cutting edge. The blades, arms or wings are horizontally actuatable so that width of material entering the device may be controlled, whereas the vertical movement allows the blades, arms or wings to follow the contours of the ground as necessary, where terrain is uneven. 
         [0057]    In a preferred embodiment, a blade may be mounted at the bottom of the feeder/lifting means. Preferably the blade is mounted horizontally at this location. The blade forms a barrier between the remaining road surface and the material which is being removed by the machine, ensuring a clean surface is left behind for relaying. 
         [0058]    In a preferred embodiment, the apparatus further comprises calibration or metering means for measuring the amount of lifted material to be treated with additives. Preferably, said calibration or metering means is provided on the transferring means, for example, the conveyor system. 
         [0059]    As described in a preferred embodiment, the apparatus of the invention may further comprises means for laying a supply of geomaterial onto exposed roadbase, subgrade or other surface, said means 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 frame of the apparatus, for example, rearward of the height adjustable wheels where provided Desirably, the supply is provided on the underside of the apparatus. Suitably, dispensing of geomaterial 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, thereby avoiding kinks or creases in the laid membrane. 
         [0060]    In a preferred embodiment, the apparatus of the invention comprises means for adding water or other additive (for example, binder) to the lifted material. Preferably, additive is added while the material is on the transferring means (for example, the conveyor). Desirably, said means comprises a spray bar provided above the conveyor or at the top of the conveyor. A plurality of nozzles may be provided on the spray bar to facilitate even addition. 
         [0061]    In a preferred embodiment, the apparatus of the invention further comprises storage means for holding the water and/or additives until required for use. Suitable storage means include at least one tank, reservoir or the like, provided on the apparatus or otherwise connected to the apparatus. Preferably a pair of tanks may be provided on either side of the reservoirs of the paver. 
         [0062]    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. 
         [0063]    In a related aspect, there is provided a method of retrofitting a paver comprising mounting the apparatus of the invention onto the front of the existing paving device. Suitably, the apparatus of the invention is electrically and hydraulically connected to the paver. 
         [0064]    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. 
         [0065]    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  
         [0066]    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: 
           [0067]      FIG. 1  illustrates a schematic sectional drawing of an apparatus of the invention mounted onto the front end of a paver machine in use; 
           [0068]      FIGS. 2 &amp; 3  illustrate top perspective photograph views of the front of a prototype of the apparatus of the invention; 
           [0069]      FIG. 4  illustrates a top perspective photograph view of one side of a prototype of the apparatus of the invention; 
           [0070]      FIG. 5  illustrates a perspective photograph view of the top of a prototype of the apparatus of the invention; 
           [0071]      FIG. 6  illustrates a side view of a further embodiment of the apparatus of the invention mounted onto the front end of a paver machine; 
           [0072]      FIG. 7  illustrates a cross sectional view from the side of the further embodiment of the apparatus of the invention shown in  FIG. 6 ; 
           [0073]      FIG. 8  illustrates a top plan view of the apparatus of the invention in the unmounted state; 
           [0074]      FIG. 9  illustrates a top perspective view of the apparatus of the invention in the unmounted state. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0075]    Referring now to the drawings and specifically  FIGS. 1 to 9  inclusive and initially  FIG. 1 .  FIG. 1  shows an apparatus of the invention generally by reference (R) pivotally mounted on to the front end of a paver machine at connector ( 14 ), hereinafter called a paver (P) via a pair of mounting arms ( 11 ). The paver (P) ideally is 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), 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 behind the cutting edge ( 1 ) and underneath the conveyor arrangement (S), where it is held onto frame (M) with bolts ( 7 ) and ( 8 ). 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 ( 10   a ) (not shown in this drawing), which are linked onto a pair of sprocket/pulley arrangements ( 10   b,    10   c ). 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 to facilitate feed of the loosened material (A) being processed. The sprockets ( 10 ) are keyed to the frame/shaft (M) to ensure alignment and positive drive as the apparatus (R) traverses the site where the pavement is to be laid. Feeder assembly (F) (not shown in this drawing) 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 ). The collecting head (H) comprising a pair of actuatable side arms (shown in  FIGS. 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  FIGS. 2 and 3 ) of the collecting head (H) of apparatus (R) is variable through a hydraulically adjustable ram actuator (not shown), which scoops material (A) towards the feed auger ( 2 ) and conveyor arrangement (S). The apparatus (R) comprises tanks ( 13 ) for water or some other additive for treating the loose material (A) before it is fed through the paver (P). Tanks ( 13 ) are located on either side of the hopper ( 13 ) in this example. Nozzles ( 12 ) are mounted on a spray bar ( 12   a ) 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 200 m×4 m, which allows an area of 800 m 2  to be treated with a single roll of the membrane.  FIGS. 2 and 3  illustrate the side arms ( 5   a,    5   b ) of the collecting head (H) of the apparatus (R) of the invention, where the hydraulic ram actuators ( 8   a,    8   b ) are visible for telescopic extension of the axis for holding the membrane spool, as are hydraulic ram actuators ( 6   a,    6   b ) for moving the side arms ( 5   a,    5   b ). 
