PREFABRICATED CONSTRUCTION ELEMENTS BASED ON PLASTER, WHICH PRESENTS WATER RESISTANCE.

摘要

Prefabricated water-resistant construction element, comprising a substrate based on hardened plaster, said substrate being capable of being obtained by means of at least the following steps: (a) homogeneous mixing of a dry matter comprising mostly at least one hydratable calcium sulfate, a hydrophobicizing agent comprising at least one silicone compound, and water, and preforming in the wet state said substrate; (b) drying of the preformed substrate, to obtain said substrate formed in solid and dry state; characterized in that the homogeneous mixture, prior to preforming in the wet state of the substrate, also comprises a mineral additive comprising, on the one hand, a clay material, non-swelling in aqueous medium, and which does not incorporate hydroxyl function in aqueous medium, and on the other hand a crystalline silica, said mineral additive having a synergistic affinity of hydrophobicity with said silicone compound, within, or thanks to the addition of, mineral additive to the homogeneous mixture; the hydrofugation of the substrate in solid and dry state, is increased by at least 20%, in Cobb equivalent, according to ASTM 630 / 630M-96a, and / or for the same hydrofugation (or water resistance), the amount of hydrofugation agent is reduced by at least 20%.