EP2640898B1

EP2640898B1 - Method and apparatus for repairing a road surface

Info

Publication number: EP2640898B1
Application number: EP11791037.2A
Authority: EP
Inventors: Richard Jackson
Original assignee: Velocity UK Ltd
Current assignee: Velocity UK Ltd
Priority date: 2010-11-20
Filing date: 2011-11-21
Publication date: 2015-09-23
Anticipated expiration: 2031-11-21
Also published as: WO2012066362A1; GB201019732D0; EP2640898A1

Description

The present invention relates to a method and apparatus for repair of road surfaces and relates particularly, but not exclusively to the repairing of defects such as potholes, cracks, crazing and stripping by a velocity patching process. It should be noted that throughout this application use of the term "road surface" includes all forms of road and highway including motorways, trunk roads, minor road and includes all similar surfaces including, but not limited to, pavements, car parks and hard standing areas.
In the velocity patching process of the prior art, a stream of crushed aggregate (small stones or gravel) coated with an adhesive or binder, such as an emulsion of bitumen in water, is discharged from a nozzle into a defect at a sufficiently high velocity to ensure compaction of the discharged material in the defect.
Equipment for carrying out the process typically comprises a vehicle-mounted hopper for holding a supply of aggregate, a tank for holding a supply of emulsion and a combustion engine driven air blower to produce a high velocity airstream. A flexible hose is also provided with an eductor for delivering aggregate into the high velocity airstream as it travels along the hose which terminates with a nozzle. Finally, an emulsion spray system is provided for coating the aggregate prior to its discharge from the nozzle.
Typically, the prior art process of repairing a defect in a sealed road surface by the velocity patching process comprises the steps of:

(i) directing a stream of air from the nozzle into the defect to displace any debris and water;
(ii) adding emulsion to the air stream from the nozzle to apply a tack-coating of emulsion over the surface of the defect;
(iii) supplying a stream of aggregate to the eductor for incorporation into the airstream from the blower and coating the stream of aggregate with emulsion before it leaves the hose via the nozzle;
(iv) directing the stream of coated aggregate to fill the defect; and
(v) optionally, when the defect has been filled, a coating of dry aggregate and/or sand may be applied to its top surface via the hose and nozzle.

Although the systems of the prior art provide significant advantages over hot-mix asphalt, the prior art systems suffer from disadvantages including inefficiencies in energy usage, waste of materials and noise. Furthermore, such systems also suffer from high wear on all components that come into contact with the aggregate when it is travelling at speed.
Preferred embodiments of the present invention seek to overcome the above described disadvantages of the prior art.
US 2009/274515 discloses an apparatus according to the preamble of claim 1.
According to a first aspect of the present invention, there is provided an apparatus for repairing a road surface, the apparatus comprising:-

a delivery device having a plurality of inlets and at least one exhaust;
air delivery means for delivering a stream of air, having an airstream speed, to at least one first said inlet;
aggregate delivery means operable in an active mode for delivering aggregate to said airstream via at least one second said inlet and in an inactive mode where aggregate is not delivered to said second inlet;
adhesive delivery means operable in an active mode for delivering adhesive to said airstream via at least one third said inlet and in an inactive mode where adhesive is not delivered to said third inlet; and
airstream speed adjustment means for varying airstream speed in response to at least one of the activation and deactivation of at least one of said aggregate delivery means and said adhesive delivery means;
characterised by an engine driven vehicle and wherein said air delivery means comprises at least one variable displacement pump driving at least one hydraulic motor driving at least one blower.

