New method developed
Quantum leap in pile breaking achieved
from Alois Portmann
Due to the increase in high-density construction and building in exposed locations, pile foundations continue to gain in importance. Previous pile breaking methods involve risks that can be avoided with the newly developed Brextor method, according to the manufacturer.
Rain/Switerzland (ABZ). –The world is becoming increasingly crowded. The annual population growth rate is currently 2%. The necessary building land is becoming increasingly scarce and thus the call for high-density construction is growing ever stronger. The available building ground is increasingly in exposed locations and of poor load-bearing capacity. Pile foundations are the solution to ensure a secure foundation in such conditions. For this reason, pile foundations are becoming increasingly important. The pile head is the connection to the foundation. The highest quality is required without compromise. A foundation failure can end in disaster.
Until now, bored piles have mainly been processed using air or hydraulic hammers. Air or hydraulic hammers work with a vertical impact energy. This processing energy cannot be controlled. As a result, there is a risk of cracks in the concrete body and spalling on the outer skin of the pile. This can cause corrosion damage in the medium term. Bent or torn reinforcements caused by air or hydraulic hammers further reduce the tensile load-bearing capacity.
Due to the design of these devices, a correspondingly large working area is required. Furthermore, narrow and long reinforcements are difficult to work with. This can cause major obstructions to existing spiral reinforcements in the excavation area. To ensure quality and to break the surface tension, a cut must also be made to the final height. The last 30 to 50 cm can only be done by hand.
With Brextor, the work process remains under control. The horizontal application of force enables 100% control of the processing energy used. In addition to the best possible quality, the pile head is handed over to the subsequent works with precise accuracy (height accuracy ± 1 cm). In addition, the concrete structure and reinforcements remain intact.
The core tension is broken with the Brextor inner cutter. The surface tension is broken with the Brextor outer cutter. The remaining concrete edge with the reinforcement inside can be broken away with the BRC pile head crusher without risk of damage.
This means that the finished bored pile head can be produced in four steps:
- Prepare pile with milling disk
- Milling down to level (± 1 cm height accuracy)
- Breaking out the residual concrete with the BRC pile head crusher
- Cleaning and aligning the reinforcement.
Brextor is manufactured in Switzerland, is a CAD designed construction and contains CNC machined precision parts. The process is patented worldwide.
New application possibilities
The design of Brextor allows it to be used with very little or even no lateral working space. This saves excavation work. The cut at the finished removal height to break the surface tension is made automatically with the outer cutter. The cleaning effort is reduced to cleaning work. According to the manufacturer, Brextor is suitable for all pile types/walls. The uniformity of the system makes it easier for site personnel to use. In addition, the excavated material (80 % 0-30 mm gravel) can often be further used on the construction site.
Four-lane expansion in Switzerland
Brextor was used for the four-lane extension at Liestal station, which was carried out by Implenia. The expansion of the northern and southern station entrances to four lanes should ensure significantly fewer crossing conflicts and more punctual and disruption-free rail traffic for long-distance, regional and freight traffic.
“With manual pile breaking, there would always be a risk of damaging reinforcements and disturbing the concrete quality at the pile head. I can rule out this risk with Brextor,” confirms Stefan Lang, construction manager at Implenia.
Saving time and workspace
The client attaches great importance to the work being carried out on schedule, as the four-track extension is being carried out during ongoing rail operations. “The time pressure on this construction site is great, as various milestones have to be met,” confirms Stefan Lang. “We only have a limited time window available and if this cannot be massively extended, such an undertaking without the Brextor would only be possible with a lot of resources and personnel.”
Time as a decisive factor was supplemented by the challenge of very limited space. Stefan Lang: “We would also need more space, which would be a major challenge here, as there is not enough room for a pointed hammer between the nail wall and the pile head. For
this reason, the wall, which is up to 6 m high, would have to be moved back over a length of 300 m just to create enough space for the pile breaking. This would mean a massive increase in costs. Thanks to Brextor, you save these costs.”
In the case of a railroad line extension, 80 cm of working space could be dispensed with on the rear side. Bei einer Böschung von 6 m Höhe, auf eine Distanz von 300 m ergibt das 1440 m³ Aushub, der nicht gemacht werden musste.
In addition to the enormous cost savings for excavation, transportation, landfill fees and material replacement, Brextor has made a major contribution to the environment and the local population.
At least 280 truck journeys of 40 km each were saved. This reduced the carbon footprint and the population benefited from a less congested road transport network.
BRC Engineering AG will be represented with Brextor (www.brextor.com) at bauma 2022 with its own booth. Brextor will be demonstrated live on around 400 m² and various Brextor models will be on display. The live demo of Brextor will take place daily (except Sunday) at 11 am, 1:30 pm and 4 pm.
The author is CEO of BRC Engineering AG.
Original press release in German.