Expansion Joint Assembly

Description

The present invention relates to an expansion joint assembly for location in a gap defined between first and second structural members, such as sections of a road, bridge structure, car park or a combination thereof or parts of a building or buildings, and methods for forming such a joint.

Expansion joints are typically disposed between sections of a road or at the end of a bridge structure where it joins the road and must satisfy a number of requirements. For example, they must be suitably robust to withstand the loads generated by passing vehicles whilst being sufficiently flexible to accommodate changes in the gap width between sections resulting from environmental changes such as variations in temperature.

A particular type of joint defined by the Highways Agency Standard BD33/94 is the Highways Type 6 bridge expansion joint, which is commonly referred to as an ‘Elastomer in Rail-Resin Encapsulated’ (EMR-RE) expansion joint. Current EMR-RE joints are based on essentially the same design, which is more than 30 years old. An example of an EMR-RE joint is shown in FIG. 1.

Referring to FIG. 1, there are four basic components to a conventional EMR-RE joint 1: a pair of extruded steel rails 2; steel reinforcing bars 3 bolted or welded to the rails 2; pitch or bitumen extended hot applied epoxy resin based mortar 4, which is used to hold the reinforcing bars 3 and thereby the rails 2 in place; and an elastomeric seal 5 disposed between the rails 2. Typically the rails 2 are laid down; one to each side of an expansion gap 6, with the reinforcing bars 3 extending away from the centre of the gap 6. Uncured mortar 4 is then poured into cavities defined between the outer surface 7 of each rail 2 and a surface 8 of the road or bridge sections 9 between which the joint 1 is to be formed. Once the mortar 4 has fully cured the elastomeric seal 5 is interposed between the inner surfaces 10 of the rails 2 to complete the joint 1. An example of such an EMR-RE joint is described in GB-A-2060734.

Although EMR-RE joints of the kind described above are widely used in the road/bridge construction industry, they suffer from a number of problems. For example, undesirable levels of stress can be induced between components within the joint as a result of employing components made from materials having different physical and chemical properties, such as differing thermal expansion coefficients. Moreover, a joint may lose its structural integrity due to failure of the welds or bolts connecting the reinforcing bars to the rails. Furthermore, corrosion of the rails and/or reinforcing bars due to aging or exposure to water and do-icing salts is known to be a significant factor in joint failure. Additionally, the exposed upper surface of the mortar 4 can be slippery and produce a risk of vehicles skidding as they pass over the joint 1. The current solution to this problem is to cast a skid resistant aggregate into the upper surface of the mortar 4 whilst the mortar 4 is curing. However, the bond between the skid resistant aggregate and the mortar 4 is typically unsatisfactory and often leads to the loss of skid resistance at an early stage in the lifetime of the joint 1.

An object of the present invention is to obviate or mitigate the aforementioned problems.

According to a first aspect of the present invention there is provided an expansion joint assembly for location in a gap defined between first and second structural members, the assembly comprising a sealing member and at least one anchor member, said anchor member having a first portion for connection to the sealing member and a second portion for connection to one of said structural members, wherein said first and second portions of the anchor member are integrally formed.

By integrally forming the first and second portions of the anchor member, problems related to the failure of the welds or bolts connecting the reinforcing bars to the rails of a conventional joint are overcome.

Preferably the anchor member is formed from a material comprising an organic polymer resin. It is preferred that the resin is selected from a group consisting of a polyester resin, a vinyl ester resin, a polyurethane resin, an acrylic resin and an epoxy resin.

The resin preferably contains chemical groups derived from an unsaturated organic monomer compound. The resin may contain moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester).

The material from which the anchor member is formed preferably incorporates a suitable reinforcing material, e.g. a reinforcing material selected from a group consisting of glass fibre, glass mat, steel, carbon fibre and polyparaphenyleneterephthalamide.

In a preferred embodiment of this aspect of the present invention one of the first portion of the anchor member and the sealing member defines a projection configured for receipt in a complementary slot defined in the other member.

A layer of skid resistant material may be provided on an exposed upper surface of the first portion of the anchor member. The skid resistant material may comprise an organic polymer resin, which is preferably selected from a group consisting of a polyester resin, a vinyl ester resin and an acrylic resin. The resin comprised in the skid resistant material preferably contains chemical groups derived from an unsaturated organic monomer compound and more preferably contains moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester). It is preferred that both the skid resistant material and the material from which the anchor member is formed are organic polymer resins. More preferably both the skid resistant material and the material from which the anchor member is formed are the same organic polymer resin.