By providing air stream adjustment means and varying the air stream speed upon activation or deactivation of the aggregate delivery means and/or adhesive delivery means, the advantage is provided that the quality of the repair undertaken is improved and the efficiency with which the repair is made is also increased. In particular, varying the air speed provides the optimum air speed for each operation. As a result, in the initial step of cleaning the defect, high speed air is used to ensure that the defect is cleaned efficiently and effectively. In the second stage of the process, a bond-coating of bitumen emulsion is applied to the defect and at this point the air stream speed is preferably reduced to ensure that the bitumen emulsion is sprayed within the defect and so there is no overspray as this can be a hazard to passing vehicles and pedestrians. In the third stage as aggregate is introduced, the speed of the air stream is adjusted to a speed between that for applying bitumen only and used in the cleaning step. Finally the air speed can be increased again when the defect filling has been completed and a final cleaning step is undertaken. Furthermore, by controlling the airstream speed the process is more automated reducing the likelihood of the incorrect button or switch being operated out of sequence resulting in a reduction in the life span of the repair.
By using a variable displacement pump driven by the engine of a vehicle, the advantage is provided that the creation of the air stream, which is the part of the process requiring the largest amount of energy, is achieved very efficiently. In particular, the vehicle can operate from a single engine extremely efficiently, for example, on arrival at the repair site, the driver simply stops the vehicle moving and engages the engine with the delivery device without the need to start a separate engine. This is not only efficient in terms of the time taken but also in the fuel used since inefficiencies in starting and stopping engines and warming and cooling engines are eliminated.
In another preferred embodiment, on activation of said aggregate delivery means a rate of aggregate delivery into said airstream increases from zero to a required rate and said airstream adjustment means increases said airstream speed during said increase in aggregate delivery rate.
By increasing the speed of the air stream as the rate of aggregate delivery increases, the advantage is provided that the waste of aggregate is reduced. In particular, when aggregate is first introduced into the air stream, a small amount of aggregate is added to the high velocity air stream. As a result, these few particles of aggregate absorb a large amount of energy from the air stream and accelerate very quickly to a very high velocity. This velocity exceeds the ideal velocity for adhesion to a road surface and as a result it is common for the first particles of aggregate that are added to the air stream to simply bounce off the road surface and not adhere to the bitumen emulsion. However, as the number of aggregate particles entering the air stream increases, the acceleration and final velocity of each particle is not able to reach the same velocity as the first few particles. By increasing the air stream speed, from the lower speed used in the bond-coating stage, as the aggregate particles are initially added to the air stream, the advantage is provided that the aggregate particles leave the device generally at a consistent and ideal speed and are less likely to bounce off the road surface and be wasted. Aggregate waste is not only important in terms of its cost in materials but also because excess aggregate can cause a hazard on the road surface. Loose aggregate particles cause a skid hazard and single aggregate particles, or clumps of particles bound together, can cause damage to vehicles or other property and injury to pedestrians or other road users if flicked into the air from the road surface. Local authorities often have a duty of care to ensure roads are kept clean and minimise the chance of injury.
In a further preferred embodiment the airstream speed adjustment means increases the air stream speed when said apparatus is being used in a cleaning mode and said aggregate delivery means and said adhesive delivery means are inactive.
Increasing the air speed during a cleaning mode provides the advantage of the quickest and most efficient cleaning before and after the repair has taken place. This is achieved most effectively by opening a valve from a hydraulic pump and increasing the output from the displacement pump to the hydraulic motor which powers the blower. This is more effective than narrowing the cross-section of the exhaust to increase the speed of the air stream on exit. Although this method would increase the velocity, the volume per unit time remains the same thereby not increasing the efficiency of the cleaning step.
In a preferred embodiment the airstream speed adjustment means decreases the air stream speed when said adhesive delivery means is active and said aggregate delivery means is inactive when the apparatus is being used in a bond-coating mode of the repair process.
By decreasing the air stream speed to only bond-coating mode provides the advantage that splattering of the bitumen emulsion is reduced, thereby reducing waste.
According to another aspect of the present invention, there is provided a method of repairing a road or pavement surface, the method comprising:-

controlling the activation and deactivation of air delivery means for delivering a stream of air, having an air stream speed, to at least one first inlet in a delivery device having a plurality of inlets and at least one exhaust;
controlling the activation and deactivation of aggregate delivery means for delivering aggregate to said airstream via at least one second said inlet;
controlling the activation and deactivation of adhesive delivery means for delivering adhesive to said airstream via at least one third said inlet; and
varying said airstream speed in response to at least one of the activation and deactivation of at least one of said aggregate delivery means and said adhesive delivery means;
characterised by using at least one variable displacement pump to drive a blower to create said airstream.

