GB2528905A - Asphalt road repair - Google Patents

Abstract

The apparatus comprises: a heater array, 1, 2, 3, 4; a mixer 26 and a screed 22. The heater, mixer and screed are arranged linearly from front to back onto a single movable machine, the front being the motion of the machine moving forwardly F. The heater is for heating asphalt wearing courses on both sides of a joint. The mixer can deposit heated bitumen and has agitators for disturbing the heated asphalt and then mixing the asphalt, bitumen to create a mixture and aggregate. The screed spreads and tamps the mixture on the road surface. Also claimed is a method including the successive steps of: a) heating a surface of asphalt wearing courses; b) spraying heated bitumen onto the surface; c) agitating the asphalt and partially mixing the bitumen; d) adding aggregate onto the disturbed asphalt and bitumen; e) agitating teh asphalt, bitumen and aggregate and mixing them together and f) spreading the tamping the mixture on either side of the surface of the joint.

Description

Asphalt Road Repair

FIELD OF THE INVENTION

The present iiwention relates to methods and apparatus for repairing asphalt roads, DarUcula.rIy but riot exclusively to repairing longitudinal joins between adj:acert wearing courses.

BACKC ROUND ART

An asphalt road is constructed in layers for optim**urn load distribution, an.d allows the stresses and strains from the véhides passing over head to be transmitted: through the road structure, which then spread. and lessen with depth, In order to achieve this. sb'onger and consequently more expensive materials are used ir the upper evels, with relatEvely low st-ergth materials oeig used n the lowe layers It s aso important that a good bond is achieved between all of the layers to ensure the road structure acts as a single structural ent>tv with good bearLng capacity The wearing course, or too layer of a ad rna consist of up to three asphalt layers. a surface course, a binder course and an asphalt base course -and together these constitute the top layer of the road structure ard overile a structural road base layer (which usuafly also comprises several layers).

There are a wide rançe of surmce course pecictions, and these wearing mixtures must be designed to have sufficient stability and durability to withstand the aDpropdate 25. traffic loads and the detrimental effects of environmentailvinduced stresses -such as air.

water and temperature changes -without exhibiting cracking, rutting or other failure modes.

Their usage aso depends on spedflc requirements, local conditions anti functional characteristics, such as traffic levels, skid resistance, ncise reduction and durabiii in some casec, rapd drainage of surface vater is desirea, whe in other cases the weanng course shculd be impermeable, to. keep water out of the road stn4cture.

The binder course is an:intermedate ayer. It is designed to reduce rutting and S withstand the highest stresses that occur about 50-70 mm below the surface course layer.

Binder mixtures typicay use a large aggregate size (19-38 mm) with.a corresponding lower asphalt bihder content to produce a combination of stability and durability.

The asph&t base course mixtures hate a maxurum aggregate size (up to 75 flT and an even lower asphalt binder content, providing adequate durablity since th:i' layer is JO not exposed to the environment.

In sme roads th three asphalt courses may only comprise two layers, cr even one; n the first case, the uppermost layer is referred to hereinafter as the surface course a'd the two layers together are the weari.n course, in the second case there is only the surface course which conStitutes the, wearino course.

Many -oads are provided with several carnageways, or traffic lanes, each aboet 3-4m in width. In conStructing such roads, the structur[ road base layer is often made in' a single width extending over the entire width of the road. However, the wearing courses f these roads are often constructed to the width of the carriageway only or traffic lan.e by a paver (also known as a paver finisher, asphait finisher or pavng machine) Tke paver has an auger which places a stockpile of heated asphalt (a mixture of bitumen and aggregate) onto the road nase layer n front of a screed which spreads the matenal over the width of the carriageway and provides initial compaction to leave a relatively sopth,, unifcrrn surface; The wearing course is then My con pactS by a road roller.

Where adjacent wearing courses abut there is a longitudinal joint which extends between them running in the direction of the road; this joint may be Sealed with a strip of Diturnefl, ruboer or similar compound It also often aelineates the Douncarv betwe ad jacen:t traffic lanes, and, so reflectors known as cats eyeC may be. inserted into the waarIhg surface along this line, and it may also be pattially covered by lane markings. Tnese longitudinal joints are susceptible to fail well before the remainder of' the wearing course for a vanetv of reasons such as the ingress of water and the action of ftost, poori formed or cut joints, insufficient compaction of the wearing courses at their edges, poor matching of aspnaft niatenals in adjacent weanng courses, raccurate supp of marerals vhen constructing the wearing courses and so on, Failure at. these joints is often. seen as cracks, widening and/or deepening to potholes to the depth of the wearing course along the line of S the longitudinal joint, whilst the remainder of the wearing course, away from the.

lcgitud.inai joint (more than about. O.3m transversely -any wider failure is. usuauy a major fault which must be repaimd immediately befcre the road and/or traffic is. damaged severely) is stiil intact and has. many years of useful life remainIng. The extent.. of longitudinal joint failure normally varies along the length of the joint some lengths of the IC joint may be severely damaged, Whereas other extents, of the joint y only slightly damageci, or even in oqd repair.

