GB2175294A

GB2175294A - Production of building elements

Info

Publication number: GB2175294A
Application number: GB8512500A
Authority: GB
Inventors: Kalman Juhasz; Erzsebet Polhammer; Imre Horvath; Janos Nacsa
Original assignee: 23 SZAMU ALLAMI EPITOIPARI VAL
Current assignee: 23 SZAMU ALLAMI EPITOIPARI VAL
Priority date: 1985-05-17
Filing date: 1985-05-17
Publication date: 1986-11-26
Also published as: DE3517778A1; NL8501539A; GB8512500D0; JPS61295267A

Abstract

A process is provided for the production particularly of heat insulating building elements, in which a mixture containing fibrous vegetable matter, mainly rice-shell, binding material, e.g. cement or plaster, and water is prepared, then moulded. In the first step the vegetable matter is mixed with liquid (prewetting), which contains part of the mixing water and dissolved bond-improving agent. Dry binding material (cement or plaster), and the remaining part of the water are mixed to the prewetted material. Finally the mixture is moulded and left to solidify.

Description

SPECIFICATION Process for the production of bodies, particularly building elements The invention relates to a process for the production of bodies, particularly building elements, in the course of which fibrous vegetable matter, mainly siliceous vegetable waste is mixed with silicate-based binding material and water, then the mixture is moulded. The building elements produced according to the process of the invention are suitable primarily for solving the problems of heat-and sound-insulation, as well as those of the space delimitation.

On account of the rapid rise in the price of energy, the efficient heat insulation of buildings is more and more significant. At the same time the conventional heat insulators and technologies are generally fairly expensive, consequently their extensive use encounters difficulties, and apart from this they frequently do not meet the increasingly higher qualitative requirements.

The conventional heat insulators include the various brick-industrial products - e.g. porous stone panel which apart from their low heat insulating capacity can be used in a more and more narrow field because of the heavy weight and high demand for live labour in the production.

Heat - and sound-insulators can also be produced by swelling orfiberization of minerals (perlite, fibre-glass, rock-wool, etc.), however their production technology - including all part-processes between exploitation of the raw material and production of the end-product - is complicated and requires extremely high energy input. Further drawback is that the strength of these insulators is minimal, they become compacted during the building process, which entails reduced heat insulation capacity.

The energy demanded in the production of synthetic foams is similarly extremely high, in addition they are very expensive, generally inflammable, thus they cannot be used in large quantity.

In view of the listed drawbacks of the conventional heat insulators, the specialists endavour all over the world to develop good heat insulators and structures by using cheaper materials. Thus was the attention recently turned to the possibility of using industrial and agricultural wastes for heat insulation, since in the wake of the production concentration concomitant to the industrial development both the industrial and agricultural wastes are produced in large quantity, the extensive utilization of which is not solved, morover their annihilation is fairly costly.

In agriculture for instance some of them are burnable with difficulty, and the annihilation of the highly fibrous vegetable matter - e.g. rape, rice-straw, rice-shell - is problematic, and although several methods have been worked out for their utilization in the construction industry, so far their use in large quantity was unsuccessful.

A process for the production of heat insulating linings and bodies is described in the Hungarian patent specification No. 159 762, where rice-straw, rice-shell, or corn leaf crushings were used as basic materials, and waterglass diluted with copper sulphate solution, or two-component synthetic resin was used as binding material. The basic material - chaff- is spread over a surface and meanwhile binding material is atomized into a spray jet. Upon reaching a certain layer thickness, a layer of 50-100 mm long rice-straw is applied over the first layer, then the first step, i.e. spraying of the binding material is repeated. By repeating the two procedures as necessary, a loose layer or body is obtained which is compacted under a pressure causing moderate deformation.The drawback of this process is the complexity of the spraying technology, its demand for manual labour, and the fact that the strength is uncontrollable, it is not uniform. Apart from this, the linings orthe bodies cannot be used at all under walking surfaces, because their load bearing capacity is relatively low.

