Pointing method and apparatus

Abstract

 Pointing is applied to brickwork by means of apparatus which includes a tube (22) from which mortar or other pointing material is displaced by a piston having sealing engagement with the internal surface of the tube. The tube terminates in a tapering nose portion (23) with a centrally aligned nozzle (23a) shaped to form the mortar into a ribbon for application directly to the crevices in the brickwork.

Description

[0001] This invention relates to the application of pointing material such as mortar to brickwork and other similar structures in the process known as "pointing" in which mortar or a similar pointing material is applied to crevices between laid bricks, stones, etc., to fill such crevices either when a wall is originally constructed or subsequently by way of repair. It will be understood that such pointipg materials comprise a wet mix of generally granular matter including a cementitious binding agents.

[0002] Normally, such a pointing operation is carried out by hand using a trowel, and it is a skilled and fime-consuming process.

[0003] According to the first aspect of this invention, a method of pointing brickwork or other similar structure by the application of mortar or other similar pointing material is characterised in that the pointing material is contained within a tube having a tapering nose portion terminating in a nozzle and said material is displaced through said nozzle directly into crevices where pointing is required by means of a piston having sealing engagement with the internal surface of said tube.

[0004] Conveniently, the nozzle is shaped to afford a rectangular or square opening at its outlet end to form the displaced materiat into a ribbon of corresponding sectional shape. The piston is preferably advanced along the length of the tube by means of a manually operable plunger. The piston may incorporate a seal made of resilient material, and preferably having a concave outer face so that the seal engages the tube at positions spaced axially of the tube. Most conveniently the nozzle is aligned with the axis of the tube.

[0005] The invention also resides in apparatus for performing said method, such apparatus comprising a tube to contain a pointing material, the tube having a tapering nose portion terminating in a nozzle through which the material can be discharged, a piston having sealing engagement with the internal surface of said tube and manually operable means for advancing saitl piston along the length of said tube towards said nozzle.

[0006] The tube is preferably supported removably in a cradle so that it can be separated from the operating means for the purpose of filling with the pointing material. The operating means may be rotatable relative to the cradle about an axis coincident with that of the tube and may include a hand grip and a lever coupled to a rod on which the piston is carried.

[0007] Whilst somewhat similar types of gun are currently used for the application of mastic materials, these are not suitable for use with pointing materials due to the different natures of such materials, and whilst there have been previous proposals to apply pointing materials to brickwork mechanically, none have met with commercial success.

[0008] The pointing material used may be of generally conventional type, but may be made rather wetter than is normal for application by trowelling, and to prevent shrinkage problems on drying, the mix may include an air entraining agent which is compressed during passage of the material through the nozzle, and then expands to compensate for shrinkage as the material dries.

[0009] The invention will now be described further with reference to a preferred embodiment by way of example.

[0010] As indicated above, in accordance with the invention, a pointing operation is carried out by applying a pointing material, such as mortar, to the crevices between bricks, stones, or the like by means of a form of "gun" whereby a ribbon of such material is formed and fed directly into the crevice. This method has the advantage that the mortar can be applied more precisely, more rapidly and with less skill, than previously required. Mortar of a generally conventional type may be used, and for example, a typical mix may contain high grade Portland cement (68% to 72%), fine grade silica sand (23% to 26%), a stearate (approximately I%) and optional colouring material (up to about 6%) in a dry mixture. Water is added to this mixture to produce a settable mortar, and for the purposes of the invention it is preferred to make the mix wetter than would normally be used for manual application by trowelling-in order to assist flowability. Typically, approximately two litres of wafer would be used with 25 kilogrammes of the dry mix.

[0011] To avoid shrinkage problems, the mix preferably also includes approximately 1% of a suitable air entraining substance.

[0012] Application of the mix may be .carried out by means of the apparatus illustrated in the accompanying drawing. Such apparatus resembles a conventional mastic gun in that it incorporates a cradle structure 10 for the reception of a container 13 for the pointing material, a rod I I which extends axially of the container and carries at its forward end a piston 12 which, in use, is received within the container 13. The rod I J is adapted to be driven along the length of the container by means of a known type of manual operating mechanism 14.

[0013] Briefly, this mechanism includes a manually operable lever 15 which is pivotally mounted on an associated hand grip 15a and at its upper end bears on an apertured plate 16 which is loosely assembled on the rod I in such a manner that it can rock against an abutment 17 and thereby grip the rod to cause it to be advanced as the lever 15 is pulled towards the hand grip 15a. A return spring 18 causes the plate 16 to slide rearwardly along the rod back into contact with the abutment 17 when the lever 15 is released.

[0014] A second apertured plate 19 is provided, which reacts on an abutment 19a and acts in the opposite direction to plate 16 so as normally to prevent reverse movement of the rod 11. However, when the plate 19 is displaced manually against the action of a spring 20, the rod I can be retracted manually by means of the knob 21.

