GB2618102A

GB2618102A - Control joint for between tiles, coatings and concrete finishes

Info

Publication number: GB2618102A
Application number: GB2206091.7A
Authority: GB
Inventors: Devlin Seamus; Devlin Tracey
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-04-27
Filing date: 2022-04-27
Publication date: 2023-11-01
Also published as: GB202206091D0

Abstract

A movement control joint in the form of a resilient strip with a flexible central portion 50 for location between to sections of finish layer. Two flexible flanges 51 either side of the central portion for location underneath the finish layer sections. The faces of the flanges may be fluted 52/53 and the edges of the flanges may be tapered to a slope 54. Also claimed is a control joint (Figure 17) comprising two bulbous parts 128 which taper towards a base of the central portion and form two pointed members 124. The joint may be made from a single elastomeric material with a cured hardness of 20 Shore A and 60 Shore A.

Description

Contro Joint for between tiles coatings ard concrete finishes tEr.j--INicAt ia The present invention relates to a movement control joint for use with tiles, coatings and concrete finishes.

BACKGRL, N D TO THE NVENTION Buildings generally employ wet components such as concrete and mortar in their construction and, as these materials dry over time, the components shrink and this can cause surface cracking of both the component and any finishes applied to it.

Buildings are subjected to expansion and contraction forces arising from thermal gain and loss by construction components. Thermal gains and losses can arise from external factors such as winter/summer and day/night cycling or from imposed heating and/or cooling from underfloor heating and cooling systems. Other factors such as wind loading, settlement and service loads all conspire to expose the structure to a rather complex, stochastic, often three-dimensional movement pattern of overlapping shear and extension/compression movements.

Similarly, changes in building technology have had a significant impact upon the design of products used to accommodate structural deflection. Multi-storey buildings use suspended slabs which are not in direct contact with the ground but instead are supported by walls or columns and beams and there is a dramatic increase in the use of composite suspended slabs.

All suspended slabs suffer from structural creep where creep is defined as the deformation of the slab under sustained load arising from gravitational loading. Creep is progressive over time where the slab sinks in the middle of its span generating compressive forces at this point which are matched with tensile rotational forces over walls and beams.

To cater for these movements it is common practice to leave a gap between substrates and any finishes applied to walls and floors. Gaps between finishes need to be filled with a flexible material which will accommodate deflections. These gaps are commonly referred to as movement joints or control joints.

Control joint gaps have to be sealed afterwards to prevent the ingress of water and other contaminants and the materials used to seal them must be flexible enough to open and close in response to the contraction and expansion of buildings components. Sealants and factory-formed jointing systems comprising rigid side members affixed to a flexible core are often used to fill control joint gaps.

Fig. 1 illustrates a cross-section of a control joint gap 6 filled with sealant 5 installed between two finishes such as tiles or other finishing media 1 said paving media being bonded to an underlying substrate 3 by means of an adhesive layer 2. The substrate 3 is generally formed with the control gap 6 by being deliberately discontinued, produced by a former which is inserted while the substrate is still plastic or sawn. This control gap 6 acts as to stress-relieve the substrate 3 during the process of drying shrinkage of said substrate such that the substrate cracks at the weakest point. I.e. at the control gap.

When sealants are used a foam termed a backer rod 4 is generally inserted into the formed control gap to the depth required to meet the width to depth ratio required by the proposed sealant to meet that products Movement Accommodation Factor and match the anticipated opening and closing movements of the control gap.

Fig. 2 displays the cross-section of a control joint gap filled with a factory-formed jointing system, a known device termed a movement joint or control joint comprising a central flexible core 30 to which L-shaped side plates 24 are bonded, co-extruded or mechanically fixed. This type of joint is representative of current control joint technology wherein the footplates are perforated with holes 26 and the control joint is embedded in an adhesive or mortar bed 22. The adhesive or mortar bed 22 lies both below and above the footplates 24 while passing through the perforated holes 26 and providing a fixative for the finishes 32. Gaps between the edges of the finishes 32 and the L-shaped side plates 24 are typically filled with a cementitious or other material generally termed grout 23. The movement control joint and the mortar bed overlie the concrete slab or similar substrate 20.

Both sealants and currently manufactured factory-formed jointing systems present problems. With regard to sealants such problems include: 1. Installation costs and on-site problems where: a. Control joint gaps must be thoroughly cleaned all surface contaminants removed. In many instances the use of a primer is necessary to ensure that the sealant successfully adheres to the substrate or finishes either side of the control joint gap. This is a time consuming and laborious process and, if not properly conducted can result in loss of adhesion between the sealant and the abutting substrate and finishes to which it must adhere to function as required. Improper surface preparation will result in adhesion failure.

b. Applying sealants in wet or frosty surfaces will cause sealant failure therefore they must be installed when substrates are dry and at the correct temperature for both adhesion and subsequent cure.

c. Generally when sealants are being applied, protection tape has to be applied to surfaces either side of the control joint gap to prevent overspill of the sealant onto the substrate or finishes either side of the control joint gap.

d. The control joint gap has to be partially filled with a foam backer rod creating a void of the correct depth and width for the sealant to meet a sealant manufacturer's specified Movement Accommodation Factor (MAF). The movement capacity of most sealants is defined in terms the percentage of the control gap width that the sealant will open and close which in turn is based upon the width and depth of the sealant seam formed on site.

The sealant can only adhere to the two opposing faces of the movement control gap and not to other surfaces as this would inhibit the sealant's capacity to extend and contract.

As a consequence, a foam based backer rod is installed within the gap to create the correct width to depth ratio required by the specified sealant said foam generally being manufactured from polyethylene to which sealant normally doesn't adhere.

The process of consistently installing the foam backer on site to the correct depth to match the requirement of the sealant being used is fraught with difficulty.

2. At the time of installation, sealants are uncured and only cure by reacting with atmospheric moisture or by using chemical additives to accelerate curing. The delayed curing process can cause problems particularly in instances where the abutting substrates move during the sealant curing process.

Joint movement during cure can cause unsightly aesthetics due to joint wrinkling, and in some severe cases, cohesive failure of the sealant. Premature adhesion loss can also occur because the adhesive characteristics of the sealant are obtained after the sealant has cured.

