Structural solidification in tunnel is quite special. Face consolidation and umbrella injection in tunnelling or gallery driving secure fault zones. They secure brittle mountains and rocks. The rock or substrate to be secured is differentiated according to its pore volume, which determines the choice of the injection material. ARCAN organo mineral resins stabilise and consolidate rock, gravel and coarse sand. For substrates with fine pores, BoRox AC is the first choice. For the filling of cavities and caverns the choice to be made between foam and organo mineral resins.