At the Qatalum smelter, ComBAR was used to reinforce the floor slab of the rectifier area.
Schoeck signals end to rebar corrosion
Schoeck says its high-strength glassfibre reinforcing bar offers a highly durable solution to eliminate rebar corrosion in the region.
01 June 2011
SCHOECK Middle East claims to offer a guaranteed solution to the problem of steel rebar corrosion, one of the primary causes of damage to reinforced concrete structures in the Middle East.
Schoeck ComBAR, developed by Schoeck Bauteile of Germany, is a reinforcing bar made of highly corrosion-resistant glass fibres and an extremely durable diffusion-tight vinyl ester resin matrix that effectively addresses the problem.
“The material is much stronger and stiffer than commonly known glassfibre reinforced polymer (GFRP) bars,” says Christoph Spitz, managing director of Schoeck Middle East. “The high fibre content and the linear alignment of the fibres are achieved in the pultrusion process, which is used in the production of the bars.”
Helical ribs are cut into the hardened bars to ensure an optimal bond between the rebar and the surrounding concrete. “This is essential when the bars are to be placed close to the concrete surface or in slender concrete elements, such as facade plates and pilasters. The finished bars are then coated to guarantee their extreme durability even in chemically aggressive environments,” he explains.
In the harsh environment of the Middle East, it is not uncommon that concrete structures require extensive maintenance and repairs as early as 10 years after going into service. Various measures are undertaken today to mitigate rebar corrosion, ranging from the installation of epoxy-coated or stainless steel rebar to the sealing of the entire surface of the concrete structure, he says.
“With the development and market introduction of Schoeck ComBAR, a high-strength glassfibre reinforcing bars, a new, highly durable solution is now available to eliminate rebar corrosion,” he claims.
To bring ComBAR and the associated benefits to the region, Schoeck Bauteile set up Schoeck Middle East, its sales office in Dubai in early 2010.
“When we brought ComBAR to the Middle East, our primary focus was to provide the highest possible quality technical consultation services to our customers,” says Spitz. “We believe that this is an ideal solution to the woes of many developers, designers and engineers in this region and we are fully committed to serving this region to an international standard.”
ComBAR has been certified in Germany, the Netherlands, the US and Canada, according to European and North American codes and guidelines. In the Middle East, it has been certified by the Dubai Municipality and tested at the King Fahd University for Petroleum and Minerals (KFUPM) in Saudi Arabia and at the Arab Centre for Engineering Studies in Doha, Qatar.
The rebar’s durability has been tested under load at elevated temperatures in moist concrete according to the testing concept published by the International Federation for Structural Concrete (fib) in its Technical Bulletin 40, Spitz states.
“Several ComBAR bars are tested to failure during this procedure. The applied stresses are plotted as a function of the time-to-failure on a doubly logarithmic scale. From the data points, the time-to-failure line is determined. The characteristic values of the tensile strength of the material can then be extrapolated using this line for the tested environmental conditions. This can be done for design service life spans of up to 100 years. The 100-year values are specified in the technical documentation of ComBAR,” says Spitz.
Speaking of its application, he says that in highly-corrosive environments, the installation of ComBAR bars ensures a greatly extended service life of concrete structures, minimising the required maintenance and repair cycles and thereby reducing the overall lifecycle costs. For this reason, ComBAR was installed at the seafront restoration project in Blackpool, England, and at a royal villa in Qatar.
In addition to being corrosion resistant, ComBAR is also non-magnetic and does not conduct electric currents. Hence, it is often installed in electrical facilities near or below machines operating under high currents, such as transformers and reactors, eliminating stray currents and the associated energy losses in the machinery.
ComBAR has been installed in the floor slab of the rectifier area of Qatar Aluminium’s (Qatalum) smelter and in several reactor buildings throughout Europe.
Other fields of application include tunnelling projects, where the bars are installed in the areas of concrete diaphragm and drilled pile walls, which are to be penetrated by the tunnel-boring machine; and in infrastructure projects such as railways, where the material is installed because of its electromagnetic properties. For the same reason, the material is also installed in research institutions and hospitals in the vicinity of electromagnetically-sensitive machinery such as transfer electron microscopes.