Preferably the second portion of the anchor member is adapted to be connected to one of said structural members via mortar cast into the gap defined between the structural members. The mortar is preferably an organic polymer resin and is preferably selected from a group consisting of a polyester resin, a vinyl ester resin, a polyurethane resin, an acrylic resin and an epoxy resin.

The resin preferably contains chemical groups derived from an unsaturated organic monomer compound. The resin may contain moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester).

In a preferred embodiment of the first aspect of the present invention both the material from which the anchor member is formed and the mortar are organic polymer resins. More preferably both the material from which the anchor member is formed and the mortar are the same organic polymer resin. Yet more preferably, when a layer of skid resistant material is provided on an exposed upper surface of the first portion of the anchor member, the resins comprised in the anchor member, skid resistant layer and the mortar are organic polymer resins, preferably the same organic polymer resins. Forming the anchor member from a similar material to the mortar (and the skid resistant layer if present) overcomes problems resulting from employing components made from materials having different physical and chemical properties, which might otherwise result in joint failure due to undesirable levels of stress being induced between components within the joint.

A layer of skid resistant material may be provided on an exposed upper surface of the mortar cast into the gap defined between the structural members. The skid resistant material may comprise an organic polymer resin, which is preferably selected from a group consisting of a polyester resin, a vinyl ester resin and an acrylic resin. The resin comprised in the skid resistant material preferably contains chemical groups derived from an unsaturated organic monomer compound and more preferably contains moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester).

It is preferred that both the resin comprised in the skid resistant material and the mortar are organic polymer resins. More preferably both the resin comprised in the skid resistant material and the mortar are the same organic polymer resin.

It is preferred that a layer of skid resistant is material provided on both the exposed upper surface of the mortar and the first portion of the anchor member. Preferably the layers of skid resistant material provided on the exposed upper surfaces of the mortar and the first portion of the anchor member comprise the same organic polymer material.

It is preferred that the second portion of the anchor member defines a locking member configured to contact said mortar when said mortar is cast into said gap to lock said anchor member against said mortar. The locking member is ideally elongate and at least a section of it may be tapered such that its thickness at a position proximal to the first portion is less than that distal from the first portion. Moreover, a surface of the locking member that is adapted to be in contact with the mortar when the mortar is cast into said gap may be provided with surface texturing. Additionally, said locking member may define at least one aperture for receipt of mortar when said mortar is cast into said gap. The aperture may be in the form of an elongate slot.

The anchor members may be in the form of elongate rails for location in an elongate gap between the structural members.

In a preferred embodiment of the invention the assembly comprises two anchor members, one anchor member having a second portion for connection to the first structural member and the other anchor member having a second portion for connection to the second structural member.

According to a second aspect of the present invention there is provided a method for forming an expansion joint between first and second structural members comprising locating an assembly according to the first aspect of the present invention in a gap defined between said structural members; said locating of the assembly comprising connecting the first portion of the anchor member to the sealing member and connecting the second portion of the anchor member to one of the structural members.

Preferably the method comprises the step of casting a layer of a skid resistant material on an exposed upper surface of the first portion of the anchor member.

It is preferred that said connecting of the second portion of the anchor member to said one of the first and second members comprises casting mortar into said gap such that said mortar contacts the second portion of the anchor member and said one of the first and second members. Preferably a layer of a skid resistant material is cast on an exposed upper surface of the mortar cast into the gap defined between the structural members.

According to a third aspect of the present invention there is provided a method for forming an expansion joint between first and second structural members comprising locating an assembly comprised of a sealing member and at least one anchor member having first and second portions in a gap defined between said structural members; said locating of the assembly comprising connecting the first portion of the anchor member to the sealing member, placing the anchor member into said gap, and casting mortar into said gap to connect the second portion of the anchor member to one of the structural members, wherein at least a part of at least the second portion of the anchor member chemically bonds to the mortar.

In this way, the connection between the anchor member and the structural member via the mortar is significantly stronger and more uniform than that in prior art joints employing steel rails and reinforcing bars.

The anchor member is preferably formed from a material comprising an organic polymer resin containing crosslinkable moieties. Preferably the crosslinkable moieties are double bonds between adjacent carbon atoms of the polymer resin. The resin may be selected from a group consisting of a polyester resin, a vinyl ester resin and an acrylic resin. The resin preferably contains chemical groups derived from an unsaturated organic monomer compound. The resin may contain moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester).

