DE2418354A1 - PROCESS FOR MANUFACTURING PRE-CASTED CONCRETE SLABS WITH A SURFACE LAYER - Google Patents

Description

DR.-ING. VON ^ Rf-ISLEP DR.-ING, SCHÖNWALD DR.-ING. TH. MEYER DR. FUES DIPL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLÖPSCH DIPL.-ING. SELTING

5 COLOGNE 1, DEICHMANNHAUS

Cologne, April 16, 1974 AvK / Ax / IM

Nippon Paint Co., Ltd., No. 1-1, Oyodo-cho Kita 2-chome, Oyodo-ku, Osaka-shi, Osaka-fu / Japan Taisei Prefab Corporation, No. 22-17, Nishigotanda 7-chome, Shinagawa-ku, Tokyo-to / Japan

Process for the production of precast concrete slabs

with surface layer

The invention relates to the manufacture of precast concrete slabs (hereinafter referred to as "VB" slabs) which are provided with a surface layer, according to a process in which the manufacture of the VB board and the surface coating take place simultaneously on a single production line.

So far the. Surface of VB panels coated by Resin paints or cement-based sprays have been applied to the surface of the VB panels. When using paints on synthetic resin bases, they are usually applied after the pH value has been lowered or the water content of the surface of the VB board. The surface of a VB board shows the beginning of hardening a pH of 11 to 12, while a favorable pH for application is 9 or below. as well is a water content of the VB board of 10% or less for the order, which decreases with the lowering of the pH value he wishes. It usually takes several weeks before the coating can be applied. at The use of cement spray, on the other hand, can be applied without such a lowering of the pH value or the water content the VB disk can be made, but the disk

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must be left to harden for a long time (e.g. about 1 month) in order to achieve sufficient strength of the applied layer. As a result, the coating is necessary to be carried out separately from the manufacture of the VB panels. Generally this happens after hardening the VB panels or after completion of the building. The simultaneous surface coating in a single Production line for the manufacture of VB panels has never been implemented.

It has now been found that the surface coating of VB panels with a high water content is carried out properly can be used if a flowable mass is used, which as a base material a hydraulic cement or a Contains alkali silicate or a colloidal silica sol. The invention is based on this finding.

The object of the invention is accordingly the production of precast concrete slabs, which are provided with a surface layer, by a method which is characterized in that a concrete mass is poured into a frame and the concrete mass obtained hardens and a "flowable mass, which is a hydraulic cement or an alkali silicate or a colloidal silica sol as a base material, applies to the surface of the concrete mass, this application in cases in which the hardening takes place under heating, at any stage before the cessation of water vapor development from the concrete mass and in cases in which hardening takes place at room temperature before the water content in the concrete mass drops below 10% by weight. \

The phase before the evolution of water vapor ceases the concrete mass can be the period during which the surface of the concrete mass has such a strength that the diameter of a concave indentation that appears on the surface of the concrete mass when an iron ball of

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45o g is dropped onto the concrete from a height of Io cm (hereinafter referred to as the ball drop value), is 40 mm or less, or the phase can be the period from the beginning of the gradual lowering of the highest temperature during heat setting to the removal of the VB- Plate out of the frame. The phase before the water content in the concrete mass drops to less than 10% by weight can be the period from the point in time when the surface of the concrete mass shows a ball drop value of 40 mm or less to the point in time when the water content increases 1p% by weight or more, determined with a concrete water measuring device (manufacturer Kett Science Institute). _;

In the production of VB panels according to the invention, can hardening takes place under natural conditions or, to increase production output, with heating. the Concrete slabs with the applied flowable mass, which is able to form a surface layer, is thus the Hardening at room temperature or subjected to heating to the concrete slab and the layer of the flowable To harden mass at the same time. |

As concrete masses for the slabs, all conventional concrete masses come into question, usually from a hydraulic one Cement (e.g. Portland cement), an aggregate (e.g. Sand and gravel) and water. i

