STATE-OF-THE-ART corrosion-resistant rebar from Germany’s Schock is playing a key role in protecting a seafront villa for Qatar’s royalty.

Elaborating on the project, a company spokesman says: “On the beach of the capital city Doha, the royal family has built a beautiful residence with a seafront view of the western Arabian Gulf,” says a company spokesman. “The villa is placed directly on the beach in the splash zone. A lot of interesting features give the building a special character. One of them is a 31-m-long L-shaped retaining wall from the building to the seaside to protect the royal family compound. A significant issue in the design was the very aggressive environmental conditions, due to the high content of chloride in the sea-water, aggressive soils, high temperatures and humidity.
“In the design phase, it was quickly clear that an extraordinary solution was needed to deal with these environmental conditions, as ordinary steel reinforcement is known to suffer severe deterioration by corrosion in similar projects within less than 10 years. This was the reason why engineers from Schock were involved in the planning and engineering of the retaining wall from the beginning. As a specialist for reinforcement technology, Schock provides an alternative reinforcement to steel called Combar.”
Combar is a glassfibre reinforced polymer (GFRP) reinforcing bar, which offers all the benefits of steel in terms of design, tensile strength and bonding properties, but is much lighter and easier to handle.
“The material is chemically resistant, non-magnetic, non-conducting and easily machined. On account of its corrosion resistance, Combar was used in the royal villa,” he says. “The bar contains a vinyl ester resin which is ideally suited for special environmental requirements. In combination with high-grade, high-strength E-CR glass fibres, an extremely durable reinforcing bar was developed by Schock. The modulus of elasticity of the rebar is greater than 60,000 MPa. Their tensile strength is well above 1,000 MPa. Comparative tests on concrete slabs reinforced with the same cross-section of steel rebar and Combar show the benefits resulting from this extremely high strength.”

100 years design life
Extensive independent tests have been carried out  on Combar in Europe, Canada and in the Middle East by the Arab Testing Centre, the Dubai Municipality and by the King Fahd University.
“The tensile strength and the bond behaviour have been tested in short-term and in long-term tests,” he says. “In the long-term tests, a large number of bars were tested at different temperatures (23 deg C, 40 deg C and 60 deg C). Each bar was subjected to a constant tensile stress until it failed. The stress levels were successively reduced until the time to failure exceeded 5,000 hours. The times to failure of all the tests were plotted versus the corresponding applied stresses. Using statistical methods, the design tensile strength was derived from this plot. This value guarantees a life-time of the bar of at least 100 years in any type of environment and structure, including the warm and chemically aggressive marine surroundings encountered in the Middle East.”
But it is not the product performance alone that customers can rely on. “The package Schock delivers is extremely comprehensive, including the product itself and an extensive array of services. The customers benefit from assistance with initial consulting, dimensioning, preparation of drawings, development of project-specific solutions and, of course, full support with on-site supervision of the installation itself. At the Qatar Aluminium factory (Qatalum), Combar was installed with this support in more than 1,000  sq m of foundation slab in the rectifier area of the plant. Large machines operate at extremely high currents in this section of the smelter. Currents induced in the steel rebar of the foundation slabs below these machines would have led to a heating up of the bars, ultimately resulting in their failure,” the spokesman says.
Schock has grown to become Europe’s leading supplier of innovative structural load-bearing insulation products. Its headquarters are in Baden-Baden in southern Germany.
Subsidiary companies are located in the UK, Canada, France, Austria, Switzerland, the Netherlands, Poland and Hungary. Sales teams and partners operate in many other European countries and also in the Middle East. Schock is committed to providing the highest level of technical back up and comprehensive customer service to the construction industry. The ISO 9001-certified. Schock aims for the highest quality standards and focuses on the conservation of the environment.