Process for the manufacture of a light constructional material, which can also be used inter alia as a packing or insulating material, and which contains expanded vermiculite

摘要

A constructional material is prepared by mixing expanded vermiculite, a water glass binding agent, and a mineral containing combined aluminium or combined magnesium, or which consists of calcite, to form a pulp-like to paste-like mass which is treated with a solution of a metal salt of pH value of 1 to 5, the metallic cation or cations of which has or each has an atomic weight of 24,32 to 65,38, the mass being progressively permeated by the metal salt solution, without any substantial disturbance of the mass, with formation of the metal silicate, whereafter the mass is dried and hardened. The metal salt may comprise aluminium sulphate, chrome alum, magnesium sulphate, zinc sulphate, ferrous sulphate, or ferric chloride. The mineral is preferably kaolin but may comprise magnesium oxide, talc, bentonite, or feldspar. The mass of expanded vermiculite containing the water glass and the other additive may be permeated with the metal salt solution by immersing the mass in the latter, or the salt solution may be drawn by suction through the mass.