Patent ID: 6355191
Filing Date: 2002-03-12
Classification: B28B,B28C,C04B

Abstract:
Method of manufacturing cementitious products consisting essentially of an inert granulated natural stone material and a cementitious matrix binding for filling voids and interstices of the granulated natural stone material, providing for the following steps:a. providing an inert granulated natural stone material as a starting material having a predetermined and controlled particle size; b. calculating a void fraction of the inert granulated natural stone material and calculating a theoretical quantity of cementitious matrix binding sufficient to fill the voids and interstices of the granulated natural stone material from the calculated void fraction; c. preparing a cementitious matrix binding for filling voids and interstices of the inert granulated natural stone material consisting essentially of a water and cement slurry having a water content of between 0.25 and 0.36 parts by weight relative to the weight of the cement wherein the water and cement slurry is supplemented with a quantity of a known plasticizing additive for cementitious slurries such that, when the cementitious matrix binding is subjected to a â€œmini slumpâ€  test, the cementitious matrix binding has a fluidity such that the cementitious matrix binding can be arranged in a very thin layer with a rounded shape having a diameter of about 20 cm; d. intimately mixing the inert granulated natural stone material and a quantity of the cementitious matrix binding such that the quantity of the cementitious matrix binding is slightly in excess of the theoretical quantity of the cementitious matrix binding calculated from the calculated void fraction of the inert granulated natural stone material; e. spreading the mixture of step (d) in a forming device to form a layer of desired thickness in the forming device; f. deaerating the layer in the forming device by applying a very high vacuum of not less than 40 mm Hg to the layer in the forming device for a period which is very short but long enough to bring about a substantially complete deaeration of the interstices and to remove all air remaining incorporated in the layer to form a deaerated layer; g. applying a vibratory motion with a frequency of between 2000 and 4800 cycles per minute to the deaerated layer upon termination of the deaeration step under high vacuum of not less than 40 mm Hg and under a lower vacuum than that of the deaeration step between 70 and 80 mm Hg for a period of a few tens of seconds to about 3 minutes to provide relative settling of particles of the inert granulated natural stone material in the deaerated layer and surface closing of the deaerated layer; h. transferring the forming device to a setting and initial hardening section; and i. removing the product from the forming device and keeping of the product on shelves for a final hardening of the product.