DE1223291B - Process for connecting set and freshly made building materials containing hydraulic binders - Google Patents

Description

Process for connecting tied and freshly made, Building Materials Containing Hydraulic Binders The invention relates to a method for connecting set and freshly made hydraulic binders containing building materials, in particular concrete, by applying an adhesive layer forming aqueous dispersion of copolymeric or polymeric vinyl compounds and their homologous descendants on the set building material and subsequent application of the freshly prepared building material on the still damp adhesive layer.

All previous methods for joining old and fresh concrete through an adhesive layer containing polyvinyl compounds have the major disadvantage that the adhesive layer is not sufficiently water-repellent and as a result of moisture absorption The adhesive strength between the two parts of the building material is very much to be desired from the environment leaves. The hydrophilic component in the adhesive layer is generally polyvinyl alcohol, as an emulsifier for the emulsion of the polyvinyl compounds forming the adhesive layer serves As the polyvinyl alcohol does not diffuse into the concrete due to its molecular size can, it remains in the adhesive layer and makes it hydrophilic in the long term. at Exposure to moisture causes this layer to swell, causing a reduction the adhesion begins. Especially when using the method in road construction or in connection with other components that are exposed to strong weather conditions these phenomena are very detrimental.

Despite these adverse effects of swelling, there have not yet been any effective countermeasure. It is known to use a PVA emulsion for the purpose of hardening add a condensation resin solution of the polyvinyl alcohol. One such addition however, affects the low water sensitivity of the adhesive layer forming, saponifiable polyvinyl compounds. Above all, the risk of saponification z. B. the PVA resins due to the strong alkalinity of the fresh concrete not corrected will.

The addition of high molecular weight fatty acids as a water repellent agent to plastic dispersions when applying wear-resistant synthetic resin layers in road construction is known, but these are not aqueous dispersions, but rather those in solvents or plasticizers in which the high molecular weight Fatty acids with more than 10 carbon atoms are soluble. Since in this process the introduction the fatty acid in the aqueous plastic dispersions was unknown, is the plastic-containing one Wear layer in a sub-layer, which is an aqueous, fatty acid-free dispersion is applied, and a particularly wear-resistant, as a water-repellent additive top layer containing free fatty acids. However, the contains the The plastic dispersion forming a wear-resistant layer is not water, but a Solvent or a plasticizer as a dispersant. On the one hand, the processing of aqueous plastic dispersions easier and cheaper than the use of Solvent-based dispersions is, on the other hand, the wear layer Should be water-repellent, an aqueous, fatty acid-free cover is first applied and then a fatty acid-containing solvent-based layer. The compulsion to muster of two different layers arises from the fact that the manufacture a fatty acid-containing water-based water-repellent system was not known. The use of such solvent-based hydrophobing systems is not only considerably more expensive than corresponding aqueous solutions, but also very flammable. In the case of highly volatile solvents, vapors are also produced, which are particularly important for large areas that are very annoying to workers involved in applying the layer. The fire hazard of the evaporating solvent is especially in road construction unpleasant due to the manifold possibilities of inflammation. On the other hand it is simple dissolution of the free fatty acids in an aqueous PVA dispersion does not possible because their solubility is far too low. In the case of undecanoic acid, it is of the order of 10-3% and decreases very quickly as the alkyl chain grows. It there was therefore a need to develop a water-based waterproofing agent, that the required high concentrations of the active substance contains and is miscible with the commonly used aqueous PVA dispersions.

The object of the invention is, by adding a suitable aqueous water repellent system for the aqueous dispersion of the polyvinyl compounds to create an adhesive layer between components, which despite the inevitable hydrophilic Compounds is water-repellent and in which the action of humidity does not have an adverse effect.

According to the invention, the water absorption capacity of the adhesive layer is thereby increased eliminated that the adhesive layer forming a colloidal, aqueous dispersion Long-chain water repellent system made from ammonium salts and complex metal salts Fatty acids is added. This makes it possible to make the hydrophilic property more certain to make indispensable compounds in the adhesive layer harmless and through these components caused the generally observed swelling capacity of the adhesive layer practically turn off. The measure described lacks the aforementioned Disadvantages of the previously known and used methods. In particular, you can now Plastic dispersions with practically unlimited levels of water repellant components for the production of adhesive bridges are used: The disperse mixture of copolymers Vinyl compounds preferably consist of PVA resins, polyvinyl propionates and / or Polyvinyl esters and the hydrophobing colloid system are advantageous from a mixture of an ammonium salt of long-chain carboxylic acids with fatty acids Metal complex compounds, especially of polyvalent metal ions of aliphatic Carboxylic acids with 15 to 18 atoms. The adhesive effect can still be improved -if the dispersion mixture -dispersible, additively crosslinking reacting- synthetic resins, z. B. epoxy soft resins and crosslinking agents such as amines, amides, polyamines; Polyamides or amine adducts are added. In the latter case, an addition of minor Quantities of substances that accelerate the reaction, such as - phenols, phenol homologues to the dispersions be appropriate. The mixture used to form the adhesive bridge can also Dispersion water-binding additives, e.g. B. hydraulic binders, and water, acid, oil and gasoline-resistant fillers, e.g. B. quartz flour .be added.