3. Wrong sealant selection can and will lead to many sealant failures such as using: a. Low performance sealants in high movement joints b. Silicone sealant if surface is to be painted c. Butyl sealants on wide precast panel joints d. Urethane sealants on structural glazing e. Sealants in underwater applications f. Solvent based sealants to certain paints, plastics and foams g. Silicone sealants to marble and natural stone which cause staining h. Urethane or acrylic sealants in external applications which may result in U.V. breakdown i. Sealants with incompatible materials. Sealants may react with materials that are deemed to be incompatible with that sealant. Such incompatible applications include applying: i. Acetoxy silicone to copper ii. Latex to hare steel iii. All silicones to neoprene rubber iv. Acetoxy silicone to most insulating glass sealants v. Solvent based sealants to plastic and rubber J. Poor weather and/or low U.V. resistant sealants used in exposed locations k. Sealants are affected by atmospheric and mechanical stresses, particularly where they are used externally.

The report produced by Lund Institute of Technology entitled 'The Durability and Ageing of Sealants' by Per Gunnar Burstrom studies the impact upon various sealants subjected to atmospheric and movement stresses over time found that sealant ageing depends upon a combination of factors including temperature, humidity, UV, ozone allied with chemical and mechanical stresses caused by tensile and compressive forces as control joint gaps open and close as a result of structural deflections.

Sealant that has reached its maximum service life and has become dry, brittle, cracked and/or crazed and shows sign of significant aging and should be replaced to prevent the ingress of water and other contaminants. Consequently the use of sealants in control joint gaps becomes an ongoing maintenance and replacement issue with consequent costs.

4 Sealants fail to protect the edges of brittle floor finishes such as ceramic tiles, natural stone paving and in instances where concrete (with or without thin coatings) is used as a trafficable wearing surface. By their nature sealants are highly flexible and as such offer little support to the brittle edges of materials used in floors. This lack of support can result in damage to the edges of such brittle materials which is often termed chittering'.

The results of the problems detailed above are illustrated in Figs 3,4, Sand 6 where: A. Loss of adhesion is failure of the sealant to adhere along the bond line of the surface to which it is attached, causing it to break away as shown as 6 in Fig. 3. Possible causes are joint movement exceeding the sealant capability, improper surface preparation, or improper bead configuration.

B. Fig. 4 illustrates cohesive failure 7 which occurs when the sealant fails to hold together. Cohesive failure can take the form of splits and tears in both transverse and longitudinal directions. Usual causes include improper sealant selection, poor mixing of multi-component sealants, possible air entrapment in the sealant from mixing, or improper bead configuration.

C. Substrate failure is not a failure of the sealant itself, but of the surface of the substrate to which it is supposed to adhere as shown at Sin Fig. 5. Substrate failure results from improper surface preparation. The weak interface depicted here should have been saw cut back to prevent loose pieces of the surface material from breaking away from the joint interface.

D. Fig. 6 illustrates the damage 9 that brittle finishes may experience due the lack of edge support offered by sealants.

As noted earlier and illustrated in Fig. 2, factory-formed jointing systems installed between tiles and/or other coatings and finishes and comprising rigid side members affixed to a flexible core are often used to fill control joint gaps. The main problems using sealant in control joint gaps have been detailed above. The use of factory-formed jointing systems present a differing set of problems and severe limitations in that, unlike sealants and caulking they require mechanical connection to the substrate to function. This connection is normally formed through the attachment of a central flexible material 25 to preferentially rigid side members or flanges 24 which are then keyed into an adhesive or a bedding mortar as shown in greater detail in Figs. 7 and S. Figs. 7 and 8 respectively show plan and sectional views of the device shown in Fig. 2 with rigid L-shaped side members 24 and a flexible core 25 wherein the perforations 26 in the L-shaped side plates 24 can be clearly seen. These perforations serve to locate the joint within the adhesive or mortar layer 22 and permit the adhesive or mortar layers on top and below the foot plates to cross-link with the intention of facilitating a bond between finishes 21 and the underlying substrate and holding the control joint in place.

Factory-formed joints are the source of a number of failure mechanisms which can cause damage to both finishes zones, materials and underlying substrates.

The problems arising from the use of factory formed jointing comprising rigid side members affixed to a flexible core include: 1. Failure to open in response to control gaps opening due to drying shrinkage, thermal loss and creep Control joints must respond to both the opening and closing of control gaps formed between finishes and underlying substrates and from Fig. 2 it can be seen that the generally rigid footplate members 24 and 37 are designed to stretch and compress the central flexible material 30 of the joint system, said flexible material generally being manufactured from thermoplastic plastics such as Polyvinylchloride and Polyurethane or synthetic rubbers such as Polychloroprene, Ethylene Propylene Diene Monomer, Santoprene and Silicone.

The integrity of the bond between the rigid members 24 and 37 and the adhesive or mortar bed 22 has a direct influence on the performance of the factory-formed joint in that the adhesive or mortar bed 22 must be strong enough grip the rigid members such that they stretch the flexible portion 30 of the joint and open it when building elements begin to contract through drying shrinkage, thermal loss and expansive rotational movement over beams.

The tensile strength of most cementitious adhesives and mortars varies between 0.5N/rnm2 and 1.0N/rnm2 and rarely exceeds 2.5N/mm2. As a consequence the tensile strength of the flexible section of factory-formed joints must be significantly less than this value otherwise the mechanical bond between cementitious adhesive/mortar and the factory-formed joint will fail. Table 1 below shows a list of the most common materials used to form the flexible portion of a factory-formed control joint.

