Pannon Gabion Kft. planning and construction of retaining walls

www.pannongabion.hu

Postal address:
2051 Biatorb�gy, Hat�r u. 1
Ware-house: 2051 Biatorb�gy, BOSMARK Erd�v�ri Ipartelep
Telephone/fax: 23 / 311199
Mobile: 30 / 9516899
E-mail: info@pannongabion.hu

ViaCon Helcor corrugated steel pipe installation technology (concreting)

M7 motorway sections 202 + 598 km récsei stream

Background:

The background and preconditions for the concreting work:

The concreting work is not necessary for reasons of statics or corrosion prevention, etc., its only purpose is to fill in the gap between the ROCLA and the HELCOR galvanised corrugated steel pipe to prevent any possible washing in from occurring. The concreting work must be carried out with great care so as to avoid the pipe floating up on the concrete but to ensure that the gaps are filled in completely. The smallest cross section that is to be filled in is 50-60 mm in the most critical sections. A precondition of the concreting work is the supporting of the pipe elements in accordance with the approved plan and technological instructions. Geodesic survey. The approval of the Engineer for the concreting work.

Concreting:

The filling of the gap was tried and tested in the case of the MÁV Zrt. reconstruction work carried out in the past, concrete (mortar) satisfying the above conditions was injected using a Putzmeister M 750 D mortar mixing and pumping machine.

The mortar mix is injected in between the pipe structures in 0.22 m3 mix batches at a pressure of 7 bar through two concreting heads from the influence area.

During the concreting work the flow base level must be continuously measured so as to avoid the mortar lifting the pipe structure.

Mix composition:

• 210 kg/m³ cement CEM II/B-M (V-L) 32.5 N Beremend cement factory
• 100 kg/m³ limestone powder (to prevent sedimentation) CARMEUSE Beremend
• 550 kg/m³ 0/4 washed sand (Letenye gravel pits)
• 2 kg/m³ Centripor SK 120 air-entraining agent (plasticity, density reduction) MC Bauchemie Kft.
• 155 kg/m³ water

Mix characteristics:

1000 kg/m³ body density, 4-5 N/mm³ step-resistant solidity

Amount to be concreted: 80 m³.

Approx 10 minutes of mixing time should be allowed in order to achieve the desired air-entraining, concreting duration approx. 5 days.

There is no real alternative to the technology described above for the following reasons:

• The work area may only be access from the influence area and not using heavy-duty vehicles from the immediate vicinity in dry weather.
• The impulse nature of the operation of concrete pumps may result in the pipe floating up, besides this it is difficult to insert the pipe into the installation pipe.
• Traditional mixes become separated and due to their non-mortar consistency they are not suitable for injecting even with the use of plasticizer.
• The process may be interrupted and monitored at any time.

After the daily concreting work has been completed the "flying" pipelines have to be removed from the installation pipe and washed along with the concreting heads. The concreting must be continued and the air pushed out until the concrete appears at the influence area.

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