In an other process described in the Hungarian patent specification No. 181185 for the production of building element, chopped fibrous vegetable matter and fibrous material are mixed with afterhardening agent, and the mixture is moulded under pressure. Drawback of the process is that the waste as basic material has to be ground and fractioned prior to working-in, and before the binding material is added it is impregnated with material inhibiting the absorption of moisture. These activities make the process partly complicated and costly, and partly the presence of the impregnating agent prevents the perfect contact between the binding material and vegetable basic material, which adversely affects the strength of the product, thus its quality is uncertain.

The object of the invention is the realization of such process for the production of building elements suitable for heat- and sound-insulation, where vegetable waste is used as basic material without the need of physical pretreatment with complicated methods and costly technology, and/or manipulation with other methods. The process according to the invention must result in building elements suitable for heat- and sound-insulation realized either with industrial technology requiring lower expenditure than earlier, or with small-scale production methods.

The invention is based on the recognition that the favourable properties of the fibrous, particularly siliceous vegetable matter will prevail in the end-product of no physical pretreatment, e.g. fiberization is used. (The cutting of the fibrous materials for the purpose of obtaining optimal length is not regarded as pretreatment, since the basic material is not destroyed - as for instance during fiberization, carding, grinding, etc. - it is only cut through without affecting the structure of the material.) Furthermore, the main component of the highly fibrous, siliceous vegetable waste, i.e. the silicon is optimally associated with silicate-based binding materials in such a manner, that the wax-layer covering the surface of the vegetable fibres is treated with bond-improving agent.This way a highly effective contact is realized between the vegetable fibres and the binding material, which results in end-product possessing much better physical properties - including the strength -than the known building elements used for similar purpose.

On the basis of these recognitions the problem is solved with a process, in the course of which fibrous vegetable matter, particularly siliceous vegetable waste is mixed with silicate-based binding material and water, then the mixture is moulded. The essence of the invention lies in that: a./ the fibrous vegetable matter is mixed with a certain part of the water required to the binding material and allocated for the full amount of the mixture containing dissolved bond-improving agent; b./the silicate-based binding material is mixed to the obtained, prewetted fibrous vegetable matter; c./the remaining part of the water is mixed to the material simultaneously and/or following the mixing-in of the silicate-based binding material; d./ finally the mixture is moulded by conventional method, then it is left to solidify.

According to an other feature of the invention the liquid containing the mixing water and dissolved bond-improving agent and/or the second part of the water is added to the mixture without pressure suitably by spraying, which is further mixed, then moulded.

It is preferable if in the first step 1/10-1/2 part of the mixing water containing about 0.01 - 0.1 weight fraction bond-improving agent is added to 1 weight fraction fibrous vegetable matter, while in the second step 9/10 1/2 part of the water not containing bond-improving agent is added to the mixture. Generally 1-5 weight fraction cement as binding material is used for preparation of the mixture, which is added and mixed in dry condition to the prewetted fibrous vegetable matter. Naturally other silicate-based binding material, e.g.

plaster too can be used.

According to a further feature of the invention altogether about 0.2 - 3.0 weight fraction mixing water is used for preparation of the mixture. Synthetic resin-based material, e.g. polyvinyl acetate can be used as bond-improving agent.

If necessary, about 0.01-0.1 weight fraction bond-accelerator - calculated for the amount of binding material - can be added to the mixture.

In order to improve the strength and/or elasticity of the end-product, 0.01-0.1 weight fraction synthetic resin, preferablyfurfurol resin is added.

Mainly rice-shell, or rice-straw is used as basic material, but other fibrous vegetable matter e.g. cane or rape is not excluded either.

The invention is described in detail by way of examples as follows.

Example 7 60x60x5 cm partition panels are produced with the process according to the invention. For the preparation of 0.5 m3 afterhardening mixture 65 kg rice-shell is admitted into a known forced system-operated mixer (used in the concrete technology),then the machine is started. Liquid containing 45.0 kg water and 9.5 kg dissolved polyvinyl acetate is admitted to the rice-shell in motion without pressure by spraying. The stirring is continued until the mixture becomes homogeneous. This way the rice-shell is partly prewetted and partly an "adhesive-bridge" is formed on its surface, which results in a very good contact between the rice-shell and the binding material.

Then 200 lcg 350-type Portland cement as binding material is added to the prewetted rice-shell covered with bond-improving agent during its continuous stirring. When the binding material (cement) and other components are thoroughly mixed, while the mixture is continuously stirred the remaining 55 kg water required for setting of the cement is sprayed into the mixture, then about 5 kg furfurol resin is sprayed into the mixture to improve the elasticity of the end-product.

The finished, but so far not solidified mixture is moulded, the surface is flattened and the material is kept in the mould for 48 hours as required by the partial setting of the cement. This is followed by removal of the moulds, and the building panels are subjected to aftertreatment by spraying with water for 5 days.

Example 2: Heat insulating panels to be used under the floor are produced withoutcutting, with rice-straw as basic material. For the production of 0.5 m3 mixture 55 kg uncut rice-straw (about 50 cm long stalks) is put into the known forced mixer. The mass of stalks kept in motion by the mixer is mixed with liquid containing 40 kg water and 10 kg dissolved polyvinyl acetate. The mixture is stirred until the rice-straw is thoroughly wetted.

Then 200 kg 350-type Portland cement as binding material is added to the continuously stirred mixture. This is followed by spraying the remaining 45 kg water into the mixture as necessary for setting of the cement, meanwhile 5 kg furfurol resin is sprayed into the mixture.

The homogenized mixture is mouided, the thickness of which is set to 5 cm. The material is kept in the mould for 48 hours. The 60x60x5 cm panels are stored on their edges and subjected to aftertreatment by spraying with water for 5 days.

The panels can be used to advantage for heat insulation under the floor four example in single-story buildings. In this case the panels mayfulfil the function of concrete protecting the insulation against moisture. The panels produced with the process according to the invention are suitable also for the foundation under the floor.

Example 3: 60x60x6 cm panels suitable for space delimitation are produced with the process according to the invention. For preparation of 0.5 m3 mixture 45 kg rice-shell is put into the mixer and 53 kg liquid is sprayed in which contains 45 kg water and 8 kg dissolved polyvinyl acetate. Following the prewetting, 165kg plaster as binding material is admitted into the mixer which is uniformly mixed with the prewetted rice-shell. Then 75 kg water is sprayed into the mixture - that is kept in continuous movement by the mixer -, which contains 5 kg carboxymethyl cellulose (CMC) as bond-delaying agent. The mixing with the second part of the water is continued for 3 minutes, then the wet, not solidified mixture is poured into the mould laid to one of its wide sides and its surface is flattened.

Mould standing on its edge can also be used, both large sides of which are flat, and the material is poured in on the top; thus the smoothness and uniformity of the element surfaces can be easily accomplished.

The mixture is kept in the mould for about 10 minutes; during which it sets to such degree that it can be stored without the mould and dried until its air-dry condition is reached. The finished elements can be used for example as partition walls.

The following table contains informatory data about the parameters of the building elements made of the same basic material, but with two types of binding material according to the process of the invention: Building elemental Building element II Basic material: rice-shell rice-shell Binding material: cement plaster Bond-improving polyvinyl acetate polyvinyl acetate agent Volume weight: about 700 kg/m3 about 950 kg/m3 at -100C 0.116 at-10 C0.196 Thermal con- at +10 C 0.121 at +10 C 0.221 ductivity: at +30 C 0.126 at +30 C 0.245 Constancy of volume: 0.999 0.999 Burnability: non burnable non burnable The main advantage of the invention is that it enables the application of agricultural wastes, the annihilation of which is difficult and costly, such as rice-shell as basic material for the extremely rational production of building elements. Namely there is no need to subject the basic material to physical or chemical pretreatment (e.g. fiberization, crushing, impregnation, etc.) - requiring separate technological step, which is beneficial not only in respect of economic efficiency, but it favourably influences the quality of the end-product, since the required favourable properties of the fibrous vegetable matter will best prevail if their structure remains intact.The synthetic resin-based bond-improving agent - as a result of which the satisfactory contact between the basic material possessing waxy surface and the binding material is adequately ensured - is admitted in a small quantity into the technological process together with the water of the binding mateial in which it is dissolved, without the need of special measures and equipment, costly technological operations, heat treatment, pressure, etc.

