Rail construction projects, by nature, always present a number of key challenges for any contractor. With the time pressures involved under strict possessions, efficiency is crucial to the success of a project.

One factor that can affect the smooth running of a project is the use of wet concrete products. Quality can be compromised by late possessions, obstructions and lengthy travel distances, which can cause the concrete to segregate and cure ahead of placing in the pile or foundation.

Specialist ground engineering contractor Van Elle Rail identified and overcame this problem by developing a solution in the form of a state of-the- art on-track volumetric mixer. First of its kind in Europe, the computer-controlled mobile batching plant RRV is capable of dispensing specific concrete mixes whenever needed.

Onsite production

Volumetric mixing is a technique of producing concrete at the location of the works rather than batching off site. The raw concrete ingredients (cement, water, aggregate) are proportioned volumetrically before being mixed. It allows for production of only the required amount with each batch, as well as topping up if more is needed.

Using this process, concrete quality can be maintained at all times, offering better performance, improved workability and savings on cost and programme. In addition, by ensuring that only the exact amount of concrete is mixed as it is required, significant savings can be realised on production, transportation of any extra material to the site, and disposal of any excess concrete remaining.

Different types of aggregate can be mixed with cement consecutively with the volumetric system, as each ingredient is stored in separate compartments, ready for mixing as and when needed. The user has complete control over the proportions added to the mix throughout the process, allowing for modification at every stage whilst meeting design requirements.

Being onsite, the risk of a premixed batch becoming hydrated or segregated in transit – especially on hot days, or in heavy traffic – is almost entirely removed. Similarly, if more concrete is required for a project than was originally thought necessary, there is no delay waiting for extra to arrive onsite, during which time the already poured mix may begin to cure.

Increased efficiency

Van Elle Rail’s on-track volumetric mixer has a significant advantage over more traditional methods of concrete delivery. The mixer simply accesses the track, travels to the work site, batches the required amount of concrete and returns back to the RRAP in order for the materials can be replenished ready for the next possession.

It is a truly efficient method, and a vital one, given the small window of opportunity under strict possessions.

The volumetric mixer is capable of dispensing 7.4m3 of concrete and, if a greater volume of concrete is required, it can easily be replenished on track using RRVs and trailers. It is ideally suited for blockade work, remote locations and isolated works.

This method also reduces Van Elle Rail’s carbon footprint as there is no need for multiple trips to and from a batching plant. Multiple deliveries can be made to sites with just one load, making smaller trips far more feasible economically.

On-track Volumetric Mixer

Designer: Van Elle Rail.
Manufactured: King Trailers.
Vehicle: Mercedes Actros 3 3344/4500 6×4. Rail equipment: Zweiweg type 2623 rail bogies.
Volumetric plant: Reimer PA950-50, 7.4m3/ batch, 50 m3/h.
Compliance: RIS-1530 PLT.
Gauge conformity to W6a