Patent Publication Number: US-10774485-B2

Title: Pre-filled adhesive pavement markers

Description:
FIELD 
     The present invention relates to pre-filled adhesive pavement markers and a related method of adhering them to pavement or roadway surfaces. 
     BACKGROUND 
     Pavement and road markings and devices are fixed onto roads, pathways, runways and service areas for a variety of reasons. For example, raised pavement markings (RPMs), raised reflective pavement markings (RRPMs) and other tactile markings are often used to guide and warn road users or delineate reserved areas. 
     RRPMs are advantageous in that they assist warn and guide road users with audible and steering vibration feedback to the driver and they function in inclement weather for example when a roadway is heavily sheeted in water or fog. 
     Bituminous road surfaces are made from composite materials containing rock and emulsion. Road devices are often anchored in place using bitumen-based adhesives or bonding agents, which have the same properties as the emulsion used in the road surface. To install the device, a block of adhesive, or pre-formed adhesive pad, is firstly heated and then applied onto the road surface. The device is then placed onto the adhesive while still hot and optionally rotated and/or moved until the device is in the correct orientation and position. The adhesive is then left to cool and set hard to anchor the device in place. 
     The connection between the device and the road surface can become weak or vulnerable to breakage over time, particularly when the road and device have been exposed to repeated fluctuations in temperature. Bitumen expands and softens in warm temperatures and contracts and hardens in cold temperatures. Changes in ambient temperature, therefore, lead to tension in the road surface and in the adhesive medium connecting the devices to the road surface. Road devices do not expand or contract with the road surface to which they are connected to accommodate such changes. 
     The difference between the surface tensions in an inflexible solid-state road device, the flexible adhesive pad and the as constructed bitumous road surface is, therefore, constantly changing. Prolonged exposure to temperature fluctuations as a result of daily and climatic weather changes eventually leads to breakage of the connection between the device and the surface causing the device to disconnect from the surface. Impacts and wear caused by wheels of traffic exacerbates the weakening of the connection. Road devices that separate, come loose and break away from their mountings can be hazardous, particularly in heavy and fast-flowing traffic conditions. Devices can become airborne causing damage to property and personal injury and, in extreme cases, can have fatal consequences. 
     Great improvements have been made in the manufacture of RRPMs over time such as their Impact strength, ultraviolet protection and reflective properties. RRPMs are commonly manufactured from glass, aluminium or specially formed hardened plastics or polymers and are therefore inflexible. The connection of RRPMs to their adhesive pad and the roadway surface has not evolved nor has it been improved in accordance with road traffic safety or RRPM manufacture. RRPMs are inflexible and they are installed onto a flexible adhesive pad and this connection releases under climatic and road traffic forces. 
     The associated costs in the replacement maintenance and reinstatement of safety delineators due to their adhesive failure rate is a significant problem in the global road marking industry. 
     A need therefore exists for improved solutions for adhering pavement markers to pavement or roadway surfaces. 
     SUMMARY 
     A method, comprising: 
     providing a pre-filled adhesive pavement marker having a body with downwardly facing openings that are pre-filled with an adhesive; 
     providing an adhesive pad of the adhesive on a surface of a pavement; 
     attaching the pre-filled adhesive pavement marker to the adhesive pad to thereby adhere the pre-filled pavement marker to the surface of the pavement. 
     The adhesive used to the pre-fill the pre-filled adhesive pavement marker and the adhesive used in the adhesive pad may comprise the same adhesive so that like-for-like adhesion is provided between the pre-filled adhesive pavement marker and the surface of the pavement. 
     The adhesive may comprise bitumen or epoxy. 
     When the adhesive comprises bitumen, the adhesive pad may be heated before attachment of the pre-filled adhesive pavement marker. 
     When the adhesive comprises bitumen, the bitumen used to pre-fill the pre-filled adhesive pavement marker may comprise a low softening point bitumen, and the bitumen used in the adhesive pad may comprise a high softening point bitumen. 
     The pre-filled adhesive pavement marker may be pre-filled with the low softening point bitumen heated to a temperature between around 250° C. and around 270 CC, for example, around 260° C. This temperature is required to ensure that the viscosity of the bitumen adhesive fills all cavities within the marker and that the bitumen adhesive etches into the markers structural surface which ensures a strong internal bonding between the bitumen adhesive filler and the marker body. 
     The adhesive pad may comprise the high softening point bitumen heated to a temperature between around 210° C. and around 220° C., for example, around 215° C. 
     The pre-filled adhesive pavement marker may comprise any one of a raised pavement marking, a raised reflective pavement marking, and a road stud. 
     The present invention also provides a pre-filled adhesive pavement marker having a body with downwardly facing openings that are pre-filled with an adhesive. 
     The adhesive may comprise bitumen or epoxy. 
     The downwardly facing openings may have a depth no greater than so as to allow the downwardly facing openings to completely pre-fill with the adhesive before the pre-filled adhesive pavement marker is adhered to a surface of a pavement. 
     The downwardly facing openings may be defined by downwardly projecting ribs formed inside the body. 
     The downwardly projecting ribs may be formed in any one of a cross-hatch pattern, a mesh pattern, and a waffle pattern. 
     The body may comprise downwardly projecting peripheral portions, and the downwardly projecting ribs may project downwardly between the downwardly projecting peripheral portions. 
     The downwardly projecting ribs may have a depth less than the depth of the downwardly projecting peripheral portions. 
     The body and the downwardly facing openings may be formed as a moulding of a resilient plastics material. 
     The downwardly facing openings may be pre-filled with the adhesive after moulding and before the pre-filled adhesive pavement marker is adhered to an adhesive pad on a surface of a pavement. 
     The present invention further provides a surface of a pavement comprising a pavement marker adhered thereto by the method described above. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic flow diagram of a method of adhering a pre-filled adhesive pavement marker to a surface of a pavement or roadway according to an embodiment of the present invention; 