As flowable masses, masses can be used which contain a hydraulic cement as the base material. In general, a filler or aggregate for cement and a liquid sufficient to achieve it are used suitable amount of water mixed with the base material. If necessary, suitable additives, e.g. colorants, aqueous emulsions and other additives can be incorporated. Any conventional hydraulic cements can be used v / earth, however portland cement is advantageous. To form a colored surface layer, it is preferred

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white portland cement is wisely used. As an aggregate powdered silica sand is usually used for cement, but other types of silica or lime can also be used containing substances, e.g. dolomite plaster, volcanic ash, diatomaceous earth, slag, amorphous silicon dioxide, talc, Mica, clay and asbestos can be used. These fillers and additives can be used alone or in combination will. The addition amount is usually about 10 to 200 parts by weight, preferably about 20 to 100 parts by weight per 100 parts by weight of cement. The flow behavior can be improved by adding fillers and additives the flowable mass or a prevention of cracking of the surface layer formed is achieved will. If the amount of filler and aggregate is above the upper limit mentioned, the workability is the flowable mass is insufficient and the surface quality and adhesive strength of the applied layer are bad. If the amount is below the above-mentioned lower limit, cracking of the surface layer occurs and Deterioration in their adhesive strength. As dyes that are occasionally incorporated into the flowable mass are advantageous coloring substances with high alkali resistance, weather resistance and aging resistance used. For example, white pigments, e.g. titanium dioxide, white lead or lithopone or red pigments are suitable Pigments, e.g. red ocher or chrome red, but other pigments with a wide variety of colors can also be used will. The amount of the coloring agent will depend on the desired color of the surface layer selected and is generally about 10 parts by weight or less per 100 parts by weight of cement. If larger quantities are used, the mechanical strength of the Surface layer are affected. As aqueous emulsions, optionally added to the flowable mass at least one customary emulsion which is miscible with the flowable mass can be used. Suitable are for example acrylic resin emulsions, polyvinyl

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acetate emulsions, epoxy resin emulsions, polyvinyl propionate emulsions, Styrene-butadiene copolymer emulsions and vinyl acetate-VeoVa copolymer emulsions. The emulsion can generally used in an amount of about 10 to 60 parts by weight per 100 parts by weight of cement. By admixture This emulsion prevents the dispersion of water and its evaporation when the VB board hardens delayed. A sufficient amount of water can thus be retained for the cement to harden, as a result of which improves the strength of the surface layer, prevents cracking of the surface layer as well as its hydrophilic property is improved and blooming is prevented. This addition of the emulsion is not essential Required if the flowable compound is applied when the escaping water is present in the VB board is. If, on the other hand, the application is carried out when there is no bleeding water, the additive is very effective because the water present in the applied layer is absorbed by the coated substrate can thereby be prevented.

As additives that may be included in the flowable. Mass are incorporated, common substances are suitable, which give the cement an advantageous property and thereby improve its quality. Examples of such " Additives are water-reducing additives, quick setting agents, retardants, agents for rapid solidification, waterproofing agents, water repellants and anti-blooming agents. |

Suitable as flowable mixtures that are used for the purposes of the invention are also masses that are at least an alkali silicate and / or colloidal silica sol as the base material and a filler or aggregate optionally contained together with a coloring agent. Any water-soluble alkali salts of

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acids can be used as alkali silicates. From the
economic point of view is preferably used
Sodium silicate in the form of water glass with an SiO ₂ / Na ₂ O molar ratio of 1.5 to 4.0, potassium silicate in the form of
Potassium water glass with a Si0 ₂ / K ₂ 0 'molar ratio of
1.5 to 4, ο and lithium silicate with a Si0 ₂ / Li ₂ 0 molar ratio of 3.5 to 25.

Suitable colloidal silica sols are silica sols in
Colloid form made up of silica particles of one size
from 1 to 1oo u and with an alkaline or
acidic aqueous solution are stabilized.

Suitable fillers or additives are, for example, clay, talc, mica, barium sulfate, silicon dioxide powder and silica sand. The amount of filler is
usually about 10 to 2000 parts by weight, preferably about 100 to 100 parts by weight per 100 parts by weight of base material. When the amount is larger, the surface layer becomes
very brittle and fragile. If the amount is smaller, the water resistance of the surface layer is insufficient.

