Lightweight sand-lime bricks from sand, calcareous binder and water - contain plastics particles which melt during firing to leave pores

摘要

Mfr. of lime bricks from a mixt. of sand, calcareous binder and water, comprises hydrothermally hardening the brick blanks which are produced by compacting-moulding. To the mixt. foamed plastics particles e.g. polystyrene beads, melting at hardening temp. are added at the rate of 20-50%, based on vol. of the mixt. which is then compacted in moulds, by vibration, and the resulting blanks are then hydrothermally hardened in known manner. The fused plastics particles leave pore-type cavities in the blanks. The prod. has an apparent density of only 600-800 kg/m3. Hardening is effected under vapour pressure of 10-20 bar at 180-210 degrees C. The foamed polystyrene beads have particle size 1-5 mm. The mixt. contains 10-20% humidity. The pores are of even size, their walls being evenly coated with the fused polystyrene.