In a preferred embodiment, on activation of said aggregate delivery means a rate of aggregate delivery into said airstream increases from zero to a required rate and said airstream adjustment means increases said airstream speed during said increase in aggregate delivery rate.
The method may further comprise increasing the air stream speed when said aggregate delivery means and said adhesive delivery means are inactive and being used in a cleaning mode.
The method may also further comprise decreasing the air stream speed when said adhesive delivery means is active and said aggregate delivery means is inactive being used in a bond-coating mode of the repair process.
Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense, with reference to the accompanying drawings in which:-

Figure 1 is a schematic representation of the apparatus of the present invention;
Figure 2 is a perspective view of a vehicle carrying the apparatus of the present invention;
Figure 3 is enlarged perspective view of a portion of the vehicle of Figure 2;
Figure 4 is a sectional view of a portion of the apparatus of Figure 2;
Figure 5 is a graph of airflow speed against time during the operation of the device of the present invention;
Figure 6 is a schematic plan view looking into a hopper used in the apparatus of Figure 2; and
Figure 7 is a sectional view of an eductor forming part of the apparatus of Figure 2.

Referring to Figures 1 to 4, 6 and 7, an apparatus 10 for repairing a road and/or pavement surface includes a delivery device 12. The delivery device has a plurality of inlets, 14, 16 and 18 and an exhaust 20. The delivery device 12 also has an eductor portion 22 and flexible duct or pipe portion 24. The eductor portion 22 and pipe portion 24 are connected at an eductor outlet portion 26. The apparatus 10 also includes air delivery means, in the form of an air blower 28. Typically air blower 28 is driven by a hydraulic motor 29, powered by a variable displacement hydraulic pump 31 which in turn draws its power from vehicle engine 30 via power take off drive 32. Operation of blower 28 is under the control of control processor 34 which controls a first hydraulic fluid valve 33 which forms part of control manifold 35.
The apparatus 10 further includes aggregate delivery means 36 for delivering aggregate, which are crushed aggregate material or other solid granular materials suitable for forming a road or pavement surface, into the air stream through the second or aggregate inlet 16. The aggregate delivery means 36 includes an aggregate holding tank 38 and a conveyor 40 that is able to carry aggregate from the holding tank 38. Conveyor 40 is driven by hydraulic motor 42 which in turn takes power from the variable displacement pump 31 that is driven by power take off unit 32 attached to vehicle engine 30. The supply of hydraulic fluid to hydraulic motor 42 is via a second hydraulic fluid valve 43 in control manifold 35. The second hydraulic fluid valve is also under the control of control processor 34. Aggregate delivery means 36 also includes a hopper 34 that receives aggregate falling from conveyor 40 and directs it through second inlet 16 to the air stream flowing through the eductor portion 22.
Apparatus 10 further includes adhesive delivery means 46 for delivering adhesive, typically a cold bitumen/water emulsion to the adhesive or third inlet 18 along adhesive delivery pipe 48. The adhesive delivery means also includes an adhesive reservoir tank 50 for holding the bitumen emulsion which is maintained under air pressure provided by a compressor. The bitumen emulsion is released from reservoir tank 50 by control of a valve 52. Under the pressure of tank 50 the bitumen emulsion travels along pipe 48 to third inlet 18. Valve 52 operates under the control of control processor 34, but could equally be controlled by a manual valve operated by an operator.
Under the control of processor 34 the aggregate delivery means 36 and adhesive delivery means 46 are operable in an active mode where respectively aggregate and adhesive are delivered into the air stream and an inactive mode where aggregate and adhesive are not delivered through their respective inlets to the air stream.
Referring to Figure 4, the aggregate delivery means 36 is shown in more detail. An eductor portion at 22 has an end 54 that is closed by an end plate. Air inlet 14 extends through end plate 54 to a point just below the aggregate inlet 16. Hopper 44 is Frusto-conical in shape and is joined to a connecting pipe 56 that joins the narrow end of hopper 44 to pipe 58 of eductor portion 22. Connecting pipe 56 and eductor pipe 58 are typically circular in cross section and connecting pipe 56 has a major dimension or diameter indicated at 60. Air inlet 14 extends into the eductor pipe 58 beyond end plate 54 by a length indicated at 62. Length 62 is preferably less than 30% of diameter 60, is more preferably between 20% and 30% of diameter 60 and is ideally 25% of diameter 60. It will be apparent as seen in Figure 6 that the air inlet is located directly below the aggregate inlet resulting most efficient transfer of aggregate to the airstream. In the embodiment shown in figure 6, because the hopper leads directly into the linear aggregate connector pipe 56 the air inlet 14 is visible through the aggregate inlet 16.