Table 1: Common Materials used as the Flexible Component of a Movement Joint Material Type Minimum Tensile Strength Nimm2 Polyvinylchloride (PVC) Flexible extruded 6.9 Polyurethane Flexible extruded 5.8 Polychloroprene (Neoprene) Flexible extruded 10.2 Ethylene Propylene Diene Monomer (EPDM) Flexible extruded 9.4 Santoprene Flexible extruded 8.8 Silicone Flexible extruded 6.2 As can be seen the minimum tensile strength of these materials is significantly greater than the maximum tensile strength of the adhesive and mortar used to mechanically fix these movement joints in place. The result is that, when building elements begin to contract through drying shrinkage, thermal loss and expansive rotational movement over beams the bond between the adhesive, mortar and factory-formed joint will fail before the joint can open to accommodate the movement. The factory-formed joint will fail to open under tensile strain resulting in the delamination of the rigid side members from the adhesive or mortar as shown in Fig. 9, thus compromising the seal and allowing the passage of water and other contaminants into the gap or saw cut.

Adhesion is also compromised due to the fact that the footplates of factory formed jointing systems are manufactured from either rigid plastic or metal and present a flat and often polished surface finish to which adhesives find difficulty in adhering. Similarly, the introduction of such footplates effectively reduces the area of direct adhesive contact between the tile and substrate. It is not normal practice in the construction industry to use cementitious adhesives to form a bond with materials such as metals and plastics It is the norm to use 2-part epoxies or 2-part polyurethane adhesives to bond metals and plastics to concrete substrates. Research published in 2011 by Kurz et al 'Evaluation of adhesive bonding between steel and concrete' in Composite Construction in Steel and Concrete Volume 6: pp 669 -679 serves to underline this convention. Most adhesives used to bond paving media to substrates are cementitious, and such materials do not form a high strength, high integrity bond the metals and plastics used to manufacture the footplates of factory-formed joint systems. This means that the bond between the adhesive layer and joint footplates is low strength which can aid delamination of paving media.

To compensate for adhesion problems the footplates of the factory-formed joint are often perforated to allow adhesion between the adhesive layer beneath the footplate and the layer applied above the footplates as shown in Figs 2,7 and 8. Whilst this seemingly presents a solution to the adhesion problem it creates problems when the control gap opens up under drying shrinkage or thermal variation when the substrate contracts. When combined with the resistance to opening of the flexible core of factory-formed control joints, perforations in the flat, thin, rigid footplates slice into the adhesive layer effectively delaminating the tile or other finishes media from the underlying substrate.

Fig. 9 shows an enlarged view of a portion of the control joint shown in Fig. 8. In this instance the substrate 20 has contracted due to either thermal loss, drying shrinkage or creep, the control gap 47 has opened in response. As the substrate 20 contracts it begins to apply tensile stress via the adhesive or mortar bed 22 to the L-shaped side plates 24 of the joint. As may be seen below the tensile strength of the adhesive or mortar bed is generally insufficient to stretch the flexible core 25 of the control joint with the result that the seam of grout 23 begins to exhibit a fracture line 43. This fracture line 43 often progresses until one of the L-shaped plates 24 of the control joint is completely delaminated from the adhesive or mortar layer 22. The delamination of the control joint from the adhesive bed also has implications for the finishes 32 lying above the control joint foot plate in that said delamination means that these finishes are no longer fully bonded to the substrate 20 by means of the adhesive 22. In such cases traffic moving over the finishes in these areas sometimes cause cracking 44 in the finishes where the cracks run parallel to and contiguous with the end of the control joint footplate 28. As previously described, holes 27 are provided in the footplate.

In summary, the combination of flat, rigid and often polished plastic or metal footplates (whether perforated or not), the resistance of the central flexible core of said factory-formed control joints to opening when under tension allied with the widespread use of cementitious adhesives in the tiling industry and the associated reduction in adhesive area can cause tiling units to delaminate from the substrate resulting in the finishes cracking when subjected to traffic and other loads. This is aggravated by the fact that the outer edges of the L-shaped side members of the joint system act as a cutting edge beneath finishes.

2. Problems at intersections Unlike sealants and caulk, factory-formed control joints are supplied in fixed lengths of typically 2.0 to 2.5 metres. This means that where joint lengths are butted together (forming a linear intersection) a gap exists between joint segments which can allow the passage of water and other contaminants into the substrate underlying the tiling or resin finishes.

Similarly, the formation of intersections such as T-sections, L-sections and X-sections creates difficulties for installers where either purpose-made intersections have to be provided or the outer rigid sections of the factory-formed control joint have to be cut and installed on site. Where these steps are taken they adds cost and delay to installation. However, in many instances are factory formed control joints are laid continuously inhibiting the movement capacity of the system in transverse planes.

3. Problems caused when tiling and other finishes are not laid in a straight line As factory-formed control joints are manufactured with rigid metal or plastic side members affixed or co-extruded with a flexible central core they cannot easily be shaped or formed to accommodate curved and radiused sections of tiling or coatings which are often required to match isolation joints around columns. Similarly, designers often introduce curved and radiused designs into floor and wall tiling and coatings for aesthetic purposes.

4. Problems with the visual impact of factory-formed control joints in finishes.

Aesthetic problems are exacerbated by the width of factory-formed control joints installed in floors and walls. The width of a control gap filled with sealant is determined by the anticipated movement and the movement accommodation factor of the selected sealant. Factory-formed control joints comprise rigid metal or plastic side members affixed or co-extruded with a flexible central core wherein only the flexible core has the capacity to move. As a result, factory-formed control joints are generally significantly wider than control gaps filled with sealant and as a result often has a deleterious effect upon the designed and desired aesthetics of tiled or coated floors and walls where the exposed surface is crisscrossed with the visible lines of control joints.

5. Increased cost implications of factory-formed control joints The addition of plastic and particularly metal side plates to factory-formed control joints also has implications for cost in both manufacture and shipping. These side plates add to the cost of manufacture, add to product weight thereby incurring additional shipping costs and, as they are rigid, these products cannot be coiled and packed in smaller, lower cost and more cost-effective packs for shipping.

6. Factory-formed joints must be manufactured in differing depths to suit the combined depth of adhesive layer and finishes.

Factory-formed control joints also present a major drawback when compared to sealants in that unlike sealants, differing depths of factory-formed control joints have to be manufactured to accommodate differing tile and adhesive bed depths.