Any customary pigments such as titanium dioxide, cobalt blue, chromium oxide or iron oxide are suitable as coloring agents, which are optionally added to the flowable mass. In addition to the pigment, mineral fibers such as asbestos powder and glass fibers can be added to the flowable mass
will. Since the pigments and mineral fibers are important factors for adjusting the appearance of the surface layer, e.g.
Quality and the desired appearance of the surface layer. In order to improve the water resistance of the surface layer, any customary hardness stones can be added to the flowable mass.

The flowable mass according to the invention is on the Surface of the concrete filled into the frame with the help of a conventional spray gun (e.g. a mortar gun) or with the aid of a coating tool (e.g. trowel, brush or roller) within the above-mentioned specified Time applied. The surface of the layer can be smooth and flat, or any other desired Be structured in a way, e.g. in the form of bricks or tiles or depressions. In dependence of With this surface quality, the flowable mass can be applied in a thickness of 0.05 to 5 mm

The concrete slab with the flowable mass applied in this way is then left to harden and finally removed from the frame. The finished VB board provided with the surface layer is not inferior to conventional VB boards in terms of strength and other properties. In terms of adhesive strength and adverse changes due to environmental influences, their surface layer is approximately equivalent to the usual surface layers that are formed on VB panels after hardening. \

The method for producing the VB panels according to the invention can be carried out, for example, as follows be: A concrete mass is poured into a frame. After its surface has been flattened and smoothed, hardening takes place at room temperature or with heating. In the latter case (hardening under exheating) the concrete mass is usually a few hours (e.g. more than 5 hours) at a certain elevated temperature, the but below 40 ° C, held before the surface treatment is finished. The concrete mass is then covered with a Polyvinyl chloride film covered and subjected to the main curing by increasing the temperature at a rate of 20 ° C / hour is increased to about 80 ° C and this temperature is maintained for about 2 to 4 hours, whereupon the

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Teiuperatur is gradually lowered to room temperature. The VB plate produced in this way is then removed from the frame.

The flowable mass is applied according to the invention before the start of the main hardening or during the cooling after the main hardening. The reason why the job with a ball drop value of 40 mm or lower, is that the order is with a higher Ball drop value causes the appearance of leaking water on the surface of the layer, making it brittle and becomes brittle. The order can be made with any ball drop value of 40 mm or less, however, is preferably carried out at a ball drop value of

ι 4o to 12 mm. ;

If the hardening takes place at room temperature (natural hardening), the application of the flowable mass is carried out after the surface treatment and during the time between the point in time at which the surface of the concrete mass has a ball drop value of 40 mm or less and the point in time when the water content '1o wt .-% or more as determined with a concrete: water meter. \

According to the invention, the surface coating of the VB board is carried out on a single production line, in which the VB board is made. In comparison to conventional methods in which the Surface layer is applied after hardening or after completion of the structure, considerable advantages e.g. a reduction in working hours and the elimination of the need for storage on scaffolding. Furthermore, according to the invention, products of constant quality can be manufactured in the factory so that no disturbances occur even in the cold season, while during the usual

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bringing the surface layer in the cold season of the year often the most diverse disturbances such as whitening,: poor adhesive strength and discoloration occur, resulting in the production of flawless surface layers becomes very difficult.

Practical and currently preferred embodiments of the invention are described in the following examples in which parts are parts by weight. the Heat curing is pre-cured using steam. took. The hardening temperature is the temperature in Hardening bath. The adhesive strength is determined by the method described in JIS (Japanese Industrial Standard) A 69o9 is. j

Example T

A concrete mass of 300 parts Portland cement, 800 parts sand, ΙΙ00 parts gravel and 150 parts water with a slump value of 6 cm is placed in a 15 cm deep frame. After standing for 1 hour, the surface of the concrete is smoothed with a wooden trowel. After a ball drop of 40 mm has been determined, a thin-bodied mass consisting of 100 parts of white Portland cement, 35 parts of powdered silica sand, 5 parts of red ocher and 50 parts of water is applied with a mortar gun to a thickness of 1 to 5 mm Surface of the concrete sprayed. The plate is allowed to stand for 2 hours after which the product covered with the sprayed surface layer with a polyvinyl chloride sheet and the temperature increased at a rate of 2O ° C / hour at 80 ⁰ C and is kept 2 hours at 80 ⁰ C. The steam supply is interrupted and the concrete slab is kept at room temperature for 10 hours. The polyvinyl chloride film is removed and the cooled plate is removed from the frame. The surface layer of the VB board produced in this way shows an adhesive strength of To kg / cm and a good surface appearance.

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Example 2

In the manner described in Example 1, but using a thin-bodied mass of 100 parts of white Portland cement, 50 parts of silica sand, 3o parts of dolomite plaster, 2 parts of a waterproofing agent (aluminum stearate), 25 parts of an acrylic resin emulsion (Vinacryl 4OO 1, manufacturer Dainippon Ink Co., Ltd.) and 250 parts of water, one with a 1 to 5 ram. VB plate provided with a thick surface layer. The surface layer has an adhesive strength of 15 kg / cm and shows good appearance.

Example 3

In the manner described in Example 1, but under Use of a thin-bodied mass of 100 parts white Portland cement, 50 parts silica sand, 3o parts dolomite plaster, 2 parts of a waterproofing agent (aluminum stearate), 3o parts of an epoxy resin emulsion ("Prisol L 6ol", manufacturer Dainippon Shikizai Industry Co., Ltd.), 3o parts of a hardening agent (polyamide "PH 52 E" manufacturer Dainippon Shikizai Industry Co., Ltd.) and 2oo A VB board with a surface layer 1 to 5 mm thick is produced from parts of water. The surface layer has an adhesive strength of 12 kg / cm and good appearance.

Example 4

In the manner described in Example 2, but using a polyvinyl propionate emulsion ("Polysol UPIM "Manufacturer Showa Kobunshi Co., Ltd.) instead of the Acrylic resin emulsion in the thin-bodied mass, a VB board is made, which has a surface layer of good quality.

Example 5

In the manner described in Example 2, but under

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Use of an emulsion of a styrene-butadiene copolymer ("Lackster o223A", manufacturer Dainippon Ink Co., Ltd.) Instead of the acrylic resin emulsion in the low-viscosity mass, a VB board with a surface layer of good Quality made.

Example 6 j

The acrylic resin emulsion instead of in the manner described in Example 2, but using an emulsion of a vinyl acetate-VeoVa copolymer ( "Boncoat 662o" _f manufactured by Dainippon Ink Co., Ltd.) in the low viscosity composition is a VB-plate with a surface layer of good quality made.

j Example 7 j

In the manner described in Example 2, but using an emulsion of a vinyl acetate-ethylene copolymer ( ¹¹ EP 9o ", manufacturer Dainippon Ink Co., Ltd.) instead of the acrylic resin emulsion in the thin fluid, a VB plate with a surface layer of good quality made.

j, i

Example 8 |

In the manner described in Examples 1 to 6, however with the application of the thin-bodied mass on the surface of the concrete after reaching the ball drop values 35, 3o, 25, 2o, 15, 1o, 5 or 0 mm become VB plates made with a good quality surface layer. ;

Example 9 _:

A thin-bodied concrete is poured onto the surface of the concrete, which is filled into a frame in the manner described in Example 1 A mass of 100 parts of water glass (sodium silicate), 30 parts of titanium dioxide, 50 parts of clay, 100 parts of powdered material Silica sand, 5 parts asbestos powder and 100 parts water using a compressed air spray

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241 835A

gun applied with a ball drop value of 4o, 3o, 25, 2o, 15, 1o or 5 mm in a thickness of 0.1 to 0.3. The product with the sprayed-on coating is left to stand for one hour at 40 ° C. and then covered with a polyvinyl chloride film covered. The temperature is

_o hour
Speed increased from 2o C / to 8o ^u C and held at 8o ° C for 2 hours. The supply of steam is interrupted and the plate is kept at room temperature for 10 hours. The polyvinyl chloride sheet is removed and the cooled plate removed from the mold. The surface layer of the VB board produced in this way shows an adhesive

strength of 8 kg / cm and good appearance.