Moulding of the raw mixture to a body does not require special compaction, the elements can be produced by methods and moulds used in the concrete technology. Either panel or block type elements for the most diversified purposes can be produced suitable for the erection of walls, partitions and ceilings.

Since the building elements possess good heat insulating properties, they can be used for subsequent heat insulation, as well as for the heat insulation of walls, foundations, ceilings, false ceilings, and for elimination of thermal bridges, etc. Their use is advantageous in special construction processes as permanentformwork. With concrete poured between permanent form panels, wall structures of adequate strength and good heat insulation capacity can be built. (The volume weight of the elements may be between 400 and 1000 kg/m3, thermal conductivity about 0.12 W/m3K.) There is no need to fix the heat insulating panels produced according to the invention to a concrete body with additional fixing elements, because they bond well to the concrete as a result of the structure and surface of the material.Such panels can be fixed with cement-gel in a simple way to the existing concrete walls.

The wall made of building blocks made according to the invention - e.g. in case of residential buildings meets the strictest power engineering specifications even in case of 20 cm wall thickness.

One of the preferable application methods of the panel-type products of the invention is to build them into the groundfloor of the buildings, where they form heat insulating layer, at the same time - because of their water insulation -they replace the concrete foundation. Thus simultaneously along the reduced concreting work on the site, the power engineering properties of the floors will be considerably improved.

Working of the elements is simple, since they can be sawn, carved, nailed. Insects, fungi do not damage the material, and it is not burnable.

With the building elements produced according to the invention, the space delimitation and heat insulation system of complete building e.g. agricultural buildings can be accomplished.

The raw mixture can be prepared either with mechanical or manual mixing. The elements can be produced equally with small-scale, domestic or industrial methods.

The invention has particularly economical and extensive application potentiality in the rice-growing areas, where the availability of wood is generally limited and not durable either, while the rice-shell, rice-straw are available in large quantity, which according to the process of the invention can be processed as building elements either naturally or with industrial methods.

The volume weight, strength, solidity and other properties of the produced elements can be improved with synthetic resins, light or heavy supplementary materials , additives. Besides known chemicals, e.g.

"TRiCOSAL", heat treatment, preferably steaming too can be used as bond-accelerator.

Naturally the invention is not restricted to the quoted examples, but it is realizable in many ways within the scope of the claims.

Claims

1. Process for the production of bodies, particularly building elements, in the course of which fibrous vegetable matter, mainly siliceous vegetable waste is mixed with silicate-based binding material and water, then the mixture is moulded, characterized in that a./ the fibrous vegetable matter is mixed with part of the water needed to make the panel and which also contains dissolved bond-improving agent required for bonding to the binding material; b./ the prewetted fibrous vegetable matter is mixed with the silicate-based binding material; c./ the remaining part of the water is mixed with the material simultaneously with and/or following the mixing-in of the silicate-based binding material; d./ finally the mixture is moulded, then left to solidify.

2. Process as claimed in claim 1, characterized in that the liquid consisting of water and dissolved bond-improving agent, and/or the second part of the water are sprayed into the mixture without pressure, then stirred further and moulded.

3. Process as claimed in claim 1 or 2, characterized in that in the first step 1/10-1/2 of the total water containing about 0.01-0.2, e.g. 0.01-0.1 parts by weight bond-improving agent is used, then in the second sten 9/10-1/2 of the water without any bond-improving agent is added to 1 weight part fibrous vegetable matter.