As it is necessary to incorporate footplates or flanges within the design of factory-formed joints to ensure engagement within adhesive beds, differing bed and finishes depths mean that a range of differing depth factory formed joints have to be produced to accommodate differing depth configurations. As sealants use adhesion rather than flanges or footplates they are regarded as more universally applicable. An installer of differing depths of adhesive bed and tile or other finishes often has to purchase differing depths of factory formed joints to complete a project.

As shall be seen one form of the proposed device eliminates this depth drawback wherein one depth pf the proposed factory-formed joint can be installed between finishes irrespective of the depths of adhesive and finishes being employed.

There are only two designs of factory-formed control joint known to the inventors which will open up in response to movement and which is not mechanically fixed by bonding. These are disclosed in US Patent Number 6,574,933 'Movement Joint' and UK Patent No: GB 2562793 entitled 'Improved movement joint for between tiles and coatings'. These joints comprise a compressible filler held within a rigid envelope which is compressed and installed into a preformed gap or saw cut of predetermined width and depth. As the joint is pre-compressed it will open up when the substrates either side of it shrink due to drying and thermal contraction. Both patented products comprise major limitations in that: 1. The devices proposed in both patents are designed to be installed within a slot of predefined width formed between tiled and other finishes. Variations in slot width compromise the ability of both devices to accommodate movement from the structure.

2. The proposed devices are required to be installed after finishes have been laid rather than during the process of laying finishes as disclosed in the device in accordance with the present teachings, which is designed to be installed during the tile or coating installation process.

3. The device described in US Patent Number 6,574,933 is designed to be inserted through the finishes and embedded in the substrate beneath. In many instances there isn't a gap in the substrate particularly where finishes are applied directly onto composite slabs as metal reinforcement in such slabs often lie close to the slab surface and sawing of the composite slab is not advisable.

4. The device described in US Patent Number 6,574,933 is only suitable for narrow gaps less than 5mm wide. When used in gaps wider than Smm the flexible core material protrudes beyond the joint surface when the joint comes under compression as the surrounding substrates expand due to thermal gain. This is a limitation in the use of this type of factory formed joint as the ejection of the flexible material under compression can cause a trip hazard if joints wider than Smm are used in floors The teachings disclosed herein offer improved devices which address the problems presented by both sealants and factory-formed jointing systems as disclosed above.

SUMMARY OF THE INVENT:ON

The present teachings relate to a movement control joint in the form of a resilient, elongate strip, the strip comprising a flexible central portion configured for placement between two sections of a finish layer, and flexible flanges extending from a base of the central portion, the flanges configured to extend under the two sections of the finish layer.

The flanges may have an upper and lower face and at least one of the faces is fluted. The flanges may comprise at least one of perforations and holes.

Optionally, the ends of the flanges are tapered to have outwardly sloping edges. The central portion may comprises an elongate cavity that runs through the strip.

Optionally, the central portion includes elongate outer bulbous members extending in the same direction as the flanges, the bulbous members configured to compress inwards under lateral compression of the central portion.

The central portion may have an elongate recess therein extending from the base of the central portion towards the elongate cavity.

The central portion may have a concave upper surface configured to extend upwards under lateral compression of the central portion.

The central portion may be solid.

The central portion and the flanges may be made of the same elastomeric material.

The elastomeric material is an elastomeric compound with a cured hardness of between 20 Shore A and 60 Shore A. The present teachings also relate to a movement control joint in the form of a resilient, elongate strip, the strip comprising a flexible central portion configured for placement between two sections of a finish layer, and outer bulbous parts configured to compress inwards under lateral compression from the two sections, wherein bottom of the outward bulbous parts taper towards a base of the central portion and form two pointed members.

The the two pointed members may be separated by a central recess.

The two pointed members may each include a notch portion for engagement in an adhesive layer beneath the finish layer.

The central portion may comprise an elongate cavity that runs through the strip.

The joint may be composed of an elastomeric material.

The elastomeric material may be a flexible elastomeric compound with a cured hardness of between 20 Shore A and 60 Shore A. BRIEF DESCR [ION OF THE DRAWINGS Embodiments of the device will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 illustrates a cross-section of a control joint gap filled with sealant installed between two finishes such as tiles or other finishing media said paving media being bonded to an underlying substrate by means of an adhesive layer; Fig. 2 shows an isometric sketch of a typical known factory-formed movement joint designed to be installed between finishes; Fig. 3 shows where a seam of sealant or caulking loses adhesion along the bond line of the surface to which it is attached, causing it to break away; Fig. 4 illustrates cohesive failure of a sealant which occurs when the sealant fails to hold together wherein such cohesive failure can take the form of splits and tears in both transverse and longitudinal directions; Fig. 5 illustrates substrate failure which is not a failure of the sealant itself, but rather of the surface or substrate to which it is supposed to adhere; Fig. 6 illustrates the damage that brittle finishes may experience due the lack of edge support offered by sealants and caulking; Fig. 7 shows a plan view of the factory-formed control joint detail shown in Fig. 2; Fig. 8 shows a sectional view of the factory-formed control joint detail shown in Fig. 2; Fig. 9 shows a sectional view of the factory-formed control joint shown in Figs. 2,7 and 8 after the substrate has contracted through either drying shrinkage, thermal loss or expansive rotational movement due to creep and the associated failure mechanisms of currently manufactured factory-formed control joints; Fig. 10 presents a sectional view of the device in accordance with the present teachings comprising a solid flexible extrusion manufactured from an elastomeric material having a central portion without cavities with side flanges of the same flexible elastomeric material; Fig. 11 shows an isometric view of one of the flanges of Fig. 10 which are fluted to increase the surface area in contact with the adhesive used to affix the device in position as well as a fluted surface used to increase adhesion between the device, the adhesive being used and the finished being applied on top of this adhesive layer. Similarly it shows perforations or holes in the flanges which aids the bond of the upper layer of adhesive to the adhesive layer underlying the device; Fig. 12 presents an alternate sectional view of the device in accordance with the present teachings comprising a flexible extrusion manufactured from an elastomeric material having a central portion with a cavity or void with side flanges of the same flexible elastomeric material; Fig. 13 shows another alternate sectional view of the device in accordance with the present teachings comprising a flexible extrusion manufactured from an elastomeric material having a central portion with a cavity or void wherein the side flanges have been omitted; Fig. 14 shows the device illustrated in Fig. 10 installed on an adhesive bed with abutting tile or other finishes; Fig. 15 displays the process of installation of the device noted in Fig 12 wherein the device has been laid on an adhesive bed and a tile or other finish has been installed on one side of the device; Fig. 16 shows the device illustrated in Figs. 12 and 15 fully installed between two tiles or other finishes wherein during the installation of the second tile, and whilst the adhesive layer is still plastic, the device has been pre-compressed by the lateral motion described as moderate compressive force normally used to ensure engagement of the tile in the adhesive and to eliminate any air pockets at the finish/adhesive/substrate interface; Fig. 17 illustrates the first part of installation of the device shown in Fig 13 wherein tiles or other finishes have been laid on an adhesive bed one side of a control gap and the device is placed abutting the installed tile; Fig. 18 shows the device of Fig. 13 fully installed between two tiles or other finishes wherein during the installation of the second tile, and whilst the adhesive layer is still plastic, the device has been pre-compressed by the lateral motion described as moderate compressive force normally used by those experienced in the art to ensure engagement of the tile in the adhesive and to eliminate any air pockets at the finish/adhesive/substrate interface; Fig. 19 illustrates the installation of the device shown in Fig 13 wherein tiles or other finishes have already been laid on an adhesive bed leaving a control gap between these tiles into which the device is being inserted; and Fig. 20 shown the device detailed in Figs. 13 and 19 once the device has been compressed and fitted into a control gap formed between tiles.

