Schöck promotes innovative ComBar
01 October 2006
Schöck Bauteile, a German manufacturer of innovative construction products for the static-construction sector, is actively promoting its innovative ComBar, a reinforcement technology for concrete suitable for tunnelling applications where the reinforcement must withstand enormous forces.
ComBar, a glassfibre reinforced polymer (GFRP) reinforcing bar which offers all the benefits of steel in terms of design, tensile strength and bonding properties, is much lighter and easier to handle, according to a spokesman for the company. The key to ComBar’s special properties as a reinforcing bar is the pultrusion manufacturing process, he says.
The spokesman explains: “Basically, this is a method by which the raw materials – plastic resin and continuous glassfibre – are ‘pulled’ together under heat, rather than ‘pushed’ as in the case of extrusion, to form a composite rod which is ideally suited to applications where high strength, thermal stability, weather and corrosion resistance are required.
“With its ribbed surface and a bond behaviour and stability comparable to BST 500 steel, ComBar is particularly suitable for tunnel construction. The high pressures in tunnelling partly results from the constant pressure of the earth – which makes special demands on the tensile strength of the material – and from tunnelling heads with diameters of more than 13 m that are driven through the head walls of the launching shafts and also through the shaft reinforcement.
“We are well-reputed for our core competencies in the noise insulation and thermal insulation fields, but over the last few years, reinforcement technology has become another mainstay for us. For concrete reinforcement requirements, steel has been used almost exclusively, but there are special considerations when faced with issues such as corrosion resistance, electrical insulation and chemical attack – areas in which steel is found wanting. The ComBar system really comes into its own in these situations.”
Citing a prestigious project where the reinforcement is currently being used, he says: “The new north-south route of the Amsterdam subway where 75 tonnes of ComBar has been used is one of the more prestigious projects of our company that has helped change people’s thinking in terms of reinforcement for international tunnel projects. The ComBar glassfibre reinforcement is embedded in six diaphragm walls and a reinforcement cage is braided with straight bars, stirrups and double headed bolts, which will then be concreted to provide the required stability of the diaphragm wall. The low material weight simplifies the processing during the reinforcement layout,” he adds.
Tunnel construction though is only one of the possible application areas for Schöck ComBar.
Since ComBar has thermal separation effects and is also non-magnetic and electrically insulated, it can also be used in the construction of houses, roadworks, harbour building, medical facilities and power supply facilities or as foundations in corrosive ground, the spokesman points out.
Based in Baden-Baden in southern Germany, Schöck began developing glassfibre reinforced polymer-reinforcing bars in 1995.