         FIG. 2  is a photographic bottom view of a pre-filled adhesive pavement marker according to an embodiment of the present invention showing the open cavities that will be filled with bitumen adhesive prior to installation; 
         FIGS. 3 and 4  are photographic cross-sectional views of the pre-filled adhesive pavement marker; 
         FIG. 5  is a photograph of pre-filled adhesive pavement markers adhered to a roadway surface; 
         FIG. 6  is a photograph of a hydraulic ram used to separate the pre-filled adhesive pavement markers and conventional solid, unfilled pavement markers from the roadway surface; and 
         FIGS. 7 and 8  are photographs of the pre-filled adhesive pavement markers and conventional pavement markers, respectively, after separation from the roadway surface. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic flow diagram of a method  10  of adhering a pre-filled adhesive pavement marker  20  to a surface  32  of a pavement or roadway  34  according to an embodiment of the present invention. The method  10  starts at step  12  by providing the pre-filled adhesive pavement marker  20  having a body  22  with downwardly facing openings  24  that are pre-filled with an adhesive  26 . The pre-filled adhesive pavement marker  20  may comprise any one of a raised pavement marking, a raised reflective pavement marking, and a road stud. 
     Next, at step  14 , an adhesive pad  28  of the adhesive  26  is provided on a surface  32  of a pavement or roadway  34 . The adhesive  26  used to the pre-fill the pre-filled adhesive pavement marker  20  and the adhesive  26  used in the adhesive pad  28  may comprise the same adhesive  26  so that like-for-like adhesion is provided between the pre-filled adhesive pavement marker and the surface of the pavement. The adhesive  26  may, for example, comprise bitumen or epoxy. When the adhesive  26  comprises bitumen, the like-for-like adhesion is provided between the pre-filled adhesive pavement marker and the surface of the pavement may advantageously be at least partially flexible and/or movable in response to varying climatic and impact conditions. 
     When the adhesive  26  comprises bitumen  26 , the adhesive pad  28  may be heated before attachment of the pre-filled adhesive pavement marker  20 . For example, the adhesive pad  28  may, for example, comprise a bitumen block  28  that is melted in a hot melt kettle and poured onto the surface  32 , or bitumen sheet  28  that is blowtorched onto the surface  32 . 
     A bitumen based adhesive is used as an anchoring point to the road surface to produce a flexible connection point that is compatible with the bitumous emulsion in the road. The adhesive bitumen pad is designed to behave in concert with the road and has the flexibility to harden and soften and expand and contract in conjunction with the road surface with climatic variations and changes. 
     When the adhesive  26  comprises bitumen, the bitumen  26  used to pre-fill the pre-filled adhesive pavement marker  20  may comprise a low softening point bitumen  26   a , and the bitumen  26  used in the adhesive pad may comprise a high softening point bitumen  26   b . For example, the pre-filled adhesive pavement marker  20  may be pre-filled with the low softening point bitumen  26   a  heated to a temperature between around 250° C. and around 270° C., for example, around 260° C. The adhesive pad  28  may comprise the high softening point bitumen  26   b  heated to a temperature between around 210° C. and around 220° C., for example, around 215° C. 
     The method  10  ends at step  16  by attaching the pre-filled pavement marker  20  to the adhesive pad  28  to thereby adhere the pre-filled pavement marker  20  to the surface  32  of the pavement or roadway  34 . 
     Referring to  FIGS. 2 to 4 , a pre-filled adhesive pavement marker  20  according to one embodiment of the present invention comprises a body  22  with downwardly facing openings  24  that are pre-filled with an adhesive  26 . The adhesive  26  may comprise bitumen. 
     The downwardly facing openings  24  may have a depth no greater than so as to allow the downwardly facing openings  24  to completely pre-fill with the adhesive  26  before the pre-filled adhesive pavement marker  20  is adhered to the surface  32  of the pavement or roadway  34 . 
     The downwardly facing openings  24  may be defined by downwardly projecting ribs  36  formed inside the body  22 . The downwardly projecting ribs  36  may be formed in any one of a cross-hatch pattern, a mesh pattern, and a waffle pattern. 
     The body  22  may comprise downwardly projecting peripheral portions  38 , and the downwardly projecting ribs  36  may project downwardly between the downwardly projecting peripheral portions  38 . The downwardly projecting ribs  36  may have a depth less than the depth of the downwardly projecting peripheral portions  38 . The downwardly projecting peripheral portions  38  may define a generally rectangular recess. The adhesive  26  may pre-fill the generally rectangular recess up to and including the corners of generally rectangular recess to form a pre-filled base pad of the adhesive below the pre-filled downwardly facing openings  24 . Semi-circular and linear grooves  40  may be formed in the downwardly projecting peripheral portions  38  to provide locating surfaces for the adhesive pad  28 . 
     The body  22  and the downwardly facing openings  24  may be formed as a moulding of a resilient plastics material. The downwardly facing openings  24  may be pre-filled with the adhesive  26  after moulding and before the pre-filled adhesive pavement marker  20  is adhered to the surface  32  of the pavement or roadway  34 . 
     The invention will now be described in more detail, by way of illustration only, with respect to the following example. The example is intended to serve to illustrate this invention, and should not be construed as limiting the generality of the disclosure of the description throughout this specification. 
     EXAMPLE 
       FIG. 5  illustrates pre-filled adhesive pavement markers adhered to a surface of a roadway according to the method described above with bitumen used as the common adhesive. Conventional pavement markers (not shown) with a solid base without any adhesive pre-filling were also adhered to the same roadway surface with epoxy as the adhesive. 
     Both the pre-filled adhesive pavement markers and the conventional solid, unfilled pavement markers were subjected to lateral shear forces from a hydraulic ram fitted with a flat plate and 20 mm chisel edge, as illustrated in  FIG. 6 . The lateral shear forces were applied until the pre-filled adhesive pavement markers and the conventional pavement markers separated from the roadway surface. The preparation parameters, installation parameters, and lateral forces in pounds per square inch (psi) required to separate the pre-filled adhesive pavement markers and the conventional unfilled pavement markers are set out below in Table 1 and 2 respectively. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Adhesive Filled RRPM&#39;s (new model) 
               
