Baublatt Österreich 2023: Austria’s first pile breaking machine impresses on the “Stadtstrasse” project

For Gnant, the latest technology was never an end in itself, but always served to optimise processes. The most recent example is the impressive première of Austria’s first pile breaking (pile head milling machine) during the construction of the “Stadtstrasse” in Vienna. The highly developed Brextor attachment from the Swiss manufacturer BRC was used in combination with a Komatsu PC210LC-11 and a fully hydraulic SW3-Q quick-change system with rotary motor from Baumaschinentechnik. Based on a close co-operation with BRC, Gnant now also offers this technology as a service provider in Austria.

The foundation stone for the Gnant company’s success story was laid in 1959 by Josef and Leopoldine Gnant, who transported milk with their own company. A few years later, the company entered the building materials trade, marking the beginning of a dynamic development that led to a constant expansion of expertise. Today, the family business, which is managed by Josef Gnant in the third generation, employs around 200 people. The head office in Wimmersdorf has been expanded in recent years and adapted to the new size of the company. The range of services offered includes earthworks projects of all sizes, excavation landfills, raw material extraction, transport as well as demolition and processing of construction waste at the company’s own recycling centre. Managing Director Josef Gnant: “Gnant stands for concepts with which we develop creative and efficient solutions for our customers. In civil engineering, for example, we offer earthworks in combination with excavation support as a turnkey excavation concept. The latest technology plays an important role here, for example in the areas of digitalization and 3D modelling, which we entered around 15 years ago. We are now working intensively on optimizing the networking of data between the construction machine on site and our technology department. The aim is not to set an excavator in motion unprepared. Instead, we want to use a professional preparation process to prepare the project as a digital model. All processes are optimized in advance by our own employees and then implemented precisely by the construction machine with 3D control. We are now also using this approach to increase productivity on smaller construction projects. This means that we avoid any unnecessary excavation and can work very cost-efficiently, because this effort pays off with every cubic meter. However, the issue of sustainability is also very important to us, where we are pioneers in implementing construction projects as sustainably as possible, including in connection with the use of biosynthetic fuels.

We attach great importance to providing our employees with comprehensive support, because the customer also notices how much they enjoy their work.” The team has a modern, versatile and extensive fleet of vehicles at its disposal, including around 80 trucks. The approx. 120 construction machines range from 1 t electric excavators to 55 t tracked excavators. Josef Gnant comments: “Gnant is not only characterized by a large number of construction machines, but also by a large number of special attachments to meet every customer requirement, including in the area of soil stabilization. Our excavators from 21 tons upwards have been equipped for many years with quick-change systems and attachments from Baumaschinentechnik. For decades, we have relied almost exclusively on the Komatsu brand for large equipment.

Our 55 t excavator, the demolition machines with super long front equipment and the crawler tractors are all Komatsu machines. Accordingly, we have a long-standing partnership with Kuhn, with which we are very satisfied. The way in which problems between our two owner-managed companies are resolved quickly, in a spirit of partnership and constructively is an important quality for us. The support provided by Christian Schmidt and the service team is outstanding. That is why we have once again opted for three PC210LC-11 excavators, a PC228USLC-11 short-tail excavator and two WA475-10 wheel loaders as part of our latest investment package. Shortly before that, we had already purchased a PC210LC-11, which was optimized for use with the BRC Brextor pile breaking machine.” Christian Schmidt, the responsible supervisor at Kuhn Baumaschinen, celebrates the 50th anniversary of the company and is proud to have maintained a successful partnership with Gnant for two generations. Around 60 machines are currently in use in the Gnant fleet. In addition to earthmoving machines from Komatsu, this also includes several processing and screening plants for the extraction of raw materials. In addition to the hydraulic excavators, the WA475-10 wheel loader has also proven itself at Gnant in terms of efficiency, productivity and fuel consumption. Thanks to the latest equipment package, Gnant now has three WA475-10 wheel loaders from Komatsu in operation.”

