High performance, non-stop. Wirtgen slipform pavers build Berlin Brandenburg International Airport

Transcription

1 High performance, non-stop Wirtgen slipform pavers build Berlin Brandenburg International Airport

2 1.5 million square metres of concrete paved to perfection Berlin is Germany s largest city and home to 3.5 million people. For historical reasons, the capital is served by three small airports which, twenty years after the German reunification, are continuously exceeding their capacity limits. This situation will come to an end very soon: since September 2006, Berlin Schönefeld Airport has been expanded to become the capital city s new Berlin-Brandenburg International Airport, or simply BBI. A whole fleet of Wirtgen slipform pavers are playing a major part in the construction work. They are building the taxiways, manoeuvring areas and aprons as well as the southern runway, covering an impressive total area of 1.5 million square metres. Given its huge dimensions, highest quality requirements and extremely tight schedule, the project is a big challenge for everyone involved including the teams operating the Wirtgen slipform pavers. Concrete paving was therefore scheduled right from the start to take place in shift operation around the clock. Deadline pressure has considerably increased yet again due to the hard and very long winters of 2009 and The client is pressing for completion on schedule nonetheless and without compromising on quality. Fleet of Wirtgen slipform pavers in non-stop operation For the purpose of implementing this extraordinary project, contractors Gebrüder von der Wettern, Eurovia VBU and Eurovia Beton formed the ARGE BBI GU II joint venture, which in turn contracted execution of the work to ARGE BBI GU II Luftseitige Flächenbauwerke (ARGE BBI GU II Airside Traffic Infrastructure), a joint venture comprised of Eurovia VBU, Max Bögl Bauunternehmung and Eurovia Beton. The companies already owned large Wirtgen slipform pavers type SP 1500, SP 1500 L and SP Image: Axel Heise, Eurovia

3 South becomes North The southern runway of Schönefeld Airport will serve as the northern runway of the new airport. The scope of new construction includes an entirely new terminal building with direct rail connection as well as an additional, 4 km long runway to the south. State-of-the-art technology and an excellent infrastructure will soon offer both business travellers and tourists everything air passengers could wish for. Berlin among the world s Top 50 airports Opening of the new airport is scheduled for mid The hub to the east will then commence operations with an initial capacity of 27 million passengers per year. The slipform pavers from Wirtgen are in operation around the clock. Working at an advance speed of just over 1 m/min, they are placing the 40 cm dual-layer concrete pavement with utmost precision. This will make Berlin not only number three among the German hub airports, surpassed only by Frankfurt and Munich, but also one of the top 50 airports worldwide. Their machines have been in non-stop operation since May 2008, paving concrete on the extensive areas day after day and night after night. Two slipform pavers type SP 500 are in operation at the same time to complete smaller sections. Now and then, weather conditions thwart the schedules set by the planners but weather-related delays need to be compensated for nevertheless. When this happens, the dependability and excellent performance of the Wirtgen slipform pavers are real assets for the paving crews. Pavement structure with an overall thickness of 130 cm The new southern runway alone encompasses an area of 240,000 m², impressing with a length of 4 km and a width of 60 m. To enable even giant aircraft like the A 380 to land and take off at BBI Airport, a pavement structure in concrete design with an overall thickness of 130 cm was realized both on the southern runway and in all of the other movement areas totalling 1.5 million m² altogether. The subgrade is composed of a 50 cm thick layer of improved soil, a 15 cm thick layer of stabilized soil, and a 25 cm thick hydraulically bound base course. A 40 cm thick concrete slab rests on top of the subgrade. 2 // 3

4 6,000 cubic metres of concrete in a single day Our joint venture will be placing some 600,000 m³ of pavement concrete altogether over the entire project term. If everything goes smoothly, a large Wirtgen concrete paver is capable of processing 6,000 m³ of concrete within 24 hours, says senior site engineer Christoph Hofmeister. Tremendous daily performance rates like these can only be achieved with accurate planning, efficient logistics and smooth, highly efficient teamwork. Concrete supply is one of the most important aspects. The raw materials for concrete production are ordered in advance based on monthly requirements planning. Based on detailed weekly and daily planning including current weather forecasts, the specified quality and quantity of concrete is then produced and supplied to the paver train just at the right time. To master this challenge, as many as 50 trucks are available for concrete transport. Given the huge dimensions and enormous deadline pressure of the entire project, reliable operation of the slipform pavers is extremely important. For these large machines to work efficiently, material supply must go like clockwork. Only then can the machines operate at their full potential, explains Christoph Hofmeister. Optimal paving quality and performance of the large pavers are achieved at an advance rate of just over 1 m/min, which requires delivery of approx. 6 m³ of concrete per minute. This equals one truckload every 3 to 4 minutes twenty-four hours a day. Five slipform pavers complete 1.5 million square metres At times as many as three large slipform pavers an SP 1500 L, an SP 1500 and an SP 1600 are in operation on the runways and taxiways at the same time. They are paving concrete in a single-course, dual-layer operation. The same type of concrete is used for both layers (33 cm bottom layer and 7 cm top layer). Between the layers, dowel bars are positioned at evenly spaced intervals by the automatic dowel bar inserter. To produce the correct level and slope, the experienced airport builders use transducers scanning a stringline or slab tracers scanning the previously paved concrete slab. Compliance with highest quality requirements Concrete quality is ensured by a sophisticated quality plan with extensive, continuous internal and external testing both at the source material and at the completed concrete slab. The paving gangs working at the slipform pavers are responsible for the paving quality: We are processing fairly stiff concrete here so that paving is greatly facilitated by the weight of the Wirtgen machines and their excellent compaction performance, say paving managers Michael Lakotta and Hero Sauer. The pavers compaction performance results from their favourable configuration and matching vibrator power, which ensure uniform compaction of the concrete.