In a preferred embodiment of this aspect of the present invention said material incorporates a suitable reinforcing material, e.g. a reinforcing material selected from a group consisting of glass fibre, glass mat, steel, carbon fibre and polyparaphenyleneterephthalamide.

Preferably the mortar comprises an organic polymer resin containing terminal crosslinkable moieties and a crosslinking agent. The resin is preferably selected from a group consisting of a polyester resin, a vinyl ester resin and an acrylic resin. The resin preferably contains chemical groups derived from an unsaturated organic monomer compound. The resin may contain moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester). In a preferred embodiment of the third aspect of the present invention both the material from which the anchor member is formed and the mortar comprise organic polymer resins containing crosslinkable moieties. More preferably both the material from which the anchor member is formed and the mortar comprise the same organic polymer resin containing crosslinkable moieties.

It is preferred that the crosslinking agent is an unsaturated organic monomer compound. The crosslinking agent may be selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester).

Furthermore, the terminal crosslinkable moieties are preferably methacrylate ester moieties.

In a further preferred embodiment of this aspect of the invention, during casting said mortar into said gap said crosslinking agent in the mortar reacts with said crosslinkable moieties in the resin of the anchor member and said terminal crosslinkable moieties in the mortar to provide chemical crosslinking between said part of the second portion of the anchor member and the mortar.

In a yet further preferred embodiment of the third aspect of the present invention, the method comprises the additional step of casting a layer of a skid resistant material on an exposed upper surface of at least one of the mortar cast into the gap defined between the structural members and the first portion of the anchor member. It is preferred that the layer of skid resistant material is cast on an exposed surface of both the cast mortar and the first portion of the anchor member. The layer of skid resistant material is preferably chemically bonded to said exposed upper surface of at least one of the mortar cast into the gap defined between the structural members and the first portion of the anchor member.

Preferably the skid resistant material comprises an organic polymer resin containing terminal crosslinkable moieties and a crosslinking agent. The resin is preferably selected from a group consisting of a polyester resin, a vinyl ester resin and an acrylic resin. The resin preferably contains chemical groups derived from an unsaturated organic monomer compound. The resin may contain moieties selected from a group consisting of styrene, vinyl toluene, acrylic ester and methacrylate ester (e.g. methylmethacrylate ester). The terminal crosslinkable moieties are preferably methacrylate ester moieties.

When the layer of skid resistant material is applied to the exposed upper surface of the mortar it is preferred that during casting said layer of skid resistant material the crosslinking agent in the skid resistant material and/or the crosslinking agent in the mortar reacts with the terminal crosslinkable moieties in the resin of the skid resistant material and the mortar to provide chemical crosslinking between the layer of skid resistant material and the mortar. Moreover, when the layer of skid resistant material is applied to the exposed upper surface of the first portion of the anchor member it is preferred that during casting said layer of skid resistant material the crosslinking agent in the skid resistant material reacts with the crosslinkable moieties in the resin of the anchor member and the terminal crosslinkable moieties in the resin of the skid resistant material to provide chemical crosslinking between the layer of skid resistant material and the anchor member.

Preferably said first and second portions of the anchor member are integrally formed.

A fourth aspect of the present invention provides an expansion joint assembly for location in a gap defined between first and second structural members, the assembly comprising a sealing member and at least one anchor member, said anchor member having a first portion for connection to the sealing member and a second portion for connection to one of said structural members, wherein a layer of skid resistant material is provided on an exposed upper surface of the first portion of the anchor member.

This aspect of the present invention is based on the realisation that the exposed upper surface of the anchor member represents a skidding risk in addition to the risk presented by the exposed upper surface of the mortar. In addition to the benefit in overcoming the risk of skidding, providing a layer of skid resistant material on the surface of the anchor member helps to protect the anchor member from wear and tear over the lifetime of the joint.

The second portion of the anchor member is preferably adapted to be connected to one of said structural members via mortar cast into the gap defined between the structural members. Additionally, a layer of a skid resistant material may be provided on an exposed upper surface of the mortar cast into the gap defined between the structural members. This layer of skid resistant material should help protect the mortar from general wear and tear.

A fifth aspect of the present invention provides a method for forming an expansion joint between first and second structural members comprising locating an assembly according to the fourth aspect of the present invention in a gap defined between said structural members; said locating of the assembly comprising connecting the first portion of the anchor member to the sealing member, connecting the second portion of the anchor member to one of the structural members and providing a layer of skid resistant material on an exposed upper surface of the first portion of the anchor member.