4. Process as claimed in claim 3, characterized in that 1 to 5 weight parts cement as binding material is used for preparation of the mixture, which is added in dry condition to the prewetted fibrous vegetable matter and mixed with it.

5. Process as claimed in claim 3 or 4, characterized in that about 0.2-3.0 weight parts mixing water is used for preparation of the mixture.

6. Process as claimed in any of claims 1 to 5, characterized in that synthetic resin-based material, preferably polyvinyl acetate is used as bond-improving agent for preparation of the mixture.

7. Process as claimed in any of claims 1 - 6, characterized in that about 0.01-0.1 weight parts bond-accelerator calculated on the quantity of the binding material is added to the mixture.

8. Process as claimed in any of claims 1 to 7, characterized in that in order to improve the strength and/or elasticity of the end-product, 0.01-0.1 weight parts synthetic resin, preferablyfurfurol-resin is added to the mixture.

9. Process as claimed in any of claims 1 to 8, characterized in that rice-shell and/or rice-straw, and/or rape, and/or cane is/are used as fibrous vegetable basic material.

10. Process as claimed in any of claims 1 to 3, and 5 to 9, characterized in that plaster as binding material and in given case bond-delaying agent are added to the mixture.

11. A process as claimed in claim 1 substantially as hereinbefore described in any one of Examples 1 to 3.

12. Process as claimed in claim 11, wherein bond-delaying agent is added to the mixture.

12. A building element whenever made by a process as claimed in any one of claims 1 to 11.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1 to 10 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: (c) Claims 11 and 12 above have been re-numbered as 13 and 14 and their appendancies corrected.

1. Process for the production of bodies, particularly, building elements, in the course of which fibrous vegetable matter having a waxy surface is mixed with silicate-based binding material and sufficient water to cause the building material to set, the process comprising the steps of: (a) mixing the fibrous vegetable matter with part of the water needed to make the panel and which also contains dissolved synthetic resin-based bond-improving agent for bonding to the binding material; (b) mixing the prewetted fibrous vegetable matter with the silicate-based binding material; (c) mixing the remaining part of the water with the material simultaneously with and/orfollowing the mixing-in of the silicate-based binding material; and (d) finally pouring the mixture into a mould and then ailowing it to solidify.

2. Process as claimed in claim 1, wherein the bond improving agent is polyvinyl acetate orfurfurol resin.

3. Process as claimed in 1 or claim 2, wherein the liquid consisting of water and dissolved bond-improving agent, and/orthe remaining part of the water are sprayed into the mixture without pressure, then stirred further before moulding.

4. Process as claimed in any one of claims 1 to 3 wherein in step (a), 1/10-1/2 of the total water containing 0.01-0.2 parts by weight bond-improving agent is used, then in step (c), 9/10-1/2 of the water without any bond-improving agent is added to 1 part by weight fibrous vegetable matter.

5. A process as claimed in claim 4, wherein the water added in step (a) contains 0.01 to 0.1 parts by weight of bond-improving agent.

6. Process as claimed in claim 5 wherein 1 to 5 parts by weight cement is used as binding material for preparation of the mixture, which is added in dry condition to the prewetted fibrous vegetable matter and mixed with it.

7. Process as claimed in any one of claims 4 to 6, characterized in that about 0.2-3.0 parts by weight mixing water is used for preparation of the mixture.

8. Process as claimed in any one of claims 1 to 7, wherein 0.01-0.1 parts by weight bond-accelerator calculated on the quantity of the binding material is added to the mixture.

9. Process as claimed in any of claims 1 to 8, characterized in that in order to improve the strength and/or elasticity of the end-product, 0.01-0.1 parts by weight of bond improving agent is used.

10. Process as claimed in any of claims 1 to 9 wherein the fibrous vegetable matter is rice-husks and/or rice-straw, and/or rape, and/or cane.

11. Process as claimed in any one of claims 1 to 5 or any one of claims 7 to 10, wherein the binding material is plaster.