5 Christoph Hofmeister, senior site engineer Max Bögl Group It is a fascinating experience to collaborate on such a large-scale project, and an opportunity you don t get often in life, says the senior site engineer. The biggest challenges are posed by the huge project dimensions. After all, concrete paving alone will keep us busy for three years despite the fact that we are working around the clock. Aircraft still land and take off at the old Schönefeld Airport. Some 2 km to the south, the paving trains are producing the concrete pavements of the southern taxiway A and B systems at working widths of up to 15 m. Evenness is ensured by the finishing beam and super smoother. Two texture curing machines type TCM 1800 follow behind the pavers, applying the broom finish as well as a dispersion serving as a liquid curing compound. A peakto-valley depth of more than 1 mm gives the concrete good tyre adhesion. Premature drying of the concrete is prevented by applying a layer of approx. 220 g of dispersion per square metre. Constant wind and the high peak-to-valley depth necessitated such large amounts of curing compound to reliably prevent the formation of cracks. Depending on weather conditions, the broom finish and dispersion are applied separately by two separate machines, thus enabling the optimal time to be chosen for each of these operational steps. Frank Zimmermann, senior site engineer Eurovia Beton Concrete quality is ensured by a close-knit system of internal and external testing. On the joint venture s part, a team of laboratory engineers keep monitoring and documenting material quality around the clock. A foreman keeps checking the dowel bar positions. The site management is informed immediately about any deviations. Additional tests are performed after hardening of the concrete. If the quality isn t as it should be, the machines are stopped and the causes identified. Paving continues only after all quality criteria have been met. Michael Lakotta and Hero Sauer, paving managers We are paving fairly stiff concrete here at a layer thickness of 40 cm, which is around 30% more than that of motorway pavements. The vibrators installed in the Wirtgen slipform pavers supply the power required for compacting the concrete to specification. Another factor just as important as compaction is evenness. With the levelling systems from Wirtgen, it is no problem at all for us to realize the specified evenness and slope. Patrick Stryj, graduate engineer becker bau bornhöved We will be producing up to 2 million cubic metres of concrete over the entire project term. The six mixing plants can produce up to 900 cubic metres of concrete per hour. The largest item by far is the construction of roads and movement areas, which will require a total amount of some 1.3 million cubic metres of concrete altogether. In peak periods, we produce concrete for the slipform pavers at a capacity of 600 m³ per hour. 4 // 5