[0015] The container 13 comprises a cylindrical tube 22 having a tapering nose portion 23 of substantially conical form terminating in a nozzle 23a at the discharge end. The nozzle 23a is preferably shaped so as to afford a square or rectangular opening of appropriate dimensions so that the mortar is discharged as a ribbon of corresponding sectional shape. The container 13 is loosely assembled with the cradle 10 and therefore can be removed for the purposes of filling with an appropriate quantity of the wet mix described above, the piston 12 being fully retracted for this operation. Operation of the mechanism 14 then advances the piston 12 into the open end of the tube. The piston 12 includes a peripheral seal 24 which is located axially between two discs 25. The seal is designed to engage the interior surface of the tube and provide a fluid-tight fit. For this purpose the seal 24 is made of a suitable resilient material and preferably affords a somewhat concave peripheral outer surface 26 whereby it engages the tube 22 at two axially spaced positions and therefore acts as a double seal. Additionally, the seal 24 effectively acts as a scraper as it moves in either direction, thereby ensuring that the inner surface of the tube is maitained in a clean and smooth condition despite the nature of the mortar mix.

[0016] It is particularly important that the piston 12 should engage sealingly with the inner surface of the tube 22, partly to prevent water being squeezed out of the wet mix when pressure is applied, and draining away past the piston, and thereby altering the consistency of the mix, and partly to enable hydrostatic pressure to be applied throughout the bulk of the material to enhance flowability. Further, due to the particulate nature of the mix, it is highly desirable for the seal 24 to have a wiping action to prevent solids accumulating on the interior wall of the tube in such a manner that the seal could be locally distorted and allow water to escape.

[0017] It will be appreciated that such considerations are quite different from those which arise in the application of mastic materials by generally similar apparatus. Such mastics materials are, of course, of a generally sticky nature and tend to form a substantially coherent body, so that problems of the kind mentioned above do not arise, and it is not the practice to use a piston which engages the tube in a fluid-tight manner.

[0018] In the gun as illustrated, the cradle structure 10 includes end members 27 and 28 interconnected by three straps 29. The end member 27 carries the operating mechanism 14 preferably in such a manner that it can be rotated about an axis coincident with the rod 11. This enables the nozzle 23a to be set at an appropriate angle to suit the user and ensure that the sides of the rectangular section ribbon of mortar which is extruded through the nozzle register correctly with the edges of the crevice into which the ribbon is introduced, regardless of the angle at which the gun is held by the operator. However, it will be appreciated that in some cases the cradle might not be rotatable in order to simplify construction, and indeed instead of using a container which is loosely assembled with a cradle, it might alternatively be possible to assemble the operating mechanism directly with the open end of the container. Such an arrangement would be particularly suitable for use with containers which are supplied filled with a quantity of wet mix, ready for use.

[0019] Whilst, in the illustrated embodimeRt, the nozzle 23a and nose portion 23 are formed as part of the container 13, it would alternatively be possible for the cylinder 22 to be formed separately from the nose portion and nozzle, which could then comprise a separate assembly carried by or forming part of the cradle 10. As can be seen, the nozzle 23a is aligned with the axis of the cylinder 22 and disposed centrally relative to the conical nose portion 23. The sides of the conical nose portion preferably toper at an inclined angle relative to the axis of the cylinder which is between about 30° and 45⁰.

[0020] Further, whilst the illustrated gun is manually operated by a known mechanism, it will be appreciated that the rod I may be driven by any suitable means, whether manual or mechanised. Additionally, the container 13 may be provided with interchangeable nozzles 23 having different outlet dimensions to suit different applications, or a range of interchangeable containers may be provided, each with a different outlet nozzle. Likewise, the gun may be produced in a range of different sizes adapted for holding varying quantities of mortar.

[0021] The features disclosed in the foregoing description, or the accompanying drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

I. - A method of pointing brickwork or other similar structure by the application of mortar or other similar pointing material wherein the pointing material is contained within a tube having a tapering nose portion terminating in a nozzle and said material is displaced through said nozzle directly into crevices where pointing is required by means of a piston having sealing engagement with the internal surface of said tube.

2. A method according to claim I wherein the material is shaped by said nozzle into a rectangular or square section ribbon.

3. A method according to Claim I or Claim 2 wherein the material incorporates an air entraining substance which is compressed by passage of the material through said nozzle and subsequently expands to compensate for shrinkage as the material dries.

4. A method according to any one of Claims I to 3 wherein the nozzle is aligned with the axis of said tube.

5. A method according to any one of Claims I to 4 wherein said piston incorporates a seal made of resilient material, and having a concave outer face so that the seal engages the tube at positions spaced axially of the tube.

6. Apparatus for performing the method according to any one of the preceding claims and comprising a tube to contain a pointing material the tube- having a tapering nose portion terminating in a nozzle through which the material can be discharged, a piston having seating engagement with the internal surface of said tube and manually operable means for advancing said piston along the length of said tube towards said nozzle.

7. Apparatus according to Claim 6 wherein said manually operable means is carried by a cradle structure and said tube is releasably assembled with said cradle structure for the purpose of filling with the pointing material.

8. Apparatus according to Claim 7 wherein manually operable means is mounted on the cradle in such a manner as to enable it to be rotated relative to the cradle structure about an axis coincident with that of the tube assembled with the cradle structure.

9. Apparatus according to any one of Claims 6 to 8 wherein said manually operable means includes a hand grip and a lever coupled to a rod on which said piston is carried.

10. Apparatus according to any one of Claims 6 to 9 wherein said piston .incorporates a seal made of resilient material and is shaped to afford a concave annular outer face which engages the tube at positions spaced axially thereof.

Drawing