Example 1o

In the manner described in Example 9, but using a thin-bodied mass of 70 parts of potassium silicate (SiO2 / K ₂ O = 3.5), 3o parts of colloidal silicon dioxide (Nissan Kagaku Co., Ltd., solids content 3o%), 2o parts Mica, 25 parts of powdered silica sand, 5 parts of asbestos powder and 40 parts of water, a VB board with a surface layer of good quality is made.

Example 1 1 'j

A concrete mass of 300 parts Portland cement, 800 parts sand, 1100 parts gravel and 150 parts water with one The sagging value of 6 cm is placed in a 15 cm high frame filled. The concrete is left to stand for 4 hours and then covered with a polyvinyl chloride film, whereupon the Temperature increased to 80 ° C at a rate of 20 ° C / hour and held at 80 ° C for 2 hours. the The supply of steam is interrupted and the polyvinyl chloride film is removed, leaving a VB plate that develops water vapor is obtained. A thin-bodied mass of the type described in Examples 1 to 10 is applied. That coated product is covered with a polyvinyl chloride film and kept at room temperature for 10 hours.

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The cooled product is taken out of the frame, leaving a VB plate with a surface layer of good Adhesion strength is obtained.

Example 1 2

A concrete mass of 300 parts Portland cement, 600 parts sand and 150 parts water with a flow value of 12o is poured into a 15 cm high frame and left to harden for one day at 20 ° C with a relative humidity of fJo % , with a VB plate is obtained with a water content of more than 1o%. The thin-bodied masses used according to Examples 1 to 10 are applied to the surface of the VB plate in a thickness of 0.5 to 3 mm, the hardening being continued. VB panels with a surface layer with good adhesive strength and appearance are obtained.

For the thin-bodied mass used according to Example 2, the relationships between the falling ball value and adhesive strength are given 1.3 and 7 Tace after the application of the thin-bodied mass is shown graphically in FIGS. 1 to 3. Here the solid line applies to the case of hardening at 20 ° C and a relative humidity of 8o% and the Dashed line for the case of hardening at 20 ° C in water. These results clearly show that the Adhesion strength is excellent at least within the tested ball drop values.

Claims (5)

Claims 1Λ Process for the production of precast concrete slabs provided with a surface - ^ layer, characterized in that a concrete mass is poured into a frame and the concrete mass obtained is hardened and a flowable mass, which is a hydraulic cement or an alkali silicate or a colloidal silica sol as the base material contains, applies to the surface of the concrete mass, this application in cases in which the hardening takes place with heating, in any stage before the cessation of the development of water vapor from the concrete mass and in cases in which the hardening takes place at room temperature, before sinking the water content of the concrete mass below 10 percent - is made.%. 2. The method according to claim 1, characterized in that a flowable mass is used, the 100 parts by weight a hydraulic cement and about 10 to 200 parts by weight of a filler in water. 3. Method according to claim 1 and 2, characterized in that da3 a flowable mass is used, the -100 parts by weight of a hydraulic cement, about 10 to 200 parts by weight of a filler or aggregate and about 10 to 60 parts by weight of at least one: the following aqueous emulsions contains: aqueous emulsions of acrylic resins, aqueous emulsions of polyvinyl acetate, aqueous emulsions of epoxy resins, aqueous emulsions of polyvinyl propionate, aqueous emulsions of styrene-butadiene copolymers and aqueous emulsions of vinyl acetate-VeoVa copolymers. 4. The method according to claim 1 to 3, characterized in that fiai ran flowable masses used as the basic / sr material at least one of the following alkali silicates contain: sodium silicate with a SiOo / NaoO molar ratio nis from 1.5: 1 to 4.0: 1, potassium silicate with a SiOg / KgO molar ratio from 1.5: 1 to 4.0: 1 and Lithium silicate with a SiOp / LiOg molar ratio of 3.5: 1 to 25: 1. 5. The method according to claim 1 to J, characterized in that that one uses flowable masses which contain colloidal silica sol as the base material, in which Silica particles 1 to 100 microns in size with an alkaline or acidic aqueous solution are stabilized. 409844/0 920