Hochtief Aktiengesellschaft Vorm. Gebr.helfmann

Richard Pohl

Bernd Hillemeier

Gunter Brockmann

The apparatus for applying a sprayed concrete layer to a surface comprises a concrete feed pipe for a pumpable and sprayable concrete mixture made with water, a sprayer and a compressed air feed device for compressed air under a pressure of several bar from a compressed air source. The concrete feed pipe opens into the sprayer which has a compressed air connector device. The concrete mixture is sprayable with the compressed air. The compressed air feed device comprises a register including several compressed air chambers which connect to and open into the compressed air connector device. The individual compressed air chambers are connected with the help of control valves in alternating sequence to a power silo for loading a powdery concrete additive, particularly silica powder, or for blowing through a compressed air partial flow.

Method of and apparatus for applying a sprayed concrete layer to a

A spray concrete composition which is sprayed with driving-air pressure has its setting time accelerated by incorporation in the driving air of amorphous silica dust having an inner surface (specific surface area) of at least 25 m.sup.2 /g.

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Walldorf, Germany

Richard Pohl