Operation of the apparatus will now be described with additional reference to Fig 5. Vehicle 64 that is carrying repair apparatus 10 arrives at a site requiring repair, parks but leaves engine 30 running. The operator switches the vehicle engine using control of processor 34 so that power take off unit 32 drives variable displacement pump 31. The operator also releases supporting arm 66 from its locked condition on the back of vehicle 64 and extends it, as shown in Figures 2 and 3, to support the weight of flexible pipe 24. The operator takes hold of circular gripping handle 68 and operates the apparatus 10 using control input device 70 that is connected via input cable 72 to control processor 34.
The first stage of the operation is the cleaning of the defect in the road or pavement surface. This is achieved by directing a high speed stream of air at the defect to remove any loose debris and any excessive water. The blower 28 is therefore activated at time T1 (see Figure 5) and increases to a maximum speed at time T2. This air stream is maintained during the cleaning phase which ends at time T3.
The end of the cleaning phase is indicated by the operator requesting, via the controlling device 70, the activation of the adhesive delivery means 46. As a result at time T3 the speed of the air stream is decreased by adjustment of the first hydraulic valve 33 decreasing the flow of hydraulic fluid to the hydraulic motor 29 which in turn slows the rotation of blower 28. By altering the output from the pump, the volume of air per unit time is reduced thereby reducing the air stream speed to the speed indicated at T4. The bitumen emulsion is introduced once the air stream speed is reduced to the speed indicated at time T4, this being the ideal speed for introduction of the bitumen emulsion to the defect. The bitumen emulsion provides a bonding-coat layer in the base of the defect which seals the defect and provides an adhesive base onto which the aggregate can stick. The application of the bond coat takes place from time T4 to time T5.
At time T5, once the bond-coat has been applied, the operator indicates, using control input device 70, that the defect is ready for filling with aggregate. At time T5 conveyor 40 is activated using drive device 42 and aggregate enters hopper 44, passes through aggregate inlet 16 and into the air stream as it passes through eductor portion 22. At time T5 the air stream speed increases from the speed applying the bond coat (T4 to T5) to a speed that is less than the speed of the cleaning phase (T2 to T3). This increase in speed accommodates the increase in aggregate passing through inlet 16 which starts at zero and reaches a constant and consistent level as aggregate backs up in hopper 44. The speed of conveyor 40 can be controlled utilising a sensor in hopper 44 to ensure that a consistent level of aggregate is maintained in hopper 44 by controlling the flow of hydraulic fluid through valve 43 in manifold 35, thereby providing a consistent flow rate of aggregate into the air stream through inlet 16. The controlled increase in air stream speed between T5 and T6 ensures that the first aggregate particles entering the air stream are not accelerated to a speed that is too high causing them the bounce off the bonding-coat layer. The airstream speed is increased as the rate of aggregate passing into the airstream increases thereby maintaining a reasonably consistent aggregate particle speed on exit from the apparatus. Aggregate entering the eductor portion 22 passes along flexible pipe 24 and is coated with the bitumen emulsion from inlet 18 that is located adjacent exhaust 20.
The defect is filled with aggregated coated in the bitumen emulsion from time T6 to T7. At time T7 the operator indicates, using control input device 70, that the filling stage of the operation is complete and the aggregate delivery means is deactivated by control processor 34. A small quantity of aggregate continues to pass through inlet 16 and into the air stream. Once this aggregate has passed through exhaust 20 the adhesive delivery means can be deactivated at time T8. It should be noted that the adhesive delivery means can be deactivated at time T7 and this will result in the remaining quantity of aggregate passing onto the repair without being coated in aggregate. This can be advantageous for providing a dry top coat to the road surface.
Time T8 indicates the start of a final cleaning process and the speed of air being blown by blower 28 is adjusted, via hydraulic valve 33 under the control of processor 34, to increase the air stream speed to a maximum indicated at time T9. This continues until time T10 when the operator indicates that the repair is completed and the blower is switched off by control processor 34 the air stream speed then decreases to zero at time T11. At this point the repair is complete and the supporting arm 66 and flexible pipe 24 can be blocked back to the rear of the vehicle. Drive transfers 32 and 43 are disconnected and engine 30 can be used to drive the vehicle 64 the next repair location.
It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not only in limit of sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. For example, other power sources may be used to drive the conveyor 40, the blower 28 and the adhesive pump 52. Other adhesives than a bitumen water emulsion could be used although this has the advantage of minimal environmental impact. It is also the case that other forms of power supply to the various component of the apparatus may be used. For example, power may be provided by a separate engine connected directly to a blower or alternatively to a fixed displacement pump which provides the hydraulic fluid to power the hydraulic motors 29 and 42.

