Building material for making dams or walls in underground mines - contains large amt. of fly ash obtd. from electrostatic filters in coal burning power stations

摘要

The parent patent described a building material used for making dams, back-up walls, or for lining tunnels in underground mines. The novelty in the present invention is that the material includes more than 25% of fly ash collected in the electrostatic filters of coal-burning power stations, so the disposal costs involved with fly ash are further reduced. The building material pref. also contains 2.5% CaC12, 2H20, and 0.3-2.0% stearates, esp. aluminium stearate. The material has adequate strength for use in underground mines despite its high content of fly ash. In an example a mixt. contained ca. 60% gypsum; Ca. 5% anhydrite; more than 25% fly ash obtd. from electrostatic filters; 10% portland cement type 350; 2.5% CaC12, 2H20; and 0.3-2% aluminium stearate used to accelerate setting.