The repair of failed longitudinal joints is. often carried out piecemeal, where the fa lure s part cula-ly deep or wide aid leaves a sgnifIcant area of struct.jral -ocri base laye-epen to weathering and damage by passing traffic.. This is partly because. the varying extent of failure aiorig the joint makes it quicker and eaSier to tarrj out patch repairs, which are usualy made us.ng only smaller hand-operated mach nery anc with a large dnount of manual input. Alternatively, repairs are carried out using, similar machinery as was used U the initial constructic.n of a. wearing course, and over a width about the same as the original wearing: course: firstly the surface is. prepared for repair using a "cold planning" process, in which a rotating cylindrical roller With protrusions removes the wearing course. The roller 5: about. the same width' as the carriageway, and is rotated with such: power that the wearing surface s broken up (wth the aggregate itsef beng smashed, or pulvensed) and renovec (I. cannot be re-used as the aggregate has been smashed and will no longer be of' the: speci4ied sze for the weang course), 1eavmg a structural roac base layer the uoper surface c,f which is scored by the protrusions -the score Unes provide a "key" for the new wearing course to attath to -as the cold plannng machule s drven along the road There to'lows a paver which lays an entirely new wearing course as in the initial construction process, followed:by a road roller. It will be appreciated that the former prccess is slow, and requires dat the. road be blocked either side of the part of the jolnt under repair, or the provision of twnporary traffic controls to divert traffic onto a carriageway removed from the repair. The second process' is also relatively slow, because the width of wearing course under recair is extensive and, as the dfferent machines need room to manoeuvre and to be separately con.troiled and directed.manualtc this process' also means that whilst the repair work' is taking place a. significant. part of the road is blocked. The patch repair method is particurarly uniike.i' to match the material of the repair with that of the originai wearir..g course, resultIng in a repair which is almost as vulnerable to iiure around its: edges as the original longitudinal joint (and therefore has a life which is different twin that of the wearing course),. ahd which either stands proud of the oiginai wearing surface or which. is soon compacted into a shallow depression -each of which cause discomfort when driven over.

The cardaçevay wdt.h re ai.r method is less likely to resvlt. in a wearing urfCe which stands proud of, or below, the surrounding wearing course, however it effectivei creates two new ongtuthn& ;ornts along either sae of the repair, arid these jo nts are as susceptible to failure for the same reasons as was the origjna.i joint.

SUMMARY OF ThE INVENTION

The present invention provides apparatus for repairing, a longitudinal joint beeen adjonng asphalt road wearing courses, the apparatus compnsng a heater array or heating. the surface of the asphalt wearing courses on both sides of the joint; a mixer for depositing bitumen and heated aggregate onto the heated surftces, h.avina agitators for metharicaily disturbing the heated asphalt over.a predeterrr.ined distance which extends transversely over the joint and to either side of it, and,. for lifting a.t least. some.. of the disturbed asphalt away from the wearing surface temporarily and for mixing the: heated aggrecate, bitumen and asphalt; and a. screed for spreadihg and tamping the mixed heated aggregate, bitumen an.d asphalt wherein the heater array, mixe.r and screed are, arranged lmeafly and mounted to a singl.e machine so as to pass over the, wearing course in the order recited as the machine moves in a forwd. direction Such an arrangement allows a single machine, which can be controlled: and. driven, by a single operator, to drh.e along a longitudinal, joint and to y* out most of the: procees necessan, to repair the joint in a single oass (4 machine would be preceded by workmen removing any cat's eyes or the like, and followed by a road roller providing fl'nal compaction of the repair) in a much quicker and less obstructive method than either of the traditional methods of longtucmal reoar Preferabry tne predetermined Cstarce s sign&antlv less than the width of a road wearing ecurse, or caniageway, such as less than about im. This 3ü allows the heater array. mixer and soreS to be mounted to a single machine, which can be stesrad reatively sasdy along the joint under epar. The entire hnear arrangement can conveniently be disposed on one or other side of the machine, so reducing the amount of road width which is blocked while repair is tnderway to not much mare than. the wid th of the machine. Because the width of the repair is less than about tm, a smaRer road. railer may be used, as there is less width of repair to compact. The gitators may.e even S narrower, about 02m in width for example; because the heater array heats the wearing course sufficiertly to soften the asphalt, the agitator which disturbs the wearing course above and on either side of the joint does not have to be operated with the same power as a conventional cold planing device. Instead, it merel' combs through the softened wearing course, causing the asphalt to crumble but not breaking or smathing the individual pieces of IA) aggreodte, tms s advantageous, because this cfsturbed asphalt can then be re-used n the repair process, thus avoiding wasteful use f repair materiaL Mixing of the disturbed sabalt and the sprayed bitumen ts assisted by the lifting of some of this material away from the wearing course. by a significant distance before it is allowed to fail back onto it. The agitators may be cylindrical rollers with teeth or protrusions which are shaped, configured and/or 1.5 diposed. so as. to disturb, lift and/or mix:mehal. as approprIate. Secause the mority of the failures along the length of the longitudinal joint are usually quite minor in extent, the agitatcws need be no more: than about 02m wide, To deal with more e xtens.ive joint falitres, the rollers may be mounted so as to be reciprocabte trahsvere}y to the ilner arrangement.