Preferably the layer of skid resistant material is provided on said exposed upper surface of the first portion of the anchor member by casting.

It is preferred that said connecting of the second portion of the anchor member to said one of the first and second members comprises casting mortar into said gap such that said mortar contacts the second portion of the anchor member and said one of the first and second members. Preferably a layer of a skid resistant material is cast on an exposed upper surface of the mortar cast into the gap defined between the structural members.

A sixth aspect of the present invention provides a method for forming an expansion joint between first and second structural members comprising locating an assembly comprised of a sealing member and at least one anchor member having first and second portions in a gap defined between said structural members; said locating of the assembly comprising connecting the first portion of the anchor member to the sealing member, placing the anchor member into said gap, casting mortar into said gap to connect at least the second portion of the anchor member to one of the structural members and providing a layer of skid resistant material on an exposed upper surface of the mortar cast into said gap, wherein during provision of said layer of skid resistant material, said layer of skid resistant material chemically bonds to the mortar.

The layer of skid resistant material is preferably provided on said exposed upper surface of the mortar by casting.

Having regard to the fourth, fifth and sixth aspects of the present invention, preferably the skid resistant material comprises an organic polymer resin containing terminal crosslinkable moieties and a crosslinking agent as hereinbefore described in relation to the third aspect of the present invention. The mortar preferably comprises an organic polymer resin containing terminal crosslinkable moieties and a crosslinking agent as hereinbefore described in relation to the third aspect of the present invention. It is preferred that the anchor member is formed from a material comprising an organic polymer resin containing crosslinkable moieties as hereinbefore described in relation to the third aspect of the present invention.

In preferred embodiments of the fourth, fifth and sixth aspects of the present invention the skid resistant material is chemically bonded to the anchor member and, where applicable, the mortar (when a skid resistant layer is provided on the surface of the mortar). The chemical bonding is preferably provided by the crosslinking agent in the skid resistant material and/or the crosslinking agent in the mortar chemically reacting with the various crosslinkable moieties in the skid resistant material, anchor member and, where applicable, the mortar in a similar way to that described in relation to the third aspect of the present invention. By chemically bonding the layers of skid resistant material to the anchor member and the mortar the skid resistant material is more resistant to being stripped from the surface of the joint, which is a common problem with conventional joints, and the skid resistant layer, anchor and mortar form an effectively homogeneous mass.

In the fourth, fifth and sixth aspect of the present invention said first and second portions of the anchor member are preferably integrally formed.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a schematic sectioned side view of a prior art EMR-RE joint;

FIG. 2 is a schematic side view of an EMR-RE joint in accordance with an embodiment of the present invention;

FIG. 3 is a schematic plan view of an anchor member forming part of the EMR-RE joint of FIG. 2;

FIG. 4 is a schematic side view of the anchor member of FIG. 3 connected to a structural member such as a road; and

FIG. 5 is a schematic side view of the anchor member of FIG. 4 with a layer of a skid resistant material.

FIG. 2 shows an expansion joint assembly 11 in accordance with an embodiment of the present invention which may be located in a gap defined between a pair of neighbouring road sections (not shown) to form an EMR-RE expansion joint.

The assembly 11 comprises an elongate elastomeric seal 12 interposed between a pair of opposed rails 13 that serve to anchor the seal in place. The seal 12 is of conventional design and possess a pair of outwardly extending lugs 14 for receipt in complementary grooves 15 defined in an inner surface 16 of each rail 13, thereby forming a dovetail connection. Each rail 13 is of a unitary structure and consists of an inner portion 17 corresponding to the steel rail 2 of the prior art joint 1 shown in FIG. 1 and an integral outer portion 18 which defines an elongate wedge-shaped locking member 19. The taper of the wedge is such that the thickness of the locking member 19 increases in the outwards direction. The inner and outer portions 17, 18 of the rail 13 are integrally formed as a single cast from a pultruded vinyl ester resin composite incorporating glass fibre to provide reinforcement.

It will be understood by the skilled reader that whilst the rails are shown in the figures to have sharp edges, in practice they are likely to be rounded to avoid the tendency of cracks to form in the resin at those edges and to avoid the entrapment of air in sharp internal angles.

Rectangular slotted apertures 20 are defined in each locking member 19 to accommodate an amount of mortar (not shown) when mortar is cast between the rail 13 and the adjacent road section to increase the strength of the connection between the rail 13 and the road section via the mortar. The apertures are elongate and extend in parallel to the longitudinal axis of the rails.