A normal top concrete in one is advantageous on the adhesive layer Approximately 0.5 to 1 cm thick. This top concrete can. in familiar Wise setting accelerators such as calcium chloride or aluminate-carbonate mixtures can be added. Furthermore - it is to increase - the flexural tensile strength and compressive strength and to achieve water and gasoline acid and oil resistance - advantageous - if about 10 to 20% of the synthetic resin dispersion is added to the top concrete.

The hydrophobic effect of certain metal soaps in concrete mixes has been known for a long time. - But so far there was no way to use metal soaps, even if they were in the finest powdered form, so homogeneously with synthetic resin dispersions or to mix emulsions that in the films formed therefrom a completely even distribution of these substances occurred. Experiments showed that always the individual particles of these materials are anchored in the film in places, while show imperfections in other parts of the film, even if the individual particles were very small.

It was found that, in contrast, a continuous distribution succeeds in the material if the metal soaps are made by adding ammonium compounds be converted into addition complexes, which have the property of colloidal Forming solutions. Polyvalent heavy metal ions in Connection with long-chain fatty acids and ammonia. These complex formation reactions, the chemical process of which cannot yet be precisely understood occur within from 15 to 20 minutes at temperatures between 80 and 90 ° C, and the resulting Colloid systems can be made completely homogeneous in synthetic resin dispersions without difficulty Stir in or emulsions and give the films formed from them completely uniform hydrophobic properties.

It has also been found that such films when exposed to moisture Absorb 80% less water than. Films made from vinyl polymer dispersion without such Additions.

It was also observed that small additions of ammonium salts long chain fatty acids, e.g. B. ammonium stearate, the re-emulsifiability of the synthetic resin films further reduce and - at the same time the risk of saponification - between the strong alkaline-reacting calcium compounds in fresh concrete and PVA resins reduce significantly. A mixture of equal parts proved to be more soluble fatty acid ammonium salts and metal-amino-hydroxo complex compounds, preferably from polyvalent heavy metals and long-chain carboxylic acids, as an additive to emulsions or dispersions of vinyl polymers.

It was also found; that such mixtures, especially after Addition of hydraulic substances and silicate compounds, a good bonding agent between old and fresh concrete. That as thin sludge on the surface The mixture applied to cleaned old concrete enables an indissoluble permanent connection with the rammed fresh concrete. When the bonding bridge sets, it is likely to occur following chemical reaction to: The alkaline reacting calcium compounds of the hydraulic building material decompose the colloidally dissolved fatty acid metal complexes with the formation of hydrophobic metal soaps, water and ammonia. The latter escapes gaseous, so that no harmful ammonium salts remain in the concrete. aside from that the fatty acid ammonium salts of the mixture react with the soluble calcium compounds the hydraulic building materials with the formation of poorly soluble metal soaps and prevent thus the risk of saponification of the PVA resins.

It was also found that aging resistance, adhesiveness and compressive strength of the adhesive bridge can be increased if a pure vinyl polymer dispersion is not used used, but mixtures of such synthetic resins with additive crosslinking reacting Plastics.

According to the method of the invention, stable dispersion has been achieved made of vinyl polymers and crosslinking synthetic resin mixtures, e.g. B. epoxy resins and polyamine and polyamide compounds, respectively to manufacture. When mixed with hydraulic building materials, the dispersion water of such mixtures is called Bound water of hydration and thus withdrawn from the mixture as free water. Through this the crosslinking reaction between the additive synthetic resins, z. B. epoxy compounds, and the crosslinking agents, e.g. B. polyamides. The macromolecules formed are incorporated evenly into the vinyl polymer film. Whether further reactions between the vinyl polymers and the crosslinked synthetic resins what can be assumed has not yet been precisely established.

Experiments clearly showed that such combinations a much better adhesion, even on smooth and pore-free material surfaces, than the pure vinyl polymer films.

In addition, the resistance of the concrete increases with such mixtures against water, mineral oil, motor fuel, acids, bases and other chemical compounds.

It was also found that small additions of phenols or Phenolic homologues, which are known as reaction accelerators for epoxy resin systems Find use, also in the listed dispersion mixtures of vinyl polymers and crosslinking two-component synthetic resins have a hardening-accelerating effect. If one to such mixtures in connection with hydraulic building materials setting accelerators for the latter, like mixtures of aluminates or alkali carbonates, can be added synthetic concrete can be produced which has significantly shorter setting and hardening times own as normal concrete. Such combinations are economical in road construction special importance where the shortest possible repair times are desired. Also enable catalytic additives based on phenols result in a relatively rapid crosslinking of the two-component resins even at lower temperatures down to the freezing point and at relatively high temperatures Humidity, which is particularly important for repair work in the cold season is technically very advantageous.