and to the joint by UP to O4m: in total, thus.ailowing the apparatus to repair more extensive joint failures.

The heater array may comprise several sEparate: heater rtodules, which may be removably mountable on: railing: frames which may be mounted to the. front of the machine and to one or other side to form a Unear array. Rolling frames may be attached to the macblne a d to each othr, and have wheels wblch may be ndependenty steraole so as to 2.5 be able to guide the heaters along parts at the longitudinal joint which are not straight (around bends n tre road, for example The heaters are not subjected to the same stresses in use as are the agitators, so the heaters may be demouiita.ble (for easy and rapid deployment to either side of the machine or disassembly and storage on the machine), however the mixer is preferably mounted securely to the chais or frame of the machine The mixer may comprise, in the diredhon of forward direction of the machine l. USC; a otjmen spray for deposmng neatec bitu rren onto the weanng course, & first agitaar frr disturbing and.iifting the heated asphalt and mixing It with the heated bitumer, a delivery ch.ann& for depositing. heated aggregate onto the wearing course behind the first, agitator and a secon.d agitato.r for mixing the aggregate. with the heated bitumen and the disturbed heated asphalt. Such a mixer can. be relatively small., as it need essenticAy comprise onh. a frame which is sufficienUy robust to hold the agitators. in use, a bitumen spray jet ahead of the first agitator and a. duct for deliverthg aggregate. between the first and second agitators.

There may also be a duct for blowing fibres such as glass fibres onto the wearing course.

between the first and second agitators, for appilcal ions where the specification requires that the: repair be strengthened by such fibra The invention also provides a process for repair ng a Iongitudinai oirt between adthning asphalt iced weannq courses, the process compnsing the successive steos of appiying heat to the surface of the asphalt wearing courses over a predetermined distance tttendhg transverseiy over the joint to raise the temperature of a first predetermined depth of asphalt Ic pred termined temperature; b) spraying heated bitumen onto the heated.

surface; c) agitating the asphaft wearing courses ver a predetermined distance either side of the joint so as mechanicafly to disturb the asphait to a second predetermined depth and to lift at least some of disturbed asphalt away from the wearing courses and at. east partially to mix the heated bitumen wkh the disturbed asphalt, d adding eatoc aggregate onto the at east partiaRy mixed disturbed asphalt and heated bitumen; e) agitating. the heated aggregate, bitumen and the thsturned aspnalt to nx hem zogetner, anc f) speading and tamping the mixed aggregate and aisturbed asphalt above and o either sde of the surface of the joint, this being carried out in a continuous process iong the line of the longitudinal joint. The predétermned distance may preferably be significantly tess than the width of a road wearing course, or carriageway, such as im or less. This is significant because ft. permits the process to be carried out by apparatus mounted on a single machine, The agitators may comprise cylindrical rollers having surce protrusions, so that step c) and/or step e may be carried out. by rotating the rollers with sufficient speed and/or power to.. disturb the asphalt wearing course and to mi the heats aggregate, bitumen and the disturbed asohaft but not so vigomusly as to break the aggregate in tne wearng course ir step c) or, in step a) that aggregate r the aggregate added in step d) Because the agtators may be operated at a relatively Jo speed/power compared to t'e roilors sed in cold planning, the forward speed of the machine car be significantly increased, up to about 1200-14001' per aay, compared to repar methods which use cold plannng ana reoair d substantial width of we2 ring surface (La. about the width of the carriageway), which achieve 7-.

about lcOm per day, or manual. repairs which only achieve about. SUm per day; the. process according to the invention allows repairs to be carried: out even more quickly compared. to patci rep&nng (our prototype macline ahows up to about 1200440Dm of longtudnal jont to be repaired per day), thus minimistng disru:tion to road users.. A further advantage of the invention is that it permits the repair to be. of exactly the same specification as the original wearin.g course; this is achieved firstly by re-use of at least part of the oriçinal asphàll, and secondly oy usng aggregate rn step d) of the same specWcahon as n the ongilel wearng course and by adding that aggregate, and the bitumen in ste.p b), in imflar proportions as were used in the original wearing course. This means that., rather than repairing a failed to singl oint with a repair which has two edges which each form' joints which are as susceptibe to early failure the original joint, the repair is effecthey a seamless. joint of: untform matera speoficabon the same as that o tie ongnal wearng course spec&ato overlying the original. Longitudinaf joint and knitted seamlssLy to the wearing course or.

either side of the repair (which has also been heated by the machine). The rollers may be orwen so as to contra-rotate, wth such an arrangement the first roller beas up the wearing course and begins the mixing of the disturbed asØ.halt and the bitumen as' some of these materials are carried up and over the roller and deposited, in front of the, second rc.iier.

The second rorer then combs through these matei als and the newv-deposzed aggregate, mixing them thorou.ghiy across the width of the second roller and staring to ievel the surface ahead. of the creed, The second predetermined depth may be less than the first. predetermined depth, which is normally about 53mm. This. allows sufficient, heat to be applied to permeate most or all of the wearing cours whiLst only the asphalt wea.rin,g course is disturbed; the und,edying structural road base layer may be heated, so as to weaken the adhesion of the wearing course thereto but preferably that underlying layer is not disturbed. Consequently, the second redeterrnined depth may be approxmately the sa ye as, or si hdy ess thQn»= the depth of' the asphalt surface course of the wsring. courses either side of the joint, nonmally a little less than about 50mm.

BRIEF DESCRIPTION' OF ThE DRAWINGS

30' The invention wfll now be described by way of example, and with' reference' to the: accom'paying flgures, in which: Fi:ure i is an.Hlustrabve side view of an. apparatus in accordance with the invention; Figure »= is a sctematic plan view of the apparatus of Figure 1 *fr the. process of repairing a longitudinal joint; Figure a is a schematic plan view of a mixer forming part of the: apparatus çf Figure S Land Figure 4 is a pertpective view of a heater forming part of the apparatus of Pigure 1.

DETAILED DESCRIPTION OF THE EMBODIMEN IS

Figure 1 shows a k.ngitudinal joint repair machine 10 having a cab 12 (containing a drivert; seat driving controls and controls for the various devices forming part of the. repair apparatus) and arranged to be driven forwardly, when in use for repair, in the direction of the arrow F, There are shown 4 heaters 1., 2, 3, 4 arranged in a. linear array in the d:irection F (although we prefer to use it ore heaters, .8 in our prototype. only four are shown, for iflustadon); the heaters are further described below, in connedicn with Figure 4. Each heater is supported by at least two hanging supports 16 (for darity only one is referred in the drawing, at the front of heater.3, and those for heater 4 are omitted to allow the large rear wheel of. the machine to be seen); the hanging: suppor 16 depend from either a hanging bem 18 which is.a s ecured to the chassis of the machine IQ or from roWng frames 20. Each rolllng. frame 20 is removably attached to the front of the machine, eithc.r c.irecdy (as. in that holding heater 2). or indirectiy via the front: of a preceding rolling frame (as in that holding heater 1), and has wheek (not shown) to support the weight of th.e heater and. so as to avoid, the sfrains which. a cantilevered arrangement. would otherwise place on the attachments between frames and between the frame and the inachina At. the rear of the machine tO is a conventional heated scree. 22. Between the rearmcst heater 4 and the screed 24 is a mixer 26. (described further below in connection with Agure 3, but lustrated n Agure 1 by two circles reoresenting two cyl ndncal rol ci agitators in end view), wtich is fed with aggregate from a conyenth.n& hot material hotbox 28, wtiicb n turn is supplied wth gas for heatnç the aggregate from an o'-boat gas supply 30. The machine. 10. is adapted. to carry the heaters and the rollfrç. frames when these are demounted from the front of the machine, as shown generaVy at 34.

Figure 2 shows the machine 10 schematically from above, in the process of repairing.

a longitudinal jOint.36 extending between th.e hard shoulder 40 and the first, or inside, i:ane 42 of a: three lane motorway (there is a middle lane 44 and. an outer lane 46, there being similar longitudinal joints between each of these, as indicated by the dotted hnes, and on the outside of the outside lane 46 there is a barricr 4. between the two opposing cardagewa). Also on the machine 10 there is a bitumen suoply 50 which feeds bitumen to the mixer 26 via the hotbox 28 in known fashion. The floe cf the joint beh)nd the.. machine is indicated at 52, though in pactice tnis ine would oe very nthstinct, because repa N accordance With the invention produce an essentially seamless join, and there is a road roller 54 which compacts tte repaired joint in the conventional manner.

Figure 3 shows schematically in p view the mixer 26 this consists of a frame 60 which has journals to support for first and second shafts 62, 64 to rotate about axes A, A' respective (as shown by the curved arrows), and which carry first and second cyfindrical agftato' rohers 66, 68 respect vely The curved surface of each roller 66, 68 is proviact w'tb protrusions 70 (for.cladiy only 2 are shown, in the form of conical studs, however the protrusions can be of any form which is sullae for th purposes of disturbing and. lifting the heated asphalt (carded out by roller 66) and for mixing (roller 68)).. In use, the mixer is d:riven along the longitudinal joint, being repaired in the direction of arrow F. the asphalt.

over and either side of the joint having been heated by. the preceding heater array. Heated bitumen is sprayed from a slot-style spray jet (not Shown) onto the. road surface 72 in advance of the first roller 66; the jet. altows for bitumen emulsion (polymer modified, cationic or anionic) to be introduced as requ.ired The bituminous: material needs to be heated to a temperature of eighW degrees: centigrade or higher. Thi.s is achieved using a conenUonal.eiecthcal.l.y powered immersion prong fitted into the centre: of the bitumer supply tank 50. The flow cf bitumen to. the jet is controlled: via a hydraulically driven positi.e displacemert pump knot shown) adiacent to the heated bitumen tank 50 The speed of flow of bitumen s controllea by i'creasng or decreasng the hydraulic oil pressure fcednç the pump As. the machine 10 progresses forwards, the first roller 65 disturbs or scarifies the wearing course either side of the joint and also mixes the sprayed bitumen With the disturbed material to an extent. The first roller 6 rotates in the opposite direction to the direction of movement of the vheeis of the mathine. 10 so that, as the machine moves fdflva:rd, the teeth 70 break up the wearing course and lift some cf the distuited a. phait aic tie soraved btmen up and over the roller, whch furthe-mixes te thsturoed asphat material with the: heated bitumen the.: matedais which are carried. over the. roller 66: re then deposited back onto the road surface (the materials do not adhere to: the roUer 6 or the teeth 70 because they are at.a sufficiently elevated temperature). Next, a conventionai auger not shown) supplies eatS aggregate from the hotbox 28 to the roao surface 74 between the first 66 and second roller 68 (which are about 024rn apart and about 02rn in width), and as the niachine continues moving fOrwardly the second roller 69 mbes the disturbed asphalt, the bitumen and the newlyiupplled aggreç ate; we prefer that the second rollEr 69 is driven so a to contratrOtat relative to the first roller 66, as thi ptomotes better mbdng an.d also helps level the mixture of heatec. materials in advance of the screed 22. The rotation and movement of both. rollers are independently governed by hydraulic m.othrs, mounted to the chassis of the machine 10 v/a hydrai,41c hoses. AS is known., a town ter controls the resultant speed of rotation, of each roller by increasing or decreasing the. flow of hydraulic el to the motor. The mixer 26 is secured to the chassis of the machine, so as to vhstand tie stresses resulting from ooerator of the rolles 66, 68, however, the frame $0 may be mounted so as to be movable reciprocally as indicated by the arrows R (or the sha 62, 64 may be movable within the frame 60 journals in the same direction), so that the rollers can operate over a greater width (up: to about Dim either side). It is preferred that th.e frame 60 reciprocates, because it takes with. It the bitumen spray jet and the aggregate feed Sc: that these are equally spread over the width. of the repair As is convEntional, the repaired. wearing course is then spread and tampered by the heated screed as the machine 10 continues moving forward, and then compacted flnally by the road roller 54.

Figure 4 shows one of the heaters 1 (the others are similar), from Figure 1 in greater detaii The heater I (measuring about 2m x im. x 05Pi) has attachments B for reieasabie attach.r cot to hangers 16., and contains a computer controlled g feed utiliing a ferrochrome alloy as a methum to pulse heat into the road surface This pusing methoa causes the asphalt to rnaintar a constant heat and therefore al ows a cvstenatic aid 0 controlled heat enirornient to oe created across the treatment area -I 1-The machine 10 moves forward at a variable speed. to. achieve, the optimum temperature for the material content of the aiea to be treated:.. This is achieved across a Im wide area of the treatment patch. Screed end temperatures. are dependent on the road surface temperatures and moisture content at the: tim.e of applying the process. The S temperature achieved adjusts the forward motion f: the machine. The process is controHed by mc.nitori'ng the wearing course surfcE temperature aiong the beating. train. Additionally, the temperatures of the bitumen to be sprayed and of the aggregate in the hotbox are monitored. This information is received by on board computer which. hdicates to the operator what adjustments are required Th forward speed of the machine 10 (whith is mainly determined by the temperatures sensed frr mediately behind heater 4. arId the agitator 26) and the output temperatures of the indnndual heaters (wh cii are ma nv determined by the nature of the wearing course and the. depth to which it neeas to be.

heated. to. effect the repair) Each indM&al heater 1 2,: 3, 4 is coupled to a ten peratu.re sensor continually giving a reading r degrees cenhgrace of the output of the uiit Ths is monitored by central computer which can increase or decrease. the heater outputs in degrees cenugrade by increasing or decreasing the flow of LPG from the supply 30 to the heater.

It will of course be undertoo4 that. many variations may be made to the above described embodiment without departing from the scope of the presen. iivwtior For example, the invention: has been described in connection with longitudinal joints i.n mads howevw the invention is appicable to any aspha1t surface having gene-aJ', hnear joints, such. as runways, joins where trenches. have been cut. in roadways for the purpose of accessing seniices under the road (such as water, gas or electricity services) and the R.ke The invention has been described, for the repair of jcdnts between adjacent wearing courses, but it w:iH be apparent to those skiiled in the art that. it could also be. used at the edge of a single wearing. course, such as the edge of a roadway, or between a. roadway and a:kerb As mentioned above, the heaters forming the Finear array may be mcunted to either side of the machine; it is not envisaged that the mixer may be easily movable, because it has to be securely mounted the machine chassis to withstand the stresses reeultirig from operation of the agitator roilers and to make. the mixer reciprocate the. fuil width of the machine may teuirC excessive suDpo.rting structure; we prefer, if the machine is. to be used fm repairing on either side, to provide two mixers, one on either side. As mentioned above; provision may oc mace to supply glass fibres to be mixed in Mth the repair Glass fbre wools are -4.

stored, on the machine 10, and may be fed into a cutting device via a staInless steel hollow feed pipe to cut the fibres to the specified length, The cutters are switched on or of using an ar feed from the on-board compressor, and the cut, fibres are fed rn a blower for adding to the mixture at 74. We have described how a reciprocating mechanism could enable Dim roUers to re: air a çreater width (up to about OSm., the maximum distance being limited by the width of the heaters); those skilled in the art will understand that, the mixer frame 50 could be made wider, so as to accommodate rollers of different widths, In addion to the control process described above, the apparatus could be equipped. with a GPS system to ensure that the machine accurately follows the longitudinal joint long its length. The.

a protrusions 70 preferably extend far enough from the cyufldricS surface of the rollers to carry out their function (e.g. if they are to disturb. or comb the surface to a depth of 50mm then they., should be' at east 50mm in length;' the protrusions may be'' fitted rele'asably' to the ol ers (e g. screweo into threads in the roller) so that they may be easft cnarged whe then become worn, or exchanged for protrusions of' a different size and/or shape Furthermore where different vanations or alternative arrangements are descnoed above, z should be understood th't embodiments' of the invention may incorporate suci.. variati'cns and/ar alternatives in any suitable combinatiprt

Claims (5)

1. CLAIMSApparatus for repairing a ongitudkul jofrt between adjSning asphalt road wearing courses the apparatus comprising a heater array for heating the surfaces of the asphalt wearing courses on both sdes of the joint, a mixer for deposPdn bitumen S and heated aggregate onto the heated surfaces and having agitators for mechanically disturbing the heated asphalt over a predetermined distance extending transwsey over the joint, for kfting at east some of the thsturbed asobalt awe, from the weating surface and for mixing the heated aggregate, bitumen and asphait, and a streed for Spreadin nd tanlpinç. the mixed heated aggregate bitumen nd asphalt, wherein the heater array mixer and screed are arrag llnc.rly and mounted to a single movable machine so a to pass over the wearing course in that order as the machIne moves, in, a. forward. direthon.
2. 2. Apparatus accordihg to CIim, I wherein the predetermined distance significantly less than the width: of a road weatl'ng course, orcarrigeway..

   3 Apparatus according to Claim 1 or 2 wherein the predetermined distance is between Gland 06m 4. Apparatus according Clam, 1. 2 or 3 wherein the width of the heater array and/or the mixer transverse to the inaar arrangement is/are significantly less than that of a road wearing course, or carriageway.5. Apparatus according to Claim 4 wherein the width of the heater mi orSs.6. Apparatus according to Cairn 3, 4 or S wherei.n the width of the agitators is about DIm, 7. Apparatus according to Claim. 6 wherein the agitators and/or the mixer is/are.reciproc&ty movable in the direction of their width, 8. Apparatus according to any preceding claim whereIn the beater array comprises a: pl.urali of discrete heaters, 9 Apparatds accord ng to Clau-n 8 vhere n at east some of te pluraht ot heaters ae removably mountable to the machine.t0 Apparatus. according to Claim. 9 wherein the heaters are removably attachable to roiling frames which are selectably mc untabie to the machine tc form a linear heater array.11. Apparatus according to any preceding clam wherein the mixer comprises, :fl the direction of machine forward drcction, a bitumen spray for depositing heated bitumen onto the v.earing ccurse, a first.agftator for disturbing the heated asphait and mixing it with the heatea bitumen a delivery channel for depositing heated angregate ont.. the wearing course behind the first agitator and a second açitator for mixing the aggregate with the heated bitumen and the disturbed heated ashalt, 10. 12. Apparatus according to Claim 12 Whertin the mixer further comprises a blower for depositing fibres onto. the wearing course between the first and second agitators.11 Apparatus according to any preceding. c&m. wherein the agitators comprise, at least vo generally lindrical rotatable drum having prothisions.14. Aparatus according to daim ±3.herein the rollers are adapted to contra-rotate in use.15. A process for repairing a longitudinal joint between adjOinirig asphalt road wearing courses, the process comprising the successive steps of: a) applying heat to the surface of the asphalt wearing courses over a predetermined distance extending transversely over the joint tc. raise. the temperature. of a first predetermined, depth of asphalt to a predetermined temoerature; b) spraying heatS bitumen onto the heated surface.; c) agitating the asphalt wearing courses. over a predetermined distance either side of the joint so as mechanically to disturb the asphalt to a second predetermined depth and to lift at least some of disturbed asphalt and at least partially to mix the heated bitumen. with the disturbed a.spalt and to return the at least partiauy mbed asphalt and bitumen tp the surface of the wearing course; d). adding heated aggregate onto the disturbed asphaft. and heated bitumen; e) agitating the heated aggregate, bitumen and the. disturbed asphalt to mix them toqether, and f) sp.reacing and tamping the mixed aggrega te and disturbed asphalt above nd on either side of the urface of the joint, 16. A process according Claim 15 wherein the. predetermined dLstance is significantly ess than the width of a road wearing course, or carriageway.17> A process according to Cairn 16 wherein the predetermined distance is im or less.18. A process according to any of Cairns 15, 16 o.r 17 wherein the agitators comprise cvhndnca rollers havpig surface protrusons, and wherer step c) andor step e) s carried. cut. by rotating the rollers with su:ffident speed andior power to. disturb the bitumen sprayed asphaft wearing course and: to lift at least same of this, and to mix the heated aggregate, bitumen and the dsturoed aspnalt bt iot so vgorousl dS to break aggregate in the wearing course -, in step e) to break that aggregate or th.e aggregate added in step d).19 A process. according to Cairn 18 comprising drMng the roRers so that they contra-rotate..2Q A process according to any of Cairns 15 to 1.9 wherin the second predetermined.ceptn s less thai the first predetermned depth 21 A process accoroing to Oam 20 wheren tie seconc predetrrrined deoth s a.pprpXmatiy the same, as the depth of th asphalt surface course of the wearing courses.22. Apparatus substantially as hereinbefore described and v4th reference to the accompanying drawipgs.23, A process substantially as hereinbefore desc:ribed and with reference. to the accornparwing drawings.Amendments to the claims have been made as follows:CLAIMS1. Apparatus for:repirin a longitudinal loint.betwen adjoining aphait road wearin rourses, b-c apparatus comp(sng a leater aria'1 for heatng the styfarec oL the asphalt wearing courses on both sides of the joint, a mixer thr depositing bitumen and heated. aggregate onto the heated s:uitaces and having. agitators for mechanicafly disturbing the heated asphalt over a prec etermined distance extending transversely over the joint, for lifting at leas some cf the disturbed asphalt away from the wearing sutace and for mixing the heated açgregate. bitumen and asphait and a screed for spreading and ta:mping the mixed heated aggregate. bitumen and to asphaR, whereir the heater aray, mixer and screed are arranged linearly and mounted to. a single movable machine so as to pass over the wearing course In that order as: the machine moves in a forward direction, and wherein the entire linear arrangement is disposed one or other side of the machine.. IC)2. Apparatus according to Claim 1 wherein the predetermined distance. :5 significantly less than the width f a road wearing course, or carriageway.
