DD235685A5 - METHOD FOR IMPROVING THE STRENGTH AND IMPROVEMENT OF BUILDING GROUPS AND ENGINEERING DESIGNS - Google Patents

Abstract

The invention relates to a method for improving the strength and impermeability of floors and technical structures, in particular Schaechten and pipelines. The aim is to reduce the technical-economic effort, to avoid health and environmental damage and to increase the life of the gel. The object is to provide a method by forming a hydrogel of silica and a crosslinked, swellable, organic polymer in or on the treated soil or structure, which ensures a simple and good processability of the mixture without adverse effects on the properties of the gel. According to the invention, an aqueous solution of a water-soluble, gel-forming vinyl monomer with a silica gel precursor in the presence of a redox polymerization catalyst system, a crosslinking agent for the resulting polymer, an organic polycarboxylic acid, optionally an additive which modifies the structure of the gel formed, and optionally contacted with a stuffing.

Description

For this 1 page drawings

Field of application of the invention

The invention relates to a method for improving the strength and impermeability of soils and technical structures, in particular manholes and pipelines.

Characteristic of the known technical solutions

It is well known that most engineering structures such as underground shafts, pipelines and storage tanks do not have the required impermeability properties, in part due to the inadequate quality of the building materials and partly due to damage to the impermeability of the pipe joints or damage to the structures due to aging, wear and tear etc. It is also known that the room temperature of technical structures, especially underground shafts and pipelines, causes enormously high investment and labor, and that in most cases the result is unsatisfactory.

HU-PS 153957 describes a simple and rapid method for improving the strength and impermeability of floors and technical structures. According to this method, water glass or a water glass-containing medium is applied in or on the object to be treated. Subsequently, the water glass is exposed to the action of hydrogen fluoride, silicon tetrafluoride and / or fluorosilicic acid. When water glass comes into contact with gaseous fluoride, it solidifies quickly and completely seals holes, cracks, and hollows. When using this method to waterproof subterranean structures (such as manholes or storage tanks), there is an additional benefit in that water glass entering the soil through the cracks also solidifies, thereby improving the embedding of the structure and strengthening the structure representing surrounding soil. Fluoride gases have the added benefit of improving the corrosion resistance of concrete and reinforced concrete elements.

Regardless of these numerous advantages, this method has been practically used only to a very limited extent. A broad application of this process is considerably limited by the fact that hydrogen fluoride and silicon tetrafluoride are highly toxic and therefore their use for environmental reasons is prohibited in most countries. A further disadvantage is that the resulting silica gel is not elastic and thus can not follow the movements of the treated article or floor. Since the swelling ability of the silica gel is insufficient, it can not close new cracks which form in the gel by agitation.

In the HU-PS 177343,181056,181 775 and 181 573 the use of various polymerizable organic monomers, primarily acrylic acid and acrylamides monomeric as starting compounds for gel-forming reactions is described. The gels formed from such compounds are sufficiently elastic and have a good swelling capacity in water. However, they are relatively soft and can not withstand the damaging effects of higher loads. As an additional disadvantage, most of the monomers used as gelling agents are very expensive and the gel-forming technