A METHOD FOR THE MANUFACTURE OF INSULATING, POROUS, SHAPED ARTICLES AND WALLS AND PARTS OF BUILDINGS, MADE WITH SUCH ARTICLES

Abstract: A method for the manufacture of insulating, porous shaped articles wherein porous filling bodies are provided with an outer coating of a tacky substance, subsequently made tack-free by the addition of a powdery substance, whereupon the discrete particles thus obtained are mixed with a hardening binder, whereafter the mass is transferred into a mould or formwork. Optionally a foaming agent and waterglass may be added. The powdery substance is suitably cement. The foaming agent is preferably a protein-concentrate.

Description: A method for the manufacture of insulating, porous, shaped articles and walls and parts of buildings, made with such articles. The invention relates to a method for the manufacture of insulating, porous, shaped articles and buildings and/or parts of buildings, made with such articles.More in particular the invention relates to a method for the manufacture of insulating, porous, shaped articles, such as flat plates, blocks or similar construction elements, which may be provided with chan¬ nels or hollow areas. It is known from Dutch Patent Application No. 7113658 to manufacture porous, shaped articles using expanded polystyrene spheres, provided with a coating consisting of bituminous or tar-like products, which have been applied on the surface of the sphere, and wherein cement and/or sand paricles are incorporated completely or partially, thus obviating the tackiness ' of the bitumninous or tar-like product, whereafter these spheres are combined with each other by addition of cement or cement/sand mixtures and water, whereby this mass solidifies in a mould to s-haped articles. An improvement of said method is described in European Patent Specification No.0031365, whereby the odour of the bitumen or tar is avoided and the strength of the shaped article is increased by using a mixture of bituminous or tar-like products and waterglass, wherein the amount of waterglass may constitute up to 75% of the mixture. he shaped articles thus obtained exhibit good insulating properties and are heat- and • moisture resistant. However, the shaped articles have the disadvant- age that the bonded spheres will release from the shaped article by mechanical powers, which are for example the result of transportation and handling at the building- site as well as screwing and nailing, which may result in undesired modification of shape and weak spots in the articles. The present invention now has as an object to provide an improvement of this known method, whereby the product not only shows the advantages of the pro¬ ducts already known, but is also easier nailable and screwable and can be worked with customary hand-tools without bonded spheres releasing from the binder. Moreover the weight per unit of volume and the com- pressive strength may be adjusted as desired. The invention provides to that end a method for the manufacture if insulating, porous, shaped articles such as flat plates, blocks and other shaped articles, such as walls, floors or pre-shaped elements for buil- dings, which optionally may be provided with channels and or hollow areas, wherein hollow or partially hollow articles, such as polystyrene spheres, hollow spheres of glass or plastic, porous particles of ceramic mate¬ rial and other porous filling bodies are provided with an outer coating, consisting of a tacky substance, which adheres to the surface of the filling bodies, such as. bituminous and tar-like products, resinous products, such as paint binders on a basis of natural or synthetic resins or polymers in initial state or in diluted or dissolved form or in the form of dispersions or emul¬ sions in water or other non-solvents for that. The tacky layer may also be applied as a mixture of the tar-like_ or bituminous or resinous products or polymers with a solution of soluble silicates, wherein the amount of silicate solution may amount up to 75%. The tacky layer is dusted by addition of powdery or finely granulated substances, for example cement, - lime, chalk, sand, talc, gypsum and other substances which do not interfere with the hardening of the binder later on, so that a mass is formed, consisting substan¬ tially of separate, coated spheres. The coated spheres, thus obtained, are mixed with a binder, which may consist of material which in the course of time will harden by chemical or physical processes, such as mixtures of water with cement, gyp- sum, lime, sand, clay or mixtures thereof, or by resins or plastics of natural or synthetic type or mixtures, thereof with earlier mentioned binders, such as mixtu¬ res of sand and emulsions of polyvinylacetate, rubbers or solutions or emulsions of resins or polymers, which by drying or evaporation of the solvent, whether or not in combination with chemical reactions, form a mass that keeps in shape. The binders mentioned may be added both in mas¬ sive form as well as in foamed or beaten up form or volume increasing and weight lowering additives may be added thereto. The mixture of filling bodies and binder thus obtained is shaped to the desired articles by transfer of the not yet hardened mass into a mould and allowing this mass to harden or to harden partially, so that the articles can be released from the mould and can harden subsequently in free space.The mass may also be applied in unhardened state and be hardened at the eventual place of use.During the application of the unhardened mass into the mould or at the eventual place of use vibrating or shaking treatments may be applied or the mass may be transferred under pressure in order to obtain a better homogeneity of the eventual moulding piece. The articles obtained in this manner achieve a 2 compressive strength of at least 10 kg/cm and prefera- 2 bly at least 40 kg/cm , while the articles may be very resistant to fire, depending on the type of the binder. For a proper selection of the amounts and types of raw materials shaped articles can be obtained with this method, which have such a compressive strength, that they are suitable as supporting elements or filling _ A _ elements in buildings and for the construction of floors or floor elements. By a proper selection of ground materials it is thus possible to manufacture articles or bodies in this manner, which can be worked excellently with" usual tools. If desired the articles which have been obtained after compression and vibration movements may be put to dry in self-supporting condition, without the necessity to keep them locked in moulds such as is the case for articles obtained according to the method described in European Patent Specification No.0031365. In the method according to the invention the compression and/or vibration treatment may be carried out in an apparatus of the type "Hydramat" as supplied by "Hess Maschinenfabrik KG" for compressing customary non-porous concrete blocks, the compressive force while carrying out the method according to the invention being substantially lower than the compressive force required for compressing customary concrete blocks. The tacky binder applied to the porous particles may be composed of a bituminous or tar-like product but also of other tacky substances such as solutions, sus¬ pensions or emulsions of polymers or resins of natural or synthetic origin.Some examples are solutions of shellac in alcohol, emulsions of polyvinylacetate, which are used in the manufacture of latex-paint solu¬ tions of natural and synthetic resins, as are used in the preparation of paints and varnishes, as well as the paints and varnishes themselves, in as far as- they do not affect the porous articles or only to a very limit¬ ed extent. In some cases aqueous solutions of plastics or natural products may act as tacky binder as well. The binder may also be blended with a solution of soluble silicates of metals of the first main group of the periodic system, preferably a solution of sodium or potassium silicate, as these are known under the name waterglass, wherein the amount of waterglass may be up to 75 % of the weight of the total mixture with the tacky binder. The powdery substance is preferably added at the end of the blending operation whereby the powder ' particles will adhere to the tacky binder and thus will form a layer on the surface of the porous part¬ icles.Preferably use is made of a powdery substance which later on will also be applied in the hardening binder, but it is quite well possible to use another type of powdery substance in this manner. The hardening binder may be added completely or partially during the first blending or may be added completely or partially after the first blend¬ ing.If required the hardening binder may be pre-mixed with water and possibly other additives such as foam¬ ing agents, stabilizers, dyes, promotors, retardants, and other components such as known from the process- ing of concrete and which are required to achieve the desired properties of the hardening binder. As foaning agent a proteinaceous concentrate, such as available from the firm SK at Trostberg, may be used, while the concentrate may be added in concen- trated or diluted form, but other customary foaming agents and surface active compounds may be used as well, apart from foaming or beaten up resins. he addi¬ tion may be carried out with known dosing apparatus. The invention will now be elucidated in more detail starting from one of the possible formulations in this case on the basis of coated spheres of expand¬ ed polystyrene foam, wherein the coating consists of a bituminous product, waterglass and cement, whereas the hardening binder consists of a mixture of foamed concrete. However, it is quite well possible to manufac¬ ture other systems according to the principle of the discovery wherein earlier mentioned components do not occur at all. The invention will now be elucidated in more detail by means of the accompanying drawing. Example In a silo (1) expanded spheres of foam material made in a known manner, are stored. hese may consist for example of polystyrene. hese spheres may have a diameter of 0.5 to 15 mm, more in particular a diame- ter of 3 to 5 mm and a specific weight of 10 to 15 kg per cubic meter.At the lower side of the converging lower end (2) of the silo is a small rectangular dis¬ charge opening, under which a helical screw conveyor is present in a cylindrical housing (3) , directly connected with said discharge opening, the conveyor being driven by an electromotor, which either as such or of which a transmission driving gear is gradually variable in number of revolutions within a broad range of velocities from standstill, in order to drive the helical screw conveyor with a variable, accurately adjustable velocity.The helical screw conveyor emerges into a suction-duct (4) of an exhauster (5) , of which the blade-wheel has rounded off blades, allowing the spheres to pass without being damaged. he exhauster (5) blows the spheres through a conduit (6) towards a silo (7) , provided with a suitable air outlet, for example a fine-meshed sieve plate, mounted in the upper side, so that the air coming from the exhauster can escape readily. The spheres fall from silo (7) into a first compounding mill (8) , consisting preferably of a trough with two horizontal shafts, running parallel to each other, each provided with radially extending pins, which are each time displaced with respect to adjacent pins somewhat in the direction of the circum¬ ference, so that their free ends show a helical course around the shaft.Compounding mill (8) has for example a length of 4 meters and the mutual distances of the pins on each shaft are for example 10 cm.The pins on the two shafts overlap each other so that on rotation of the shafts in opposite direction the pins will pass each other at short distance and the pins in ' the area between the shafts will move in a downward direction ' . The ends of the pins will move close to the wall of the trough of compounding mill (8) .The pins occupy about three threads around the shaft.Similar compound- ing mills are known in essence. he shafts rotate with a velocity of at most 200 rotations per hour.A supply apparatus for the tacky substances or a mixture of the tacky substance and the solution of the soluble sili¬ cate emerges at about 90 cm from the discharge opening of silo (7), delivering in an accurately dosed manner a quantity of the tacky substance to the porous parti¬ cles in compounder (8) .Compounding takes place over a part of the path in compounder (8) , whereafter an amount of powdery substance is brought into the co - pounding mill from a bunker (13) at (12) by means of a cell-wheel.Shortly before the addition of the powdery substance the porous particles tightly adhere to each other by the tacky substance or a mixture of the tacky substance and the soluble silicate, which is at the surface of the particles.The addition of the tacky sub¬ stance or the mixture of tacky substance and the solu¬ tion of the silicate may occur at increased temperatu¬ res. After addition of the powdery substance to the agglomerated particles a mass of separate spheres is obtained again at a short distance in the compounder ' nehind the supply point of the powdery substance.The total residence time of the spheres in the compounder (8) amounts to 2 to 6 minutes, with in the initial 3 meters only porous particles and the tacky liquid or a mixture thereof with the soluble silicate being mixed in the compounder and in the last meter of the com- pounder (8) the powdery substances being present as well. The pins (10) on shafts (9) do not or hardly provide any conveyance themselves in axial direction of the compounder (8) .The conveyance thus takes place mainly by displacement of the material present in the compounder by freshly supplied material.As the spheres clot together the powdery substance can not or hardly reach the spheres which have not yet been mixed adequately_with the tacky substance by flowing upstream At the discharge opening of the compounder (8) the hardening binder, in this example cement, is added from a hopper (15) at (14) at the beginning of a conveyor belt (16) .Cell-wheels may be used at (12) and (14).Belt (16) conveys the porous particles, in this example polystyrene foam spheres, to a secon compound¬ ing mill (17) , which has the same construction as compounder (8) , but may be shorter than the latter, for example 3 meters and with pins covering 2\ threads.At a short distance from the inlet water and in this example a proteinaceous foaming agent are added therein from belt (16) at (18), preferably divided over a num¬ ber of points over the length of mill (17), for example over a length of 1 meter.The water and as in this exam- pie the foaming agent may be added both together or separately by means of a proportioning apparatus, pre¬ ferably a pump. The mixture leaves the mill (17) at (19), where it is poured or pumped into moulds.It is then dried in the mould or formwork.After adequate hardening or stif¬ fening the mould may be removed already prior to com¬ plete hardening, whereafter the formed piece is dried further. A mixture as meant in the example described above may consist of 20 kg polystyrene foam spheres with dimensions as described, about 6 kg tacky substan¬ ce, or for example 5 kg tacky substance and 10 kg of waterglass, 50 kg powdery substance such as cement or a mixture of sand and cement, 50 kg hardening binder for example cement, 45 kg water and in this example about 3 kg of protein-concentrate as foaming agent. The powdery substance and the hardening binder may consist of different compounds but may also consist of the same compound. Additives may also be added to the hardening binder so as for example sand, pebbles and other par- tides, which increase the volume.