3. 3. Apparatus according to Clai,m 1 or 2 wherein the predetermined distance is heeen CO 0.2 and 0.5th.
4. 4. Apparatus according to Cairn 1, 2 or 3 wherein the width of the heater:artay and/or the mixer transverse to the Unear arrangement is/are significantly less than that of a 20: road wearir coure, or carriageway.
5. 5. Apparatus according to Cairn 4 wh:erain the width of the heater array is Irn or less, 5. Apparatus according to Claim 3, 4 or S wherein the wicth of the agitators. is about D..2m, 7. Apparatus according to. Claim. 6 wherein the agitators and/or Ue mixer is/are reciprocally movable in the direction of thei.r width.8.. Apparatus according to any preceding claim wherein the heater array comprises a plurality of di%rete heaters.9 nparatus accordrng to Clam S wherein at least some of the oLwal1tv of heaters Cw rerncvably mountahie to the machine, 10. Apparatus according to Claim 9 wherein the heaters are removably attachable to rolling frames wNch are selectably mountable to the machine to form a linear heater a.rray ii. Apparatus according to any preceding. claim, wherein the mixer co.rnp.dses in the direction of machine forward direcdon. a bitumen spray fo deooitihg heated btumer' onto the weanng course a fIrst agaator for d&urthrig the heated asgna t and mixing it with the heated bitumen, a delivery channel r depositing heated cogregate onto the. wearing, course behind the first. gitor and a second ag.itatçr for mixing the aggregate with the heated bitumen a.r.d' the disturbed heated. asphaft.12. Apparatus according to Claim 12 whern the.rnxe.r further comprises a iower fi IC) deposWng flbres onto the weañng course between the first and seco nd agitators.13. Apparatus accoting to any preceding ch'i:m wherein the agftators comprise at least two generally.cØindrcaF rotatable drums having protrusions.14::atu5 accorthnç to Claim 13 wreren the rollers are adapted to cont arotaze n 15. A process for repairing a longitudinal joint between adjoinina asphalt road weadng courses, the process cornpsng the successve steps of a) applying heat to the surface'. Qf Ula shalt wearing courses over a predetermined distance exte Ins transversely over the joint to rse the :tem'perat:ure of a first predetemiined depth of asphalt to a predetermined temperature; h) sprayinG heated bitumen onto the heated surface; c) agitating the asphalt wearing courses over a predetermined distance either side of the joint so as mechanically to disturb the asphalt to a second preaetenmnec depth ard to lift at east some of dsturbec asphat arc at least partially to mix the heated bitumen with the disturbed asphalt and. to return the at least partially mixed asphaLt and bftunien to the surface of the wearing cc..urse; d) adding. heated aggregate. onto. the disturbed asphait and heated btunen; a) agitating the heated aggregate, bitumEn and the disturbed asphait to t& S them together, and spre ding and tamping the mixed aggregate and disturbed asphaft above and on either side of the surface of the. joiht.16. A process according to Cairn IS wherein the predetermined distance is significa.ntiy ess. than the width of a road wearing course, or ca.rriageway.17. A. process according to Claim 16 wherein the predetermined distance is Im or ess.IC) 18. A ptocess according to any of aaims 15,. 15 or 17 wherein the agitators. comprise cyhndricai oRers having 5urface protrusions, and wherein step c) and/br step a) is carried out by rotating the rollers with suffiddnt speed and/or power to disturb the O bitumen sprayed asphaft wearing course and to lift at least some of this, and to mix the heated aggregate, btumen and the dsturbec asphax but not so vgocnuctV as t' O break aggregate in the wearing course or in step e), Ia break that aggregate or the aggregate added in step d) 19. A process accoing Claim 18 comprising driving the rollers that they co.ritra-rotate, 20. A process according to. any of Claims 15 to 19 wherein the second predatE. rrnineci depth is less than the first: prederrnined depth.21. A process according to Cairn 20 wherein the second predetermined depth iS: approxinteiy the same as the depth of the asphalt surface. course. of the wearing courses, 22 Apparatus substantially as herebtefore described nd with reference to the accompanying draw...ing:s 23. A process substanfially as he enb&ore descrthed and wfth reference to the accompanying drawings, IC) Co