DE2532423A1 - PROCESS FOR MANUFACTURING WATERPROOF PRE-FABRICATED COMPONENTS - Google Patents

Description

Dipl.-Ing. H. Sauerir? Nci · Dr.-Ing. R. König ■ Dipl.-Ing. K. Bergen

Patent attorneys ■ 4ooo Düsseldorf 3D ■ Cecilienallee ve ■ Telephone 433732

July 18, 1975 30 156 K

James Neville Lowe, Quarry Hill House, 48 Gatton Road,

Reigate , Surrey (UK)

Byron Calvin Grebe, 3981 Glendale Drive,

Memphis , Tennessee 38128 (V.St.A.)

"Process for the production of waterproof prefabricated components"

The invention relates to a method for producing waterproof prefabricated components, in which a plaster of paris containing moist casting compound is poured into a mold and cures there under the influence of the heat of reaction.

Processes of the aforementioned type for the production of prefabricated components are known and are based on the use of partially water-free gypsum with the chemical formula CaSO ^. 1/2 H ₂ O instead of Portland cement as a binder. The plaster of paris can be burned in an autoclave under normal conditions or with a view to greater strength. The use of burnt gypsum as a binding agent has the great advantage that the cast prefabricated component achieves sufficient green strength for demoulding much more quickly than when using Portland cement or mortar can be handled and transported after just a few hours. This has the particular advantage of a high degree of utilization of the forms and a low space requirement. Nonetheless, the endeavor goes

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to increase productivity even further in order to reduce costs.

Since calcined plaster of paris is still water-soluble to some extent after it has set, calcined plaster of paris come with them Prefabricated components for passages which are exposed to the influence of the weather or for purposes in which they are are acted upon with steam, out of the question “Although are Numerous attempts have already been made to provide such prefabricated components with a waterproof surface «, The considerations were always based on providing the surface with a continuous waterproof coating, but without leading to success.

The invention is therefore based on the object of a method for producing prefabricated components containing plaster of paris with a waterproof surface without creating a continuous coating «The solution to this problem is based on the realization that it is not necessary to provide the component surface with a continuous coating in order to to achieve sufficient water resistance. Rather, it is sufficient to use the capillary effect known from plaster of paris components to be used while the casting compound is still moist in order to suck a sealant into the component surface and to make the component waterproof in this way «,

In particular, the invention consists in a method in which a plaster of paris containing plaster of paris moistened with water Casting compound is poured into a mold and cures there under the influence of the heat of reaction, according to the invention the surface of the still warm and damp prefabricated component treated with a water-hardening synthetic resin that expands as it hardens and by capillary action is sucked into the mass of the prefabricated component and hardens there, in order to create the surface pores

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to be filled in and sealed.

Polyurethane resin is particularly suitable for sealing the prefabricated component, albeit any other water-hardening and Resin swelling during hardening comes into question, for example Synthetic resins based on soybean oil.

The liquid sealing agent or resin is preferably shortly before or immediately after demolding on the Component surface applied while the component mass is still under the influence of heat from the exothermic Reaction of the plaster of paris with the water. The heat of reaction contributes in this way to a rapid Hardening of the synthetic resin, so that the resin impregnating the surface to some extent during hardening is burned.

The process according to the invention is advantageously used together with another new process in which the mass is warmed up before casting and then brought to a temperature of 32 to 82 ^° C. by the heat of reaction.

Furthermore, in this process, the binding agent consists of a mixture of 10 to 9096 gypsum and 90 to 10% Portland cement. In order to harden the cement part and a significantly higher compressive strength than when using fired To achieve plaster of paris alone, the component is tempered after demoulding at a temperature of 32 to 82 ° C. and humidity-controlled cooled to the temperature and humidity a certain time of at least two, preferably held up for three hours to allow the cement to set. During this time, this also hardens on the component surface applied impregnating resin, so that after hardening the component surface is already waterproof is.