FIG. 3 illustrates a single rail 13 and shows the inner and outer portions 17, 18, and the apertures 20 described above in relation to FIG. 2. FIG. 3 also shows surface texturing 21 which has been applied to the locking member 19 to increase the surface area of the locking member 19 available to contact mortar when mortar is cast between the rail 13 and the adjacent road section. The texturing is an optional feature.

Referring now to FIG. 4, a single rail 13 is connected to an adjacent asphalt road section 21 laid on a concrete bridge deck 22. The rail 13 is connected to the road section 21 via an appropriate amount of vinyl ester resin based mortar 23 which is provided in a space defined between the rear and lower surfaces 24, 25 of the rail 13, the road section 21 and the deck 22.

FIG. 5 shows the same arrangement as FIG. 4 but with a layer of skid resistant material 26 cast on to exposed upper surfaces 27, 28 of the mortar 23 and the rail 13.

In order to form a joint between a pair of road sections 21 supported on a concrete bridge deck 22, two rails 13 are located in a gap between the road sections 21. The rails 13 are arranged in a face-to-face relationship as shown in FIG. 2 but without the seal 12 in place. Mortar 23 is then cast into spaces defined between the rear and lower surfaces 24, 25 of each rail 13 and the road section 21 and deck 22 to which that rail 23 is to be connected. Whilst the mortar 23 is curing the layer of skid resistant material 26 is cast on exposed upper surfaces 27, 28 of the mortar 23 and the rail 13. Finally, when the mortar 23 has cured, the seal 12 is interposed between the rails 13 and held in place by insertion of the lugs 14 of the seal 12 into the complementary grooves 15 defined in each rail 13. The wedge shape of the locking member 19, its textured surface and the slotted apertures 20 ensure that it forms an effective key with the mortar 23.

Each rail 13 is formed from a vinyl ester resin dissolved in styrene and processed into a composite which incorporates glass fibre reinforcement. The resin is not fully saturated (i.e. it contains one or more carbon-carbon double bond) and thus contains crosslinkable moieties. The mortar 23 and the skid resistant material 26 comprise a vinyl ester resin dissolved in an excess of methylmethacrylate monomer to provide a vinyl ester resin containing terminal methylmethacrylate groups and unreacted methylmethacrylate monomer as a crosslinking agent.

When the mortar 23 and the skid resistant material 26 are cast, the methylmethacrylate monomer reacts with the carbon-carbon double bonds in the vinyl ester resin forming the rails 13 and the terminal methacrylate groups in the vinyl ester resin in the mortar 23 and skid resistant material 26 to provide chemical crosslinking between the resin forming the rails 13, the resin in the mortar 23 and the resin in the skid resistant material 26. In this way, the rails 13, mortar 23 and skid resistant material 26 in the finished joint form a composite mass of essentially uniform chemical composition. The connection between the rails 13, mortar 23 and skid resistant layer 26 is thereby significantly stronger and more uniform than that in prior art joints. It also provides for greater longevity. Moreover, the present invention provides a joint possessing greatly improved physical and chemical compatibility between the rails 13, mortar 23 and skid resistant layer 26. Furthermore, since the rails 13 are formed from an organic polymer resin they offer much greater resistance to moisture and de-icing salt than the steel components used in conventional joints.

The design and construction of the expansion joint assembly also provides for reduced installation times, reduced component weight and reduced environmental risk by the elimination of toxic materials.

While a specific embodiment of the present invention has been described above it will be evident to the skilled person that the assembly of the present invention may take any convenient size and/or shape to suit a particular application. The inventive assembly may be used to form an expansion joint assembly between any two structural members and is not limited to use in road or bridge construction. For example, it is envisaged that the assembly of the present invention may be used to form a joint between structural components using in the construction of buildings or other civil engineering structures. The first portion of the rail may take any suitable form to provide a connection with the seal and the second portion of the rail may have any desirable configuration, including any suitable form of surface texturing, as long as it facilitates a satisfactory connection between the rail, the mortar and the adjacent structural member.

Moreover, the anchor member whilst being described as a wedge shaped member may take any suitable form that serves to interlock mechanically with the mortar. Furthermore, the organic polymer resins forming the rail, mortar and skid resistant layer should be chosen such that their physical and chemical compatibility fall within acceptable limits. It is particularly preferred that the rail, mortar and skid resistant layer are made from materials which incorporate chemical groups which can react to provide chemical bonding between these components to strengthen the connection between the rail, mortar and skid resistant layer, and in turn the neighbouring structural member.