A safety barrier and a process for its production

Abstract: In a road safety barrier of the type including at least one elongate beam (7) which has fixing means (9) for its connection to support elements and which extends horizontally between the support elements, the beam includes a core (10) of synthetic resin reinforced with a mixture of continuous glass fibres and continuous steel wires extending parallel to the longitudinal axis of the beam, and can be produced by pultrusion.

Description: The present invention relates to a road safety barrier of the type including at least one elongate beam which has fixing means for its connection to vertical support elements and extends horizontally between the support elements, the beam including a core of synthetic resin and being obtainable by pultrusion. The safety barriers currently in use are normally made of various materials such as steel, galvanised iron and concrete; however, these materials have disadvantages connected with their cost and/or their heavy weight. US-A-3 233 870 describes a road safety barrier of the above-mentioned type, with an elongate beam including a core of synthetic resin, which can be produced by pultrusion. DE-U-6 942 683 describes a road safety barrier with a beam made by casting in a mould, including steel bars as inlays in a core of synthetic resin reinforced by means of a glass fibre mat. There is a need to provide safety barriers of a new construction which are lighter and less expensive and which, at the same time, have good mechanical strength characteristics. For this purpose, a subject of the invention is a safety barrier as defined by the appended claims. The synthetic resin in which the reinforcing fibres and wires are incorporated is preferably a thermosetting resin, preferably an unsaturated polyester resin which can provide adequate resistance to atmospheric and chemical agents and to thermal stress, as well as good impact strength, which is an essential characteristic for safety barriers. However, the use of other types of resin such as, for example, bisphenolic resins is not excluded. In comparison with other materials, glass-fibre-reinforced polyester resin offers various advantages, the main advantages being: a better breaking-load to weight ratio; its weight is about 2/3 of the weight of aluminium and 1/4 of the weight of steel, good resistance to corrosion and to the transfer of heat, good impact strength, dimensional stability and a substantial absence of deterioration due to atmospheric agents so that maintenance operations are not necessary. It has been found that the combined use of glass fibres and continuous steel wires further improves, in particular, the impact strength characteristics. Steel wires, which have good mechanical strength together with excellent resistance to stretching within their elastic range, allow further stretching in the permanent deformation range without breakage. These characteristics ensure that, in the event of a very violent impact, the vehicle is restrained within the carriageway since the protective barrier is deformed without being broken. Typically, the continuous glass fibres and steel wires are disposed in alternating bundles so as to ensure uniform mechanical strength. Typically, the mixture of fibres and wires includes from 1 to 70% by volume of glass fibres and from 1 to 70% by volume of steel wires with reference to 100% of the total volume of fibres and wires, preferably from 30 to 70% of glass fibres and from 70 to 30% by volume of steel wires. The ratio by weight between the fibres and the wires with respect to the total weight of the core is typically between 15 and 80%, preferably about 20-50% by weight. The resin constituting the matrix may also include mineral fillers such as calcium carbonate and silicates; the core produced by pultrusion includes up to 50% by weight of fillers incorporated in the matrix resin. Further advantages and characteristics of the safety barrier according to the invention will be described with reference to the appended drawings, provided by way of non-limiting example, in which: Figure 1 is a schematic illustration of the pultrusion process, Figure 2 is a perspective view of a beam constituting a safety barrier, and Figure 3 is a section taken on the line III-III of Figure 2. Manufacture by the pultrusion process illustrated schematically in Figure 1 is a known method in which each fibrous reinforcing filament ("roving") is completely impregnated with resin, preheated and stretched, after which the impregnated reinforcing filaments are brought together and drawn through a long heated die which confers a predetermined shape. The high density of fibrous elements and the considerable pressure to which they are subjected means that all the spaces and residues of material are eliminated, making the finished product very homogeneous and compact. The resulting product is a prestressed structural component. In the method according to the invention, the bundle of "roving" includes steel wires which are immersed in the matrix resin. With reference to the drawing, supply means, schematically indicated 1, supply the glass fibres and the steel wires which are passed through a tank 2 in which they are wetted and/or impregnated with the synthetic resin. The time spent in the tank and the metering of the resin are regulated so as to ensure adequate impregnation and wetting. The fibres and steel wires are brought together in a preforming device 3 in order to position them for admission to a die 4 which is heated by electrical resistance and from which a section 7 is drawn and is cut to the desired lengths by means of a cutting machine 6. The section 7, which is intended to constitute the beam element of the safety barrier shown in Figures 2 and 3, has a corrugated cross-section which defines a channel 8 in order to improve its bending strength characteristics. Through-holes are indicated 9 and, in the embodiment illustrated, act as fixing means for anchorage to vertical uprights, not shown. It is intended that the fixing means, as well as the upright supports, may have any configuration which is practical, according to the specific application. The beam element 7 may also have other configurations, for example, a hollow box structure, which can also be produced by the pultrusion process. As shown in Figure 3, in addition to a core 10 formed by glass fibres and steel wires disposed parallel to the axis of the section, and impregnated with the synthetic matrix resin, the cross-section of the beam element or section 7 may also include one or more reinforcing layers 11, 12 formed by glass-fibre "mats" with the fibres preferably disposed in perpendicular bundles. According to a further characteristic of the invention, the synthetic resin may be filled with a luminescent or chemiluminescent material or with substances suitable for reflecting a light beam. For these purposes, for example, flakes or microspheres of glass or quartz may be incorporated in the synthetic resin as fillers. Alternatively, luminescent or reflective materials may be applied to the surface of the beam element as surface layers. For example, surface layers of flakes or granules of glass or a similar reflective or refractive material may be applied by a method which comprises sticking the flaked material onto an auxiliary support strip by means of an adhesive, feeding the strip thus produced through the pultrusion die so as to cause the strip to stick to the pultruded core as a surface layer, and then removing the auxiliary strip so as to leave the reflective material exposed and adhering to the synthetic resin.

Claims: A road safety barrier, including at least one elongate beam (7) with fixing means (9) for its connection to support elements and extending horizontally between the support elements, the beam including a core (10) of synthetic resin and being obtainable by pultrusion, characterised in that the core is reinforced with a mixture of continuous glass fibres and continuous steel wires extending parallel to the longitudinal axis of the beam. A safety barrier according to Claim 1, characterised in that it includes one or more reinforcing layers (11, 12) formed by fibre "mats" disposed on one or both faces of the core. A safety barrier according to Claim 1, characterised in that the beam has a corrugated cross-section. A safety barrier according to any one of Claims 1 to 3, in which the core includes from 15 to 80% by weight of fibres and wires with reference to the total weight of filaments and resin. A safety barrier according to any one of Claims 1 to 4, in which the core includes from 1 to 70% by volume of continuous glass fibres and from 1 to 70% by volume of steel wires with reference to the total volume of fibres and wires. A safety barrier according to any one of Claims 1 to 4, characterised in that the core includes from 30 to 70% by volume of continuous glass fibres and from 70 to 30% by volume of steel wires. A safety barrier according to any one of Claims 1 to 6, in which the synthetic resin includes luminescent and/or reflective substances. A safety barrier according to any one of Claims 1 to 6, in which the elongate beam includes at least one surface layer of reflective material formed by granules or flakes of reflective material incorporated in the surface of the synthetic resin.

Inventors: GAROFALO ERCOLE, MUSTO MARIAGRAZIA, GAROFALO, ERCOLE, MUSTO, MARIAGRAZIA
Applicants: SIGEM SRL, SIGEM S.R.L.
Application year: 1992
Main classification: E01F15
IPC codes: B29C70, E01F15