Abstract: A regenerative heating and melting device is disclosed for treating asphalt concrete rubble for the recovery of an asphalt coated aggregate suitable for reuse. The apparatus includes a vertical cylindrical casing, an inlet for hot gas and an outlet for exhaust gas, conveyor means for conveying the rubble to the top of the casing and means for recovering the regenerated paving material from the casing. The internal space of the cylindrical casing is divided into a plurality of tier sections by partition plates. Each of the plates has an opening means to communicate with the adjacent lower tier section. A rotary shaft is provided in the cylindrical casing, the axis of which coincides with the axis of the cylindrical casing and extending through the tier sections and partition plates.

Abstract: A porous inorganic product which is excellent in acoustic absorptivity and filtration efficiency and is high in strength is produced by bringing suitably sized organic foam particles, which have elasticity and can be shrunk greatly by heating or can be dissolved in a solvent, into contact with one another under pressure so as to deform each thereof, filling the gaps present between the organic foam particles with an inorganic binder such as cement, hardening the inorganic binder to form a hardened material, and shrinking the organic foam particles contained in the hardened material.

Abstract: A gypsum wallboard or plasterboard having a high mechanical strength, especially high impact strength, and a large bulk density is prepared from a mixture consisting essentially of calcined gypsum, cellulosic fibers, asbestos fibers, a setting retardant for the calcined gypsum and water, by withdrawing solid components of the mixture in layer form. A plurality of the thus-obtained layers is piled to form a preform of the desired thickness and pressure-molding the preform under a molding pressure of from 10 to 400 kg/cm.sup.2 to obtain the board product.