The testing of chemical additives and special extruders in order to reduce dust at the work place during spray concrete work

Status:

completed 11/1993

Aims:

Spray concrete technology, which has many applications, has a procedural disadvantage in that it produces a great deal of dust with a corresponding health risk for those involved (in particular during the construction of tunnels in excess pressure situations). The basic options for reducing dust through additives (dust binding agents) have already been investigated. The results showed that binding agents in powder form were more effective than liquid. A further improvement through additional pre-wetting remains uncertain after preliminary investigation. Goal: evaluation of existing indications of the effectiveness of different dust binding agents and pre-wetting parameters.

Activities/Methods:

Tests on the spray concrete test bed with systematic variation of the dust binding agent and pre-wetting.

Results:

The lowest amount of dust formation is, in contrast to previous assumptions and approaches (e.g. dust binding agent), achieved through the combination of liquid hardening accelerators with an appropriate pre-wetting nozzle. The optimum spray concrete extruder for this purpose is to be developed in a future project.

Publications:

Praml, Hartmann, Droz, Kessel, Fruhmann: Spritzbeton im Tunnelbau - Die langfrisitge Entwicklung der Staubexposition. Zbl Arbeitsmedizin 45 (1995) S. 86-93

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