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After setting of the Portland cement, the component is either dried in flowing air or in a vacuum, although the moisture can escape in view of the surface coating only unsealed surface zones _o This has the particular advantage, in that the moisture required for the setting of the cement substantially easier to set and maintain. If, for example, an L-shaped component is cast, one leg of which is twice as thick as the other leg, one surface of the thinner leg can be made waterproof with the method according to the invention, so that during the subsequent drying the moisture over both surfaces of the thicker leg , but can only escape over a surface of the thinner leg. In this way, a uniform dehumidification of both legs of the component can be achieved. In this way, internal stresses can be avoided and the risk of cracks forming as a result of uneven drying can be significantly reduced.

The invention is explained in more detail below using an exemplary embodiment and the drawing. In the Drawing show:

1 shows a schematic representation of a system for producing wall elements and

FIG. 2 partial views of the system according to FIG. 1 for a more detailed explanation of the workflow.

The system consists of a mixer 1 with two counter-rotating mixing blades and a hopper 2 for the mix, a water pipe 3 is provided with a heater 4 and opens into the hopper 2. The mixer is Provided with a flexible filling pipe 5 via a tap 6.

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Next to the mixer 1 there is a pivotable pouring table 7, which consists of a horizontal position shown in FIG. 2a can be pivoted into a vertical position shown in FIG. 2b. The casting table 7 contains a mold 8 for producing a wall element 9 with five parallel stiffening ribs 10.

On the opposite side of the pouring table 7 from the mixer 1 there is a dryer 11 with thermally insulated and moisture-proof walls 12 and individual chambers 13. The chambers 13 are through at their end faces walls corresponding to the walls 12 and closed at the top by a removable cover 14. All walls 12 and the lid has a core made of foamed polystyrene as a thermal insulation, the one with polyethylene as a vapor barrier is coated. In addition, the walls 12 are provided at regular intervals with steel supports on which cross beams of the cover 14 rest. A blower 15 supplies air to a manifold 16, each of which branches off to the bottom Chamber 13 of dryer 11 lead. A bridge crane 17 for transporting the wall elements can be moved on rails 18 and spans the casting table 7 and the dryer 11.

The mass for manufacturing the wall element is composed as follows:

Plaster of paris fired in an autoclave 23 kg

finely ground sulfate resistant

Cement 23 kg

Superplasticizer (melment or rubber

Arabic 0.14 kg

Sisal fiber 0.23 kg

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Foaming agent (sodium) .auryl-

SuIfonat) 0.23 kg

Retardant (sodium

Citrate) 0.023 kg

Wax resin (in-water emulsion) 0.45 kg Water 17.2 kg

Mixing takes place according to the following schedule:

· 9O96 of the water will be in the mixer given;

2. the sodium citrate is dissolved in the water;

3. the mixer is operated at 40 rpm and 9096 of the dry mix are added;

4. thorough mixing; 1 min,

5. the foaming agent and the remaining IO96 of the water are poured;

6 _e the stirring speed is increased to 55 rpm for 30 seconds; 1.5 min,

7. The remaining 10% of the dry matter is stirred for a further three minutes put in the mixer; 4.5 min,

8. the mixture is poured into the downcomer 5 in

given the shape 8; 5 min.

9. the temperature of the potted mass

rises; 45 min. \

10. the casting table is swiveled into the vertical and the wall element is removed. 46 min.

If the wall element is intended for a higher load

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is, it receives a reinforcement in the form of a reinforcement mat 19, which is usually placed in the mold 8 The mat 19 has an eyelet 20, or in the case of a wall element without reinforcement, an eyelet hook is used cast in the wall element.

After the casting table 7 has been swiveled up, the wall element is removed with the aid of the dryer cover attached to the crane 17 14 taken out of the mold.

The casting table is then swiveled back to the horizontal and is then ready for casting the next wall element, while the preceding wall element is placed on the ground and held in a vertical position by the crane will.

