SCC for Concrete Segment Molds

At present the company presents a unique tubbing production method manufacturing precast concrete segments without vibration. This is achieved by the working steps inclination of the mold, injection of the SCC from bottom up and curing in traditional horizontal position.

Safety improvement & better working conditions by

» Elimination of noise pollution and risks involved in the vibration process

» Avoidance of difficult processes concerning the segment surface

Durability and quality by

» Longer service life of the mold

» Simplified maintenance

» Higher quality segments

Efficiency by

» Shorter concreting cycles

» Less manpower

» Cost optimization

Standard Concrete vs. SCC

 Self-compacting concrete has a very soft consistency and this texture makes it very easy to compact without any vibration. Nevertheless, its practical use in precasting demands a high technical level due to the complexity required concerning the segment molds. This had been the reason challenging the Research and Development Department of CBE Group: They concentrated on the possibility to adapt the existing precision mold to the SCC method. Should they succeed in designing a mold that endures the different mixtures of the fluid SCC, often containing metallic fibers? And how does the mold react to the pressure of the concrete injection?

These questions served as the basis of the subsequent experimental studies with the newly designed mold.
Its distinctive feature is the inclined position during the casting process and the reason is obvious: the injection
of the fluid SCC under pressure in inclined position leads to a continuous and homogenous flow and possible air voids will be evacuated naturally by bubbling up to the surface.

Numerous tests carried out under real conditions revealed that the injection of self-compacting concrete results not only in a quieter but also faster concreting process. The following curing will be carried out in the traditional horizontal position.

Results

The first de-molded segments seemed to be promising and proved that they were on the right track: accurate, smooth and uniform tunnel segments without the necessity of often difficult tasks such as additional surface finishing and treatment of the gasket grooves.

Cost effective

As the financial aspect is always a key factor in tunnel construction, the SCC mold has a significant impact on the budget: due to the elimination of expensive vibrators as a source of noise pollution and the reduction of the safety risk for the workforce, the service life of the mold is also increased without the stressing part of the vibration.

Moreover, the first sales of the SCC molds revealed an obviously shorter concreting cycle when used in a precast carrousel system.

CBE Group holds a pending patent on the SCC segment mold and is the only supplier worldwide. As usual and like all their formwork, the SCC mold is available for all kind of projects and all diameters.

The company CBE Tunnel had been founded in 1987 by Robert Salmon. 2005, the qualified engineer, Didier Lefebvre, took over the company and established the holding company Lefebvre CEF, in which he holds the majority, gathering all companies under the new CBE Group since January 1, 2006. Now, CBE Group has a good reputation world-wide thanks to its experience of more than 25 years in the field of mold manufacturing in more than thirty countries all over the world and an export sales volume of 95 % of the total turnover. The international success story of CBE began with the supply of molds for the construction of the Channel Tunnel.

Until today, CBE Group supplied numerous customers with 250 precast concrete segment plants, 110 of these as carrousel system for 13,000 segment molds that produced 11,000,000 concrete segments for 2,300 km of
tunnel lining.

CBE Group has committed itself to the dynamics of growth on its international market with the intention to continue to increase its market share in a still developing sector significantly: China. Following the first projects in 2002, 2004 and 2005, CBE Group had founded CBE Group Asia with an office in Beijing in 2008. Then, CBE Group Asia established an own production site in Yangling with 100 employees operating since 2009.

At the end of 2009, the holding Lefebvre CEF acquired the two supply companies Acimex and Meca Vega, that complement the Group with know-how in the field of steel machining (Meca Vega) and in the technology of vacuum handling (Acimex).

Today, CBE Group has a workforce of 208 people of
six nationalities speaking ten different languages.