iDE-1558:i,-11) DESCR1PT,ON OF ygIMENTS The present teachings provide a factory-formed movement control joint in the form of a resilient extrusion for installation between tiles and coatings in the forms of: * A device with extruded flexible footplates or flanges shown in detail in Figs. 10, 12, 14, 15 and 16 said flanges being perforated to allow adhesive beneath the flange to bond with the adhesive layer above the flange. The proposed flanges area also fluted on their upper and lower faces to increase engagement with adhesives used to affix finishes.

* The device shown with the flanges shown in detail in Fig. 11 wherein these flanges extend from a flexible central core as shown in Figs. 10 and 14 wherein the central core is a solid extrusion without cavities.

* The device shown with the flanges shown in detail in Fig. 11 wherein these flanges extend from a flexible core as shown in Figs. 12, 15 and 16 wherein the central core has an internal cavity or cavities.

* A device wherein the flexible flanges have been omitted as shown in Fig 13, 17, 18, 19 and 20 said elongate strip having an internal cavity or cavities which allows the device to be inserted into a control joint gap pre-formed between finishes after said finishes have been laid.

The devices in accordance with the present teachings share common characteristics and forms in that: 1. They are designed to be installed between finishes and during that process are pre-compressed to prime opening movement as the control gap opens up due to drying shrinkage of substantially wet substrates and contraction of substrates and finishes due to thermal loss.

2. They comprise a single extrusion of a flexible elastomeric material comprising diene, non-diene, and/or thermoplastic elastomers potentially but not limited to polymers such as alkyl acrylate copolymer, polybutadiene, butyl, ethylene propylene diene comonomer, hydrogenated nitrile, chloroprene, silicone, polyurethane and polyester amide.

3. Preferentially the device shall be manufactured from a flexible elastomeric compound with a cured hardness of between 20 Shore A and 60 Shore A 4. During the installation of finishes compressive force is normally used by those experienced in the art to ensure that the finishing media is securely located within the fixing media where this media is either an adhesive or a mortar bed. Finishes are pressed into the adhesive or mortar substrate to ensure engagement between the substrate, the adhesive or mortar layer and the finishes. At the same time force is applied to the finishes in a lateral motion to further ensure engagement and to eliminate any air pockets at the finish/adhesive/substrate interface. It is this lateral motion which is described herein as moderate compressive force whereby pressing the finish against the device causes it to compress and be retained in this position by the mass of the finishes and the strength of the adhesive. The Shore A hardness of the flexible material from which the device is manufactured can be thereby varied to meet the combined requirements of both the type and mass of finishes being applied and the tensile and bonding strength of the bonding media employed.

5. The sole visible difference between the devices shown in Figs. 10, 12, 14, 15 and 16 and those shown in Figs. 13, 17, 18, 19 and 20 lie principally in the method of installation wherein the devices shown in Figs. 10, 12, 14, 15 and 16 have flanges that extend into the adhesive which is used to affix finishes to underlying substrates whereas the device shown in Figs. 13, 17, 18, 19 and 20 do not have flanges and is either installed in a gap previously formed between finishes or if being installed whilst finishes are being laid is located and compressed between finishes as part of the normal process of finishes installation.

6. This modified design of the device shown in Figs. 13, 17, 18, 19 and 20 also presents a major improvement in the current design of factory-formed joints in that it eliminates the problem of finishes installers having to source differing joint depths for differing adhesive and tile depth combinations. The absence of flanges mean that the device can be used with tiles or other finishes of differing depth laid on differing adhesive bed depths Hence, an installer of differing depths of adhesive bed and tile or other finishes no longer has to purchase differing depths of factory formed joints to complete a project.

The device having extruded flexible footplates shown as flanges extending from a flexible core without voids or cavities and displayed as Fig. 10 comprises a flexible central core 50 from the base of which flanges 51 extend outwards said flanges having flutings 52, 53 on their upper and lower faces and having outward sloping edges 54. This design step is taken to counter the problem of finishes cracking due to problems in the design of current factory-formed control joints which employ flat rigid or plastic footplates. Specifically, the design of the end of the rigid side members of the factory-formed joint can exacerbate cracking where generally they comprise a 90 degree angle as shown at 28 of Fig. 9 wherein this acts as an edge upon which unbonded finishes bear and subsequently fail by cracking 44. By having outward sloping edges 54 at the end of flanges shown in Fig. 10 this problem is eliminated.

As the device is designed to be entrapped within the finishes/adhesive/substrate interface, flutings 52 and 53 of the flanges increases the device's engagement and coefficient of friction when it comes under tension during the drying shrinkage and thermal loss experienced by finishes and substrates.