Brextor pile breaking machine: horizontal milling instead of vertical hammering

Bored piles fulfill a wide variety of tasks and in many cases are connected to a floor plate or a concrete beam. The necessary pile breaking is usually carried out by hand using breaking methods, which represents an enormous physical strain. Other negative effects include noise pollution for local residents, cracks in the concrete structure and, as a result, corrosion damage due to water ingress. BRC Engineering AG, an owner-managed company based in Rain, Switzerland (canton of Lucerne), has developed the BRC Brextor pile breaking machine as an efficient alternative to other breaking methods. It can be used to remove excess concrete without causing damage, as the horizontal direction of rotation of the breaking tools prevents uncontrolled cracks in the concrete structure. The contact surface remains 100% load-bearing and corrosion damage caused by water penetration is avoided. From the alignment of the milling head to the exposed reinforcement, the processing of a pile with a diameter of one meter and a height of one meter takes about 45 minutes, which corresponds to about 10 times the speed compared to manual processing. The shorter and more precise operation of the BRC Brextor generates significantly less noise and vibration than conventional methods. The modular system offered by BRC offers great flexibility and is suitable for different pile types from 40 to 200 cm in diameter. The BRC Brextor can also be used in confined spaces and with so-called energy piles, which work with heat pipes like a geothermal probe, without any problems. The BRC Brextor had its Austrian premiere during the construction of the Stadtstraße in Vienna. This is intended to ensure good connections between the dynamic growth region in the north of Vienna and other urban areas and connects the A23 south-east bypass with Seestadt Aspern. Bmstr. Engineer Dominik Horacek, MBA, supervised the work on site as project manager for Gnant: “As part of the construction of the city road, Gnant was commissioned by Porr to cut off around 120 bored piles in an initial section. These serve as slope protection for the tracks of the eastern railroad that runs here and are connected with a concrete bar. In the run-up to the project, the employees involved completed several days of training at Brextor in Switzerland. This training is the requirement for certification by Brextor and therefore for working with the pile breaking machine Brextor. Our team was supported by two employees from Brextor, who were on hand to advise us. We were able to complete this section on time and to the client’s complete satisfaction.

The immediate inspection of the piles by experts not only confirmed the high quality of the milling work, but also the clean and smooth pile appearance.” So how does the milling process work in detail? First, Brextor the pile breaking machine is aligned, which centres itself automatically using sensor-controlled technology. After milling, the pile head is milled to the desired level. The core tension is broken with the inner cutter and the surface tension with the outer cutter in a single work step. The remaining concrete edge can then be broken away from the reinforcement with the Brextor LC110 cutter without risk of damage. If necessary, the pile head can be reworked with a small milling disc. The Komatsu PC210LC-11 was equipped with technology from Brextor and Baumaschinentechnik for use with the pile breaking machine.

Quick-change system: work without interruption

The fully hydraulic quick-change system SW3-Q from BMT, with which the Komatsu PC210LC-11 is equipped, was designed for easy tool changes on hydraulic excavators from 23 to 40 tons. With Oil-Quick function and five automatically connectable hydraulic connections
with an oil flow rate of up to 378 liters/min. hydraulic breakers, demolition and sorting grabs and other special attachments can be fitted with
extremely high oil flow rates, such as this pile breaking machine, can be changed in seconds without risk. Josef Gnant: “Our structure is characterized by a very flat hierarchy. On this basis, our employees are always on the lookout for new technical solutions. When we became aware of the pile breaking machine last fall, Dominik Horacek was already in Switzerland shortly afterwards and only a few weeks later we established the cooperation with Brextor. This enabled us to agree the cooperation for Austria. Brextor’s aim is to establish the technology on the European market after 15 years of development. This means that Gnant acts as a competence center for trade and services related to Brextor products in Austria. If you compare Brextor with the manual breaking methods from an economic point of view, then the milling of bored piles should be included in every tender. This protects our workers from an extremely strenuous activity, prevents sick leave in the short term and expensive treatment in the long term.” In future, Gnant will offer all construction and specialist civil engineering companies a complete service package comprising carrier, machine operator and the three Brextor attachments. Depending on further orders, the purchase of a further pile breaking machine for larger bored pile diameters of up to 1,600 mm, such as those used in traffic route construction, is being considered.