               
                 RRPM to Road separation shear force test results 
               
            
           
           
               
               
               
            
               
                 Preparation 
                   
                 Result 
               
               
                 Parameters 
                 Installation Parameters 
                 Shear Force 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Bitumen 
                 Road 
                 Ambient 
                 Bitumen 
                 Required to 
               
               
                 RRPM 
                 Adhesive Fill 
                 Temp 
                 Temp 
                 Adhesive 
                 Separate 
               
               
                 Ref# 
                 Temp (° C.) 
                 (° C.) 
                 (° C.) 
                 Temp (° C.) 
                 (PSI) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 1 
                 220.0 
                 11.0 
                 13.0 
                 218.00 
                 1320 
               
               
                 2 
                 225.0 
                 11.5 
                 13.0 
                 218.00 
                 1650 
               
               
                 3 
                 221.0 
                 11.5 
                 13.0 
                 218.00 
                 1080 
               
               
                 4 
                 226.0 
                 11.5 
                 13.0 
                 220.00 
                 1140 
               
               
                 5 
                 228.0 
                 11.0 
                 13.0 
                 220.00 
                 1050 
               
               
                 6 
                 230.0 
                 11.0 
                 13.0 
                 220.00 
                 1200 
               
               
                 7 
                 230.0 
                 11.0 
                 13.0 
                 220.00 
                 1110 
               
               
                 8 
                 235.0 
                 11.0 
                 13.0 
                 215.00 
                 1180 
               