Fig 11 shows the flanges described in Fig. 10 in greater detail illustrating longitudinal flutes 60 in the upper surface of the flange and similar fluting 61 in the lower face of the flange wherein said fluting is designed to form a greater contact area for the adhesive used to bond the device and finishes to adhere. Fig. 11 also shows the sloping outer edge of the flange 62 and perforations or hole 63 in the flange 62 designed to allow direct contact between adhesive spread beneath the flange with that placed on top of the flange ensuring a high integrity bond firmly fixing the device and any applied finishes in place.

Fig. 12 displays a variation of the device wherein the flexible central core 70 has been extruded with an oval or ovoid cavity 71. For simplicity Fig 12 displays only one form of the device with a single cavity 71 though it should be noted that other forms incorporating multiple voids within the central flexible core are considered to lie within the scope of the present teachings.

Fig 12 shows a flexible central core 70 from the base of which flanges 72 extend outwards said flanges being fluted on their upper and lower faces being as shown and described in greater detail in Fig 11. Fig 12 presents a design with outer members of the device having outer bulbous parts 73 which are designed to compress inwards during installation of finishes such as tiles, coatings and other finishing media. The core 70 also includes a central recess 74 extending from the base of the device towards the cavity 71.

Fig. 13 presents a form of the device 80 wherein the flexible flanges described in Fig. 11 have been omitted wherein said elongate strip having an internal cavity oval or ovoid cavity 81 or cavities which allows the device to be inserted between finishes either as said finishes are being installed or into a control joint gap pre-formed between finishes after said finishes have been laid. The device has a concave upper surface 84.

This variation of the proposed device has been designed to eliminate the problem where the installers of finishes have to source differing depths of factory-formed joint to meet differing adhesive and finishes depth configurations. By eliminating the flanges this problem is eradicated.

Fig 13 presents a design with outer members of the device having outer bulbous parts 82 which are designed to compress inwards during installation of finishes such as tiles, coatings and other finishing media.

The device shown in Fig. 13 tapers inward from the bottom of the outward bulbous parts 82 to form two separate dart-shape members 83 separated by a central recess 85 thereby forming a substantially V-shaped device. A lower section 87 of the device 80 is provided between the cavity 81 and the recess 85. This design element has been included to aid the progressive insertion of the device into a control joint gap pre-formed between finishes after said finishes have been laid wherein the recess 85 has the ability to close if required during insertion of the device. Similarly, these dart-shapes 83 and the notches 86 allow the device to engage and become fixed in place within the underlying adhesive layer.

Fig. 14 shows the device earlier illustrated in Fig. 10 installed above a control gap 95 formed between two sections of substrate 90 and the device fitted within an adhesive layer 93 on top of which finishes 94 have been applied either side. The flanges 92 of the device extend outwards from the central portion 91 of the device and are embedded in the adhesive layer 93 such that adhesive lies both below 97 and above 96 said flanges and engaging within the flutings on both surfaces of the flanges thereby increasing the engagement of the device within the adhesive layer. The flanges 92 are provided with outward sloping edges 98 as previously described.

Fig. 15 shows the first steps in the installation of the device displayed in Fig. 12. The flanges of device are installed within an adhesive layer 101 directly above a control gap 100 formed in the underlying substrate 108 such that adhesive 101 lies both above and below the flanges 105 extending outwards from the central portion 104 of the device with the central cavity 106. The device is installed in this relaxed uncompressed state, the concave surface 107 of the device is unchanged and a layer of finishes 102 is applied one side of the proposed product such that it is securely embedded in the adhesive whilst abutting the device. As previously described the flutings 103 aid in the secure embedding.

Fig. 16 presents the second stage of installation of the device displayed in Fig. 12 (above control gap 110) where a second layer of finishes 115 is applied onto an adhesive bed 114 on the opposite side of the device 111 as previously shown in Fig. 15. Under the moderate compressive/lateral force exerted and used by those experienced in the art during the installation of this second layer of finishes, the outer sloping bulbous parts 118 of the outer members of the device compress inwards and flatten which in turn distorts the oval cavity 113 such that upper 117 and lower 119 sections of the extrusion or device are forced upwards and downwards respectively. The impact on the surface of the device is to force the previously concave surface 112 upwards to produce a generally flat upper surface between the upper edges of the outer members of the device 111. This action also causes the outer faces of the device to be inclined to press outwards against the faces of the finishes and provide reinforcement to the brittle edges of these components. Flanges 116 as previously described are also provided.

Fig. 17 presents the device 121 as shown in Fig. 13 as it is being installed as a part of the process of laying finishes. In this instance a layer of finishes 125 one side of the device 121 has been installed onto an adhesive bed 126 and the device 121 is installed abutting the finishes layer 125 and directly over the control gap 120 formed within the substrate 127. The device 121 is installed uncompressed wherein neither the oval cavity 123 within the core of the device nor the concave surface 122 of the device have been affected. The outer bulbous parts 128 are also uncompressed. Preferentially the dart shaped ends 124 of the device are pressed into the adhesive substrate 126.

Fig. 18 illustrates the second phase of the installation of the device shown in Fig. 17 wherein a second finishes layer 134 is applied onto an adhesive layer 135 which has been applied to a substrate within which a control gap 130 has been formed. The second finishes layer 134 being applied to the opposite side of the device 131 wherein a finishes layer 133 had been applied previously.

Under the moderate compressive/lateral force exerted used by those experienced in the art during the installation of finishes, the outer sloping bulbous parts 137 of the outer members of the device 131 compress inwards. The impact of this compression is seen in the distortion of the central cavity or void 136 which in turn applies upward pressure to the concave upper surface shown as 122 in Fig 17 of the invention forcing the said concave upper surface of the device upwards to produce a generally flat upper surface 132 between the upper edges of the outer members of the device as shown in Fig. 18.

The uplift force experienced by the resilient material of the invention causing the concave upper surface of the device to flatten as shown by 132 also increases the internal compression and compaction of said resilient material which further increases support to the edges of sometimes brittle finishes that may abut the device 131.

