DUBAI, UAE -
Completion set for November 2012
The striking Lekki-Ikoyi Link Bridge in Lagos is Nigeria's first cable stay bridge. It's a landmark construction project that has seen the main contractor, Julius Berger Nigeria PLC make use of advanced construction techniques and products to overcome environmental and logistical challenges and meet stringent design specifications. BASF Construction Chemicals' high performance admixtures and building system products were vital ingredients.
The bridge joins two upmarket districts in Nigeria, namely Lekki and Ikoyi on Lagos Island, and will help relieve the massive congestion in and around Victoria Island. Initiated in 2009, it has taken considerable engineering and construction knowhow to bring the bridge close to completion. The new road link is set to open for public traffic in November 2012.
The 1.357 meter long Lekki-Ikoyi Link Bridge comprises a 722-meter full-span approach bridge and the main cable stayed segmental bridge of 635 meters in length at the center of which is a 90-meter high pylon. Walkways on both sides of the bridge are two meters wide and the width of the two main carriageways -- east- and westbound respectively -- will be
2 x 4 meters each.
The challenges faced included building the 90m-high pylon and bridge above water in segments, handling heavy weights up to 250 tons. The contractor also had to overcome access and traffic challenges throughout the construction of the bridge, and had to ensure the batching plant was producing concrete of a sufficient type and quality.
All works were done above water and Julius Berger Nigeria's Health, Safety and Environmental skills were essential throughout to account for the unique hazards of this particular environment. The German subsidiary Julius Berger International GmbH (formerly Bilfinger Berger Nigeria GmbH) handled the planning, design and support of Julius Berger Nigeria, including logistics and supply of materials and equipment that were difficult or impossible to procure inside the country.
Says John Gilbertson, Business Development Manager, West Africa for BASF Construction Chemicals: "This was the first cable bridge to be built in Nigeria and to be considered successful it needed to meet high functional, engineering and aesthetic standards. The BASF solutions, used successfully internationally and elsewhere on the African continent, assisted to smooth construction processes and meet engineering standards." Key to servicing this site was the logistics to ensure supplies were available when they were needed and technical skills from BASF were available onsite to test and monitor the quality of the concrete put out by the batching plant.
While the segments for the bridge superstructure - the approach bridge as well as the main bridge - were cast in the precast yard, the concrete for the foundation piles and the pylon had to be transported to site. Challenges with regard to this casting process include getting the concrete mix just right so that it remained workable for an appropriate length of time in the hot and humid climate. It also needed to be of the right consistency - i.e., pourable - to enable suitable filling of formwork. The early, high and final strength of the concrete also needed to be just right to enable a suitably rapid pace of work to be maintained. And last, but hardly least, aesthetics were important.
Julius Berger had to achieve a fine and smooth finish on all concrete segments.
Says Gilbertson: "The finish of the concrete is superb and comfortably similar to that found in Europe. In addition, our levels of service and pricing met their unique needs in this difficult working environment."
The BASF products
Rheofinish 202 is a chemical release agent. It was applied to mould and shutter faces by spray prior to casting the concrete in order to achieve a clean release. After removal of the formwork, the resultant concrete has a smooth hard uniform finish, with reduced incidence of blow holes.
Pozzolith LD 50, a high performance concrete plasticiser and water reducing agent with set retardation properties, increased the early and ultimate strengths of the concrete. It is designed to optimise hydration of the cement paste, subject to the mix design. When compared to a control concrete, 28 days strengths are achievable in seven days and, similarly, seven-day strengths are achievable within three days. The advantages of Pozzolith LD 50 include improved workability and increased compressive strength, increased impermeability and durability, and improved surface finish.
To facilitate ease of casting, BASF's Rheobuild 561M, a high range, water reducing superplasticiser for rheoplastic concretes, was selected. Rheoplastic concrete is a fluid concrete with a slump of at least 200mm, easily flowing, but at the same time free from segregation and having the same water/cement ratio as that of a low slump concrete (25 mm) that does not make use of admixtures. Rheobuild 561M is formulated from synthetic polymers specially designed to impart Rheoplastic qualities to concrete.
Looking to the future
The Lekki-Ikoyi Link Bridge may be the first of several cable bridges in Nigeria. Says Gilbertson: "BASF is pleased to have been part of this project. It's an important first for the country and for Julius Berger. The success of the project has strengthened the relationship between Julius Berger and BASF, and we look forward to collaborating with them on future projects."
BASF is the world's leading chemical company: The Chemical Company. Its portfolio ranges from chemicals, plastics, performance products and crop protection products to oil and gas. We combine economic success, social responsibility and environmental protection.
Through science and innovation we enable our customers in almost all industries to meet the current and future needs of society. Our products and system solutions contribute to conserving resources, ensuring healthy food and nutrition and helping to improve the quality of life. We have summed up this contribution in our corporate purpose: We create chemistry for a sustainable future. BASF posted sales of about EUR73.5 billion in 2011 and had more than 111,000 employees as of the end of the year. BASF shares are traded on the stock exchanges in Frankfurt (BAS), London (BFA) and Zurich (AN). Further information on BASF is available on the Internet at www.basf.com.
About BASF Construction Chemicals
BASF's Construction Chemicals division is the leading supplier of chemical systems and formulations for the construction industry. Continuous innovation and tailor-made solutions ensure its customers are more successful. Its product portfolio comprises admixture systems, cement additives, solutions for underground construction, repair systems and performance grouts, expansion control systems, waterproofing solutions and sealants, flooring systems, tile fixing systems, wall systems and solutions for wood protection. The division operates production sites and sales centers in more than 60 countries and achieved sales of about EUR2.2 billion with approximately 7,000 employees in 2011.
About Julius Berger
Julius Berger Nigeria Plc is a Nigerian construction company headquartered in Abuja FCT. An employer of 18,000 people of close to 40 nationalities, it is a multi-service, solutions-driven company and is unique in its long standing delivery of quality, capacity, reliability and excellent performance, all at internationally recognized standards.
Through Julius Berger International in Germany, Julius Berger Nigeria can unlock expansive knowledge on cutting edge construction technologies, provided by highly trained engineers and architects. Procurement of materials and supply which cannot be done locally is guaranteed by logisticians and procurement experts.
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United Arab Emirates
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