Method and apparatus for the manufacture of cementitious slab products
OwnerMarcello Toncelliinventor
Life of this patent
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Abstract
A method and apparatus for preparing single layer tiles or slabs from a mixture of a granulated stone material having a selected particle size, and from a slurry formed by cement, a quantity of between 0.25 and 0.36 parts by weight of water relative to the weight of cement, and a plasticizer for cementitious slurries, in which the quantity of slurry added is slightly in excess of the quantity corresponding to the void fraction of the granulated material, in forming mould, containing a layer of predetermined thickness of the mixture, to be subjected to a first very short deaeration step under the effect of a very high vacuum and to a subsequent vibration step under a lower vacuum, after which the mould goes on to seeing and hardness steps.
Claims30
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 “mini slump” 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.
Plant for the manufacture of cementitious slab products from a mixture consisting essentially of an inert granulated natural stone material and a cementitious matrix binding consisting essentially of a slurry of cement, water and a plasticizing additive for cementitious slurries, wherein the plant comprises:
- A. a raw material stocking and supply section comprising a number of silos and hoppers for stocking of the inert granulated natural stone material and the cement for the preparation of a starting mixture and corresponding devices for dosing of the inert granulated natural stone materials and the cement to weighing equipment;
- B. A mixing section for preparing a cementitious matrix binding having a water content of between 0.25 and 0.36 parts by weight relative to the weight of the cement for filling voids and interstices of the inert granulated natural stone material from ingredients coming from the weighing equipment together with water and the plasticizing additive comprising a mixer for thoroughly mixing of the inert granulated natural stone material and a quantity of the cementitious matrix binding slightly in excess of a theoretical quantity of the cementitious matrix binding calculated from a void fraction of the inert granulated stone material;
- C. a section for a dosed and homogeneously uniform filling of at least one forming device with the mixture formed in the mixer to form a layer of desired thickness in the at least one forming device;
- D. a combined section for deaeration and settling of the layer in the at least one forming device comprising first vacuum generating means for subjecting a surface of the layer in the forming device to a predetermined vacuum, means for controlling and regulating the first vacuum generating means acting onto the surface of the layer and vibration generating means for applying to the layer in the forming device a vibratory motion having a frequency of between 2000 and 4800 cycles/min and for a short time but not less than for a period of at least 60 seconds, wherein the means for controlling and regulating the first vacuum generating means is adapted to cause the first vacuum generating means to generate firstly a very high vacuum not less than 40 mm Hg 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 before the vibratory motion and then to generate a vacuum lower than the previous vacuum between 70 and 80 mm Hg for a period of a few tens of seconds to about 3 minutes to provide relative settling of the particles of the inert granulated natural stone material in the deaerated layer and surface closing of the deaerated layer during the vibratory motion;
- E. a setting and initial hardening section for setting and initial hardening of the layer in the at least one forming device to form a product;
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- F. a section for removal of the product from the at least one forming device and for maintaining at rest the product for a hardening phase.
Dependencies are inferred from the claim text.