               
                 9 
                 235.0 
                 11.0 
                 13.0 
                 205.00 
                 1400 
               
               
                 10 
                 238.0 
                 11.0 
                 13.0 
                 220.00 
                 1350 
               
               
                 11 
                 240.0 
                 11.0 
                 13.0 
                 220.00 
                 1480 
               
               
                 12 
                 242.0 
                 10.5 
                 12.0 
                 220.00 
                 1250 
               
               
                 13 
                 245.0 
                 10.0 
                 12.0 
                 220.00 
                 1350 
               
               
                 14 
                 250.0 
                 10.0 
                 12.0 
                 220.00 
                 1180 
               
               
                 15 
                 253.0 
                 10.0 
                 12.0 
                 218.00 
                 1230 
               
               
                 16 
                 258.0 
                 10.0 
                 12.0 
                 218.00 
                 1180 
               
               
                 17 
                 262.0 
                 9.5 
                 11.0 
                 205.00 
                 1050 
               
               
                 18 
                 273.0 
                 9.5 
                 11.0 
                 218.00 
                  950 
               
               
                 19 
                 275.0 
                 9.5 
                 11.0 
                 218.00 
                 1020 
               
               
                 20 
                 280.0 
                 9.5 
                 11.0 
                 220.00 
                 1250 
               
               
                   
                   
                   
                   
                   
                 1221 Avg 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Unfilled/Hard Base RRPM&#39;s (old model) 
               
               
                 RRPM to Road separation shear force test results 
               
            
           
           
               
               
               
            
               
                   
                 Installation Parameters 
                 Result 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 Bitumen 
                 Shear Force 
               
               
                 RRPM 
                 Road 
                 Ambient 
                 Adhesive 
                 Required to 
               
               
                 Ref# 
                 Temp (° C.) 
                 Temp (° C.) 
                 Temp (° C.) 
                 Separate (PSI) 
               
               
                   
               
               
                 21 
                 9.5 
                 11.0 
                 220.00 
                 440 
               
               
                 22 
                 9.5 
                 11.0 
                 220.00 
                 455 
               
               
                 23 
                 9.5 
                 11.0 
                 220.00 
                 420 
               
               
                 24 
                 9.0 
                 11.0 
                 220.00 
                 450 
               
               
                 25 
                 9.0 
                 11.0 
                 218.00 
                 460 
               
               
                 26 
                 9.0 
                 11.0 
                 218.00 
                 430 
               
               
                 27 
                 9.0 
                 11.0 
                 218.00 
                 450 
               
               
                 28 
                 9.0 
                 11.0 
                 218.00 
                 440 
               
               
                 29 
                 9.0 
                 11.0 
                 217.00 
                 475 
               
               
                 30 
                 9.0 
                 11.0 
                 217.00 
                 430 
               
               
                 31 
                 9.0 
                 11.0 
                 216.00 
                 455 
               
               
                 32 
                 9.0 
                 11.0 
                 216.00 
                 465 
               
               
                 33 
                 9.0 
                 11.0 
                 217.00 
                 440 
               
               
                 34 
                 9.0 
                 11.0 
                 219.00 
                 470 
               
               
                 35 
                 9.0 
                 10.0 
                 219.00 
                 450 
               
               
                 36 
                 9.0 
                 10.0 
                 219.00 
                 470 
               
               
                 37 
                 9.0 
                 10.0 
                 220.00 
                 440 
               
               
                 38 
                 9.0 
                 10.0 
                 220.00 
                 460 
               
               
                 39 
                 8.0 
                 10.0 
                 220.00 
                 460 
               
               
                 40 
                 8.0 
                 10.0 
                 219.00 
                 445 
               
               
                   
                   
                   
                   
                 450 Avg 
               
               
                   
               
            
           
         
       
     
     The average lateral shear force required to separate the pre-filled adhesive pavement markers from the roadway surface was 1221 psi, whereas the average force required to separate the conventional pavement markers from the same roadway surface was 450 psi. The conventional pavement markers therefore have only 37.7% of the like-for-like adhesion of the pre-filled adhesive pavement markers of the present invention. This is visually indicated in  FIGS. 7 and 8  by photographs of the pre-filled adhesive pavement markers and conventional pavement markers, respectively, after separation from the roadway surface. 
     Embodiments of the present invention provide pre-filled adhesive pavement markers and related methods that are useful for adhering pavement markers to pavement or roadway surfaces. 
     For the purpose of this specification, the word “comprising” means “including but not limited to,” and the word “comprises” has a corresponding meaning. 
     The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.