The synthetic resin dispersions developed according to the method of the invention can be used not only as bonding bridges between old and fresh concrete, but also as bonding agents between fresh concrete and other building materials such as metals including aluminum, wood, asbestos cement, terrazzo, etc. It has been found that the adhesiveness of such plastic mixtures is so great that insoluble compounds can be produced with other materials even on completely smooth and pore-free surfaces. Strength tests have shown that additions of the synthetic resin dispersions prepared according to the invention to concrete mixes bring about a considerable increase in compressive and flexural strength, which is retained even after prolonged exposure to moisture, as the following table shows: Bending tensile compressive strength Bending tensile compressive strength Composition strength setting time strength water layer after 28 days after 7 days kg kg kg kg Basic mixture: 1 part Portland cement, 3 parts sand 0 to 3 mm. . 48 360 38 320 Mixture as 1, addition of 20% PVA dispersion (50o / oig) ..................................... 58 298 42 243 Mixture like 1 -h 20% additive A *) .............. 65 322 58 320 Mixture like 1 -I- 20% additive B *) .............. 82 536 78 526 Composition of additives: A = 40% internally plasticized PVA dispersion, B = 25% PVA dispersion, 50% plasticizer-free PVA dispersion, 25% epoxy resin-polyamide mixture, 10% colloidal fatty acid iron complex solution **); 50% water. **) The colloidal fatty acid iron complex solution was prepared as follows: 10 parts of iron palmitate were suspended in a 50% strength ammonium hydroxide solution and stirred slowly Bred to a temperature of 80 to 90 ° C for 20 minutes. A completely homogeneous colloid solution that did not flocculate even after a long period of time. (The same results were obtained between iron stearate, aluminum stearate, zinc stearate and ammonium hydroxide.) Example 1st stage Two separate approaches were made for the production of firmly adhering water- and oil-resistant concrete additives based on synthetic resin. Approach I. 100 parts of copolymer dispersion, 66 parts liquid epoxy resin, 100 parts of water, 10 parts colloidal fatty acid metal complex Solution. Approach II 100 parts of copolymer dispersion, 34 parts of polyamides, polyamines or amine adducts, 100 parts of water, 10 parts colloidal fatty acid metal complex Solution. Production was carried out by homogeneously mixing the individual additives in the order listed with a high-speed mixer until a homogeneous dispersion had formed. Both components can be stored indefinitely when stored in separate containers.

2nd stage Before processing as a bonding agent between old and Fresh concrete equal parts of batches 1 and 2 were mixed well and mixed with the required Mixing water, hydraulic aggregates and silicate fillers in one Mixed sludge. After cleaning the old concrete surface by sweeping and The slurry was applied in a thickness of about 1 to 2 mm and sprayed with water then on the still moist adhesive layer an earth-moist top concrete in a familiar Composition tamped 0.5 to 1 cm thick.

For use as an adhesion promoter on non-porous building materials such as Metal, terrazzo, etc., the pure synthetic resin dispersion is expedient without additives used by fillers.

In the production of an oil-, petrol-, acid- and water-resistant concrete, the following composition has proven to be favorable for application as top concrete on the adhesive layer produced according to the method of the invention: 35 parts by weight of Portland cement, 5 parts by weight synthetic resin mixture from approach 1 and 2, 60 parts by weight of sand 0 to 3 mm.

Claims (4)

Claims: 1. Method for connecting tied and freshly made building materials containing hydraulic binders, in particular Concrete, by applying an aqueous dispersion of copolymers forming the adhesive layer Vinyl compounds on the set building material and then applying the freshly prepared building material on the still damp adhesive layer, characterized by that the dispersion forming the adhesive layer has an aqueous colloidal water repellent system from ammonium salts and complex metal salts of long-chain fatty acids added will. 2. The method according to claim 1, characterized in that dispersible, Additively crosslinking synthetic resins and crosslinking agents of the adhesive layer forming dispersion are added. 3. The method according to claim 1 or 2, characterized characterized in that small amounts of the dispersions accelerate the reaction Substances, e.g. B. phenols or phenol homologues can be added. 4. Procedure after a of claims 1 to 3, characterized in that dispersion water-binding additives, z. B. hydraulic binders, and water, acid, oil and gasoline-resistant fillers, z. B. quartz powder can be added. Publications considered: German U.S. Patent No. 966,648; German Auslegeschriften Nos. 1054 900, 1061689; German Interpretation document G 10569 V / 19 e (published on October 31, 1956).