The application of the second finishes layer 134 affixed onto an adhesive layer (or bed) 135 combined with the moderate compressive/lateral and compressive force exerted upon the finishes 134 causes the adhesive layer 135 to encompass the substantially dart-shaped ends 138 of the device and to extend above these ends as shown at 139 effectively encapsulating the base of the device and securing it within the said adhesive layer 135.

Fig. 19 displays an alternate method of installing the device 141 shown as in Fig. 13. In this instance the device 141 is progressively inserted into a control joint gap 140 pre-formed between finishes 142 or sections of substrate that have already been laid wherein a control gap of predetermined width and depth has been produced between finishes and/or sections of substrate. Current international standards and norms clearly define control gap widths for differing locations and magnitudes of anticipated movement.

Fig 19 displays the first stage of the alternate device 141 being installed between finishes 142. This figure shows a control gap 145 formed between two sections of substrate 146 which has been mirrored by the formation of a control gap 140 between finishes 142. An adhesive layer 143 is provided beneath the finishes 142. Alternatively where finishes are not being applied or thin coatings are used, a control gap of appropriate width and depth can be formed between the sections of substrate to accommodate both movement of the control gap and the movement capacity of the device.

Fig. 19 displays the device 141 being inserted into the control gap 140. As the device is pressed into the control gap 140 between the finishes 142 the bulbous side members 147 of the devices are compressed inwards and the cavity or void 144 begins to distort as the device progressively enters said gap 140.

Fig. 20 shows the device 151 after it has been fully installed between finishes 153 having been compressed by action of pressing the device into the control gap left between the finishes as described in Fig. 19. The action of pressing the device into the preformed control gap slot 157 has the effect of causing the bulbous sections of flexible side members (shown as 147 in Fig 19) to be pressed inwards as seen at 159 in Fig. 20.

The impact of this compression is seen in Fig 20 in the distortion of the central void or cavity 155 of the device 151 which in turn applies upward pressure to the concave upper surface shown as 148 in Fig 19 of the invention wherein the concave upper surface of the device is forced upwards to produce a generally flat upper surface as displayed in 152 at Fig. 20 between the upper edges of the outer members of the device.

The uplift force experienced by the resilient material of the invention causing the concave upper surface of the device to flatten as shown as 152 in Fig. 20 also increases the internal compression and compaction of said resilient material which further increases support to the edges of sometimes brittle finishes 153 that may abut the device 151. This figure shows a control gap 150 formed between two sections of finish 153 which has been mirrored by the formation of a control gap 157 between finishes 153. An adhesive layer 154 is provided beneath the finish layer 153. As previously described, the device is provided with tapered or pointed ends 158 for insertion in the adhesive layer 154. Central recess 156 narrows under lateral compression caused the two section of finish layer.

It can be seen that the present teachings provide a factory-formed movement joint designed to fill control joint gaps between finishes to allow for differential movement of these components. It has also been designed to eliminate the problems noted above with both sealants and currently manufactured factory-formed control joints. It has been designed specifically to: a. Reduce installation costs and on-site installation problems associated with sealants b. Eliminate problems associated with uncured sealants being applied between finishes including the wrong sealants being selected, the impact of poor weather and UV degradation during and following sealant installation and cure.

c. Replace traditional sealants with a fully cured alternative thereby eliminating the impact of atmospheric and mechanical stresses upon sealants leading to failure.

d. Replace sealants with a device that supports and protects the edges of brittle finishes such as tiles and concrete surfaces.

e. In one form to overcome the depth problem of factory-formed control joints wherein differing depths of factory-formed control joints currently have to be manufactured and sourced by installers of finishes to accommodate differing finishes and adhesive bed depths.

f. Eliminate problems encountered by installers of finishes wherein previously they had to source specific depths of factory-formed joints depending upon the depth of finishes and adhesive materials being employed.

g. Eliminate the failure of factory-formed joints to open in response to drying shrinkage, thermal loss and creep.

h. Eliminate the delamination of both factory-formed control joints and abutting tiles wherein under the tension arising during drying shrinkage the thin, rigid footplates of presently manufactured factory-formed control joints slice into the adhesive layer which is used to affix and secure both control joints and tiles in position. Solving this problem similarly solves issues of tile cracking.

i. Be formed on site to accommodate differing tiling patterns such as curves in differing planes.

j. Reduce the visual impact and cost of factory-formed control joints.

The device in accordance with the present teachings is configured to open to compensate for the drying shrinkage, thermal contraction and expansive rotational stresses in building slabs at the mid-point of beams supporting said slabs.

Similarly the device will close in response to expansion of buildings elements due to thermal gain, wind loading and the compression forces arising at the mid-point of slab spans.

The control joint has been designed to be produced in a controlled environment in a factory so as to eliminate the negative impact of workmanship and site conditions which regularly affect the installation and performance of sealants and caulking which are also used for this type of application.

One improvement of the device in accordance with the present teachings is that it is fully cured before it is installed and doesn't suffer from the cure or width to depth ratio problems often associated with the application of caulk and sealants.

Unlike sealants, the present invention will preferably be substantially manufactured from plastic elastomeric polymers the aging characteristics of which are well understood. More than 2,000 accelerated aging testing protocols have been accepted by the American Society for Testing and Materials (ASTM) and, depending on product application, the polymer employed will be matched to the environment to maximise service life.

Unlike sealants and caulk the device in accordance with the present teachings is not subject to 'slump'. Therefore the width of the gap is not a limiting factor in the design of the proposed device as there are few limitations beyond the extrusion width limits of existing thermoplastic and synthetic rubber extrusion technology. Similarly the movement capacity of the invention is only limited by existing extrusion technology.

Preferably the device has been designed to prevent the ingress of debris, water and other contaminants throughout both opening and closing movement cycles.

Another advantage of the present teachings is that it provides a device which is trafficable by pedestrians and vehicles and resists penetration and damage by such traffic.

Similarly, as it is extruded and fully cured when installed unlike sealants it does not fail through loss of adhesion, cohesion and substrate failure and is not reliant upon surface preparation or site workmanship.