The later outer surface of the wall element, in the present case the left surface in Fig. 2b, is then with sprayed with the polyurethane resin, although this can also happen while the wall element is after casting is still in shape. The sprayed-on polyurethane resin is under the influence of capillary action in the warm and the moist mass is sucked to a depth of about 6 mm. The spraying is continued for as long as the Solution is absorbed. Experiments have shown that an application rate of about 1 l / m is normally sufficient, although in many cases a less complete seal with an application amount of 0.1 l / m is sufficient.

Immediately after the liquid polyurethane resin has been sprayed on, the wall element is placed in one of the chambers of the dryer 11 brought and the dryer closed with the lid 14. The further course of the exothermic reaction of the baked plaster of paris with the water leads to a temperature

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increase and to maintain the elevated temperature in view of the heat-insulating chamber walls 12. The relative The humidity of the chamber atmosphere increases to 100%, so that the cement content of the mixture in the hot humid atmosphere sets quickly. During this phase, the chamber temperature is 60 to 82 ° C and is usually around 70 ° C. Curing takes three to five hours or sometimes longer, with the hot humid atmosphere extremely favorable for rapid hardening of the liquid resin located in the pores of the surface of the component is. When hardening, the resin expands and gives the surface sufficient water resistance.

As soon as the cement has sufficiently set and the polyurethane resin has hardened, the fan 15 is switched on and air is blown into the chamber containing the wall element 9. Under the influence of the air and the residual heat of the humidity of the wall element is evaporated to a moisture content of 2 to 10 wt% _e. After two to three hours of air drying, the wall element is taken out of the dryer and then already has sufficient transport strength. Instead of using air, the wall element can also be dried by applying a vacuum to the non-impregnated surface. In this way, the moisture content is sufficiently reduced within a few minutes

Should the component surface, unless it is impregnated has been made water resistant with polyurethane or another synthetic resin, for example with a Paint, then the surfaces are preferably first partially after drying with a Acrylic latex emulsion sealed. This emulsion seals unlike the hardening synthetic resin, the pores of the surface are not completely and allow the surface to breathe, so

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that the moisture content can adjust the device on the corresponding area automatically and can not build up of water vapor pressure in the pores _s as would be the case if the entire surface had been made waterproof.

The surface is partially covered with an acrylic latex emulsion provided, then the prefabricated component is preferably dried in a vacuum and is still like this after vacuum drying warm that a quick drying of the acrylic latex emulsion results.

The casting compound and / or the polyurethane resin or another resin for surface treatment can also be with a
Be provided with dye «,

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Claims (1)

James Neville Lowe, Quarry Hill House, 48 Gatton Road, Reigate , Surrey (UK) Byron Calvin Grebe, 3981 Glendale Drive, Memphis , Tennessee 38128 (V ₀ St.A.) Claims; (1, y / method for manufacturing waterproof prefabricated components, at which a moist casting compound containing plaster of paris is brought into a mold and there under the influence of the heat of reaction hardens, characterized in that at least part of the still A water-hardening synthetic resin that expands when it hardens is applied to the warm and damp prefabricated component will. 2. The method according to claim 1, characterized in that that a polyurethane resin is applied. 3. The method according to claim 1 or 2, characterized in that the resin is still during the Reaction of the plaster of paris with the water being applied. 4. The method according to one or more of claims 1 to 3, characterized in that the Resin applied immediately before or after demolding at a component temperature of 30 to 85 ° C and the temperature and moisture is maintained for at least two hours. 5. The method according to one or more of claims 1 to 4, 609809/0678 characterized in that the component is thermally insulated and moisture-proof Chamber is held. Method according to one or more of Claims 1 to 5, characterized in that the Binder 10 to 90 # plaster of paris and 90 to 10% Portland cement contains. 7. The method according to one or more of claims 1 to 6, characterized in that on an acrylic latex emulsion is applied to a non-impregnated part of the component surface after drying. 8, method according to one or more of claims 1 to 7, characterized in that the component after holding the temperature for at least two hours and moisture dried in vacuo and the acrylic latex emulsion immediately after drying on the the component is still warm. 609809 / 067R