         [0076]      FIGS. 4 and 5  illustrate the apparatus of the invention from the side and from the top.  FIGS. 6 and 7  illustrates a side view of a preferred embodiment of the invention, wherein the apparatus (R) is attached to an existing road paver (P) via a pair of mounting arms ( 11 ) which are vertically moveable by action of hydraulic cylinder ( 11   a ) which control the operating position of the machine as well as its transport position. Power is provided to its hydraulic motor ( 11   b ) from the paving machine (P). Further height control of the apparatus (R) is achieved by the height control wheels ( 15 ), which are mounted directly behind the collecting head (H). Collecting head (H) comprises of al frame (M) encasing a series of horizontal shafts which in turn drive the conveyor arrangement (S) through a chain ( 10   a ) and sprocket/pulley system ( 10   b,    10   c,    10   d ), comprising drive pulley or sprocket ( 10   b ) connected to hydraulic motor, working pulley or sprocket ( 10   c ) and idler pulley or sprocket ( 10   d ), which are powered by an hydraulic motor ( 11   b ) fed by the paving unit (P) itself. A screw adjustment on the shaft carrying the driving sprocket puts tension on the chain drive system. Interchangeable slats ( 4 ) and rakes ( 4   a ) are affixed to chain, transversely. These engage with the loose material (A) being collected and move it into the hopper ( 13 ) of the paver (P). Forward of the collecting head (H) are mounted two extension wings ( 6   a,    6   b ) which are moveable horizontally and vertically by means of hydraulic actuators ( 6   c ) controlled by the operator of the paver (P). The horizontal movement controls the width of material taken in by the machine and the vertical movement allows the extension wings to follow the contours of the ground. Cutting edge ( 1 ) ensures that a clean edge is taken from the loosened material (A) in the path of the machine. A horizontal blade ( 17 ) is mounted at the bottom of the feed chute. This forms a barrier between the remaining road surface and the material (A) which is being removed by the machine. Baffles ( 16 ) provided on side arms are also shown, as are the hydraulic actuators ( 5   c,    5   d ) for operating same. 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 be 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 geomaterial (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. In operation as the machine traverses the loosened material (A), the material (A) is gathered into a wind-row by the collecting head (H) and fed into the mouth of the conveyor by the cutting edge ( 1 ). Vertically mounted baffles ( 16 ) forward of the cutting edge ( 1 ) of the machine ensure an even feed of material, and prevent crowning. Material (A) is gathered towards the working width of the conveyor by two horizontally opposed short flight augers ( 2 ). It is then moved up along the floor of the feed chute by interchangeable slats ( 4 ) and rakes ( 4   a ) mounted on conveyor chains ( 10   a ). The leading idler pulleys ( 10   b ) on this chain drive system are vertically disposed above, and clear of incoming material (A) so as to allow the interchangeable slats ( 4 ) and rakes ( 4   b ) to present themselves at a right angle to the ground before becoming engaged with the material (A). The material (A) is sprayed with a mist of additive through nozzles ( 12 ) mounted on a spray-bar ( 14 ) before being deposited in the hopper ( 13 ) where it is conveyed to the rear of the paving machine (P) and deposited as a new layer of road surface (D). The machine is designed to deploy a geotextile grid (G) for geo-stabilisation operations using its geotextile grid dispenser (G). This is mounted rearwards of the height control wheels ( 15 ) and is extendable to cater for the different widths of geo-textile grid available and to suit varying paving applications. Tension is applied to the geo-textile spool ( 5 ) as it deploys it in the path of the machine by a tensioner ( 7 ) which pivots from the frame of the machine. The device has an inherent system, where the collected material is treated with an additive, stored in proprietary tanks ( 13   a ) on either side of the hopper ( 13 ) before it is fed through the paver (P).