As the device is being installed it is compressed between finishing units and thereby offers support and prevents damage to the arris of brittle finishes such as concrete, ceramic tiles, coatings, epoxy resin finishes and natural stone by the aforementioned pedestrians and vehicles. Caulk and sealant provide little or no lateral support to the arris of the brittle finish with the result that attrition from pedestrian and wheeled traffic cause cracking and failure at the unsupported edge. This support is given by the preformed joint being held under compression throughout the movement cycle of the structure said compression acting on the flexible core which forces the upper section of said core upwards and outwards to support the edges of brittle finishes.

The invention in accordance with the present teachings is manufactured as a flexible elastomeric extrusion and is pre-compressed during installation wherein this pre-compression is released when a control gap opens. Hence, unlike standard factory-formed control joints which rely upon tension being applied to a flexible central core by means of rigid footplates embedded in an adhesive layer, this pre-compressed device does not rely upon mechanical fixation to open and thereby does not fail to open in response to control gaps opening due to drying shrinkage, thermal loss and creep.

Similarly, the combination of pre-compression during installation allied with the fact that the flanges of the device where used are manufactured from a flexible elastomeric material and are not rigid plastic or metal materials such as currently employed in the manufacture of factory-formed control joints means that significantly less shear stress is applied to the adhesive layer when the control gap opens under the forces of drying shrinkage or thermal loss. The effective elimination of the transmission of tensile forces from the installed joint into the adhesive layer reduces the problem of adhesive layer failure and consequent delamination and failure of finishes.

As noted above, unlike the design of currently manufactured factory-formed control joints that have flat thin, rigid footplates with perforations that slice into the adhesive layer effectively delaminating the tile or other finishes media from the underlying substrate, the invention in accordance with the present teachings has flexible flanges that are fluted thereby increasing the contact area between the adhesive and the device. The flanges of the proposed device are also perforated to permit the adhesive beneath the flanges to come in contact and adhere to the adhesive layer applied above said flanges. However, should the invention ever come under tension which may happen when the opening movement of the control gap is greater than anticipated, the flanges are flexible and not rigid hence they stretch and do not slice into the adhesive layer unlike the footplates of currently manufactured control joints.

As noted earlier, factory-formed joints present problems at intersections wherein such joints are typically supplied in 2.0 to 2.5 metre lengths meaning that where joint lengths are butted together (forming a linear intersection) a gap exists between joint segments which can allow the passage of water and other contaminants into the substrate underlying the tiling or resin finishes.

The device in accordance with the present teachings can be manufactured as a continuous extrusion (or strip) 50 to 100 metres long and packed in coil form meaning that there are fewer butt intersections and potential areas of failure.

Similarly, as the device is manufactured from a single flexible extrusion (or strip) it is simpler to cut on site using either scissors or a craft knife to formation intersections such as T-sections, L-sections and X-sections.

Unlike factory-formed joints with rigid footplates the flexibility of the device lends itself to being formed on site to accommodate curved and radiused sections of tiling, coatings and other finishes.

Similarly, when compared to factory-formed control joints with rigid side members the present invention has a much narrower visible surface profile width wherein rigid side members are not required. Therefore the device offers a much less deleterious impact upon the designed and desired aesthetics of tiled or coated floors and walls when compared to presently factory-formed control joints.

The addition of plastic and particularly metal side plates to factory-formed control joints has implications for cost in both manufacture and shipping. These side plates add to the cost of manufacture, add to product weight thereby incurring additional shipping costs.

As the device in accordance with the present teachings has no rigid outer frames it can be coiled and packed in smaller, lower cost and more cost-effective packs for shipping and storage.

Claims

1. A movement control joint in the form of a resilient, elongate strip, the strip comprising: a flexible central portion configured for placement between two sections of a finish layer; and flexible flanges extending from a base of the central portion, the flanges configured to extend under the two sections of the finish layer.

2. The movement control joint of claim 1, wherein the flanges have an upper and lower face and at least one of the faces is fluted.

3. The movement control joint of claim 1 or 2, wherein the flanges comprise at least one of perforations and holes.

4. The movement control joint of any one of claims 1 to 3, wherein the ends of the flanges are tapered to have outwardly sloping edges.

S. The movement control joint of any one of claims 1 to 4, wherein the central portion comprises an elongate cavity that runs through the strip.

6. The movement control joint of any one of claims 1 to 5, wherein the central portion includes elongate outer bulbous members extending in the same direction as the flanges, the bulbous members configured to compress inwards under lateral compression of the central portion.

7. The movement control joint of claim 5 or 6, wherein the central portion has an elongate recess therein extending from the base of the central portion towards the elongate cavity.

8. The movement control joint of any one of claims S to 7, wherein the central portion has a concave upper surface configured to extend upwards under lateral compression of the central portion.

9. The movement control joint of any one of claims 1 to 4, wherein the central portion is solid.

10. The movement control joint of any one of claims 1 to 9, wherein the central portion and the flanges are made of the same elastomeric material.

11. The movement control joint of claim 10 wherein the elastomeric material is an elastomeric compound with a cured hardness of between 20 Shore A and 60 Shore A.

12. A movement control joint in the form of a resilient, elongate strip, the strip comprising: a flexible central portion configured for placement between two sections of a finish layer; and outer bulbous parts configured to compress inwards under lateral compression from the two sections; wherein bottom of the outward bulbous parts taper towards a base of the central portion and form two pointed members.

13. The movement control joint of claim 12, wherein the the two pointed members are separated by a central recess.

14. The movement control joint of claim 12, wherein the the two pointed members each include a notch portion for engagement in an adhesive layer beneath the finish layer.

15. The movement control joint of any one of claims 12 to 14, wherein central portion comprises an elongate cavity that runs through the strip.

16. The movement control joint of any one of claims 12 to 15, wherein the central portion has a concave upper surface configured to extend upwards under lateral compression of the central portion.

17. The movement control joint of any one of claims 12 to 16, wherein the joint is composed of an elastomeric material.

18. The movement control joint of claim 17 wherein the elastomeric material is a flexible elastomeric compound with a cured hardness of between 20 Shore A and 60 Shore A.