Claims

An apparatus (10) for repairing a road surface, the apparatus comprising:-
a delivery device (12) having a plurality of inlets (14, 16, 18) and at least one exhaust (20);

air delivery means (28) for delivering a stream of air, having an airstream speed, to at least one first said inlet; aggregate delivery means (36) operable in an active mode for delivering aggregate to said airstream via at least one second said inlet and in an inactive mode where aggregate is not delivered to said second inlet;

adhesive delivery means (46) operable in an active mode for delivering adhesive to said airstream via at least one third said inlet and in an inactive mode where adhesive is not delivered to said third inlet; and

airstream speed adjustment means for varying airstream speed in response to at least one of the activation and deactivation of at least one of said aggregate delivery means and said adhesive delivery means;

characterised in that the apparatus comprises an engine (30) driven vehicle and in that said air delivery means comprise at least one variable displacement pump (31) driving at least one hydraulic motor (29) driving at least one blower (28).
An apparatus according to claim 1, wherein on activation of said aggregate delivery means a rate of aggregate delivery into said airstream increases from zero to a required rate and said airstream adjustment means increases said airstream speed during said increase in aggregate delivery rate.
An apparatus according to claim 1 or 2, wherein said airstream speed adjustment means increases the air stream speed when said apparatus is being used in a cleaning mode and said aggregate delivery means and said adhesive delivery means are inactive.
An apparatus according to any one of the preceding claims, wherein said airstream speed adjustment means decreases the air stream speed when said adhesive delivery means is active and said aggregate delivery means is inactive when the apparatus is being used in a bond-coating mode of the repair process.
A method of repairing a road surface, the method comprising:-
controlling the activation and deactivation of air delivery means for delivering a stream of air, having an air stream speed, to at least one first inlet in a delivery device having a plurality of inlets and at least one exhaust;

controlling the activation and deactivation of aggregate delivery means for delivering aggregate to said airstream via at least one second said inlet;

controlling the activation and deactivation of adhesive delivery means for delivering adhesive to said airstream via at least one third said inlet; and

varying said airstream speed in response to at least one of the activation and deactivation of at least one of said aggregate delivery means and said adhesive delivery means;

characterised by using at least one variable displacement pump to drive a blower to create said airstream.
The method according to claim 5, further comprising one or more of the following features:-
a) wherein on activation of said aggregate delivery means a rate of aggregate delivery into said airstream increases from zero to a required rate and said airstream adjustment means increases said airstream speed during said increase in aggregate delivery rate;

b) increasing the air stream speed when said aggregate delivery means and said adhesive delivery means are inactive and being used in a cleaning mode; or

c) decreasing the air stream speed when said adhesive delivery means is active and said aggregate delivery means is inactive being used in a bond-coating mode of the repair process.