Innovative process enables damage-free removal of iron-reinforced concrete piles
More and more often, the available building land is in exposed locations and has poor load-bearing capacity. For this reason, pile foundations are becoming increasingly important. Because the pile cap is the connection to the foundation, high quality without compromise is required for its processing. A patented process from Switzerland ensures high efficiency and control when breaking the pile caps.
Until now, bored piles have mainly been processed with air or hydraulic hammers that work with vertical impact energy. Because this energy cannot be controlled, cracks in the concrete body and spalling on the outer skin of the pile can occur during processing. This can cause corrosion damage in the medium term. In addition, reinforcement bent or torn off by air or hydraulic hammers can reduce the tensile load-bearing capacity. Due to the design of these appliances, a correspondingly large working area is also required.
Forces under control
The Brextor process from BRC ensures damage-free removal of the excess concrete, as the horizontal direction of rotation of the milling cutters prevents uncontrolled cracks in the concrete structure. In addition, the pile cap is transferred to the downstream pile with high precision (height accuracy +/- 1 cm). The core stress is broken with the Brextor inner cutter and the surface stress with the Brextor outer cutter. The remaining concrete edge can then be removed with the BRC pile head crusher without any risk to the reinforcement. The design of the attachment allows it to be used with very little or even no lateral working space, which saves on excavation work.
According to the manufacturer, Brextor can also work much faster than traditional methods – partly because manual labour can be completely dispensed with. From the alignment of the milling head to the exposed reinforcement, the processing of a pile with a diameter of 1 m and an excavation height of 1 m takes around 30 minutes. Brextor is suitable for all pile types and walls. The standardised system makes it easier for site personnel to use. In addition, the excavated material (80 % 0 to 30 mm gravel) can very often be processed directly on the construction site.
1. prepare pile with milling disc 2. milling down to level 3. breaking out the remaining concrete and 4. Cleaning and aligning the reinforcement.
Proven in practice
Brextor convinced those responsible at Implenia AG to extend the four lanes at Liestal railway station. In this project, great importance is attached to the timely execution of the work, as the construction work is being carried out during ongoing railway operations. “The time pressure on this construction site is great, as various milestones have to be met,” confirms lmplenia construction manager 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.”
Any other solution would also be economically unattractive due to the limited space available on the construction site. As the space between the nail wall and the pile head is too small for a hammer, the wall, which is up to 6 metres high, would have to be set back over a length of 300 metres in order to be able to work on the pile head in the traditional way.
The Brextor process saved on excavation, transport, landfill fees and material replacement for this project. In addition, the reduction in truck journeys has lowered the CO2 footprint and eased the traffic situation around the construction site.
bpzsays: If building loads do not have sufficient load-bearing capacity due to unfavourable ground conditions, then pile foundations are used. In order to subsequently enable an optimal connection of the piles to the base plate, the excess concrete of the piles must be removed cleanly and precisely. A new, patented solution brings more control to this process compared to the conventional breaking method, and cracks in the pile body are avoided.
Original press release in German.