Claims: Claims : 1. A method for the manufacture of insulating, porous articles, such as flat insulation plates, pro¬ vided with channels, blocks and similar shaped pieces, characterized in that the porous particles are coated in advance with a tacky liquid, or a mix¬ ture thereof with a solution of a silicate, which are subsequently made tack—free by the addition of a pow¬ dery or granular substance, whereby the mass consists again of separate particles, which are completely or partially coated with the above-mentioned tacky sub¬ stance, or a mixture thereof with a solution of a sol¬ uble silicate, and at the exterior thereof with a pow¬ dery substance, whereby the porous particle is connec¬ ted with the powdery substance by the tacky substance, whereafter these particles are mixed with a hardening binder, whereafter the mass is transferred into a mould or formwork, so that after hardening in a mould or formwork a form piece is obtained of the desired - shape. 2. A method according to claim 1, characterized in that the tacky substance consists of a liquid polymer or solid polymer or resin of natural or synthetic ori¬ gin or a solution, emulsion or dispersion thereof or of a tar-like or bituminous product in undiluted form or in the form of a solution, emulsion or dispersion thereof_ 3. A method according to claim 1 or 2 , characteri- zed in that the powdery substance consists of cement, gypsum, clay, talc, chalk, stonepowder and similar water insoluble powders or granular substances with a particle size of less than 0.5 cm. 4. A method according to claims 1-3, characterized in that the hardening binder consists of inorganic compounds, compounded with water, such as cement, gypsum, lime, chalk or mixtures thereof. 5. A method according to claim 1-4, characterized in that one or more additives are added to the harden¬ ing binder, such as foaming agents, hardeners, accel¬ erators, retarders, dyes and inert supplements such as sand, pebbles, glass and other fillers, which increase the volume. 6. A method according to claim 1-5, characterized in that a quantity of watersoluble silicate is added in addition to the tacky substance as referred to in claim 2, the amount of solution of silicate being at most 75% by weight of the mixture. 7. A method according to claim 1-6, characterized- in that polystyrene . foam spheres are used as porous particles with a diameter of 0.5 to 15 mm, preferably 3 to 5 mm with a specific weight of 5 to 100 kg per cubic meter, preferably 10 to 12 kg per cubic meter. 8. A method according to claim 1-6, characterized in that a shaking or vibrating action is applied during filling of the moulds for better filling of the moulds. 9. A method according to claim 1-7, characterized in that a protein-concentrate is used as a foaming agent as mentioned in claim 5, in an amount of 0.1 to 5% by weight, based on the total weight of solid components of the ultimate mixture. 10. A method according to claim 8, characterized in that about 6 kg tacky substance or 5 kg tacky substance and 10 kg waterglass, in addition 50 kg of sand, 50 kg of cement, 45 kg of water and 3 kg of protein-concen¬ trate are added per 20 kg of foam spheres.

Inventors: LAAN DIRK, LAAN, DIRK
Applicants: STICHTING IWL
Application year: 1985
Main classification: C04B28
IPC codes: C04B26, C04B28, C04B38