6 Concrete layers In a first step, the 50-cm bottom layer consisting of non-cohesive and cohesive soil was improved and stabilized to specification by means of cement. The next layer is composed of a 15-cm stabilized mixture of hydrophobic cement and frost-proof sand. To complete these operations, the contracting companies relied on several Wirtgen soil stabilizers type WR 2500 S. This layer is followed by a 25-cm hydraulically bound base course. In a final step, the slipform pavers placed a 40 cm thick concrete layer between vertical formwork with sinusoidal cross-section. 600,000 cubic metres in top quality During construction of the new airport, concrete quality is ensured by a quality plan which governs type and frequency of the accompanying material tests. These tests include, for example, temperature, water-cement ratio, degree of compaction and air content. Uncompromising quality is ensured by a system of internal and external testing both at the mixing plant and on the paving site. Additional tests are performed during and after the paving operation, such as flexural strength and compressive strength tests. The evenness is checked using a rolling straight edge. It must comply with the requirements specified in the ZTV Beton (Additional technical contract conditions and guidelines for construction of roadways surfacings made of concrete) of less than 4 mm over a length of 4 m. The cross slope must be between 0.7% and 1.5%. High-performance concrete for BBI Airport Materials and processes need to meet extremely high quality standards in the BBI construction project. We use an air-entrained crushed aggregate concrete of compressive strength class C35/45 that is capable of taking extremely high loads. This material is able to withstand the tremendous static and dynamic loads imposed by the big aircraft just as easily as the high temperatures generated during landing or the application of de-icing agents in winter, says Patrick Stryj, senior engineer at the concrete plant, explaining the choice of material. In up to six high-performance concrete mixing plants, which are in operation around the clock, up to 11,000 m³ of concrete per day can be produced for both pavement and building construction. A special highlight is the state-of-the-art transhipment facility which transports 1,200 tons of cement per train right into the plant s working or storage silos. The concrete plant of bbb: construction materials are supplied by rail to ease the strain on roads and environment. Litmus test for a perfect surface fi nish After placing, the concrete needs to set and harden over a period of several days. A defined water content in the concrete is necessary to ensure optimal progress of this chemical process. Paraffinbased curing compounds are therefore applied in Germany to prevent premature drying. The water contained in the dispersion evaporates in the process while the wax particles adhere to one another at their contact points. A wax film is thus formed which delays evaporation of the water in the freshly paved concrete and results in a much slower decrease of the water content. Researchers at the Technical University of Munich have identified and defined the optimal time for applying the curing agent as slightly moist condition of the concrete surface. In the field, it can be determined by using the so-called litmus test. In the process, a strip of litmus paper folded into a circular shape is placed on the concrete surface and held down by means of a small weight. The optimal time for applying the curing agent is when a freshly placed strip of litmus paper does not change colour within 60 seconds. In critical weather conditions, this simplified procedure was also used at BBI Airport to determine the optimal time for application of the dispersion. When outside temperatures were low, the optimal time for application of the curing agent was much later than the optimal time for applying the broom finish. In weather conditions like these, perfect concrete quality and texture could only be achieved by using two texture curing machines: one for applying the broom finish, and one for applying the dispersion.

7 Flexible machine design Repositioning and modification of the concrete pavers are major aspects influencing the efficiency of a project planned and carried out under great pressure of time. During repositioning, in particular the SP 1500 L and its twotrack design impressed with easy handling. The concrete slabs in the different sections were placed in courses of different widths, which required the pavers to be modified several times to working widths ranging from m to 15 m. The job was carried out by the site teams to save the time and costs otherwise incurred for machine transport. A strong team: joint venture partners Max Bögl and Eurovia Beton provide one paving gang each for each of the Wirtgen paving trains. Reliability counts Machine reliability is of the essence in view of 24-hour operation, firm orders for specific quantities of concrete and extremely tight deadlines to be met. For precisely that reason, the joint venture partners rely on Wirtgen machines. Fast expert service is yet another aspect that scored top marks in Berlin. Cooperation with Wirtgen s sales and service company in Windhagen is excellent. There can be no doubt about that in view of up to 2,000 hours per paver per year, states graduate engineer Hakon Schalk, head of the Mechanical Engineer s Department. Senior site engineer Frank Zimmermann adds: We achieve such high daily output rates because the majority of checks as well as maintenance and repair work are performed right here on the construction site. To complete these jobs, we use the time frame that is available when the machines are cleaned at the end of the night shift. Expert service technicians from Wirtgen accompany the project, supporting the teams on site if required. Our well-trained staff handle many things themselves, and Wirtgen always provides perfect support with any other work that needs to be performed on the machines. In case of an emergency, their staff can always be contacted via a 24-hour hotline. Quite a logistical challenge: as many as 50 trucks are needed just for concrete transport. Expertise is the key effi ciency driver A major building block for the successful completion of a largescale project is well-trained staff, says senior site engineer Frank Zimmermann, explaining the philosophy of his company. Martin Datzert, service and sales consultant at Wirtgen Windhagen, trained the team in intensive courses during the long winter months: The operators were familiar with their machines even before the training began. Training in small groups enabled us to deepen their knowledge further. A major aspect of training is quick troubleshooting. Malfunctions were therefore hidden in the pavers electric and hydraulic systems for training purposes. Martin Datzert explains why: Malfunctions need to be detected quickly on site as concrete already delivered to the pavers must be processed within a short time. Another important training subject are regular, independent machine checks. The acquired know-how enables machine operators to identify wear and tear in good time before any extensive repair stoppages become necessary. High availability of the joint venture s slipform pavers and rapid progress of the construction operation are thus ensured. 6 // 7

8 Illustrations and texts are non-binding and may include customized fittings. Subject to technical changes. Performance data depend on operational conditions. Nr EN-04/11 by Wirtgen GmbH 2011 Printed in Germany Wirtgen GmbH Reinhard-Wirtgen-Str Windhagen Germany Phone: +49 (0) / Fax: +49 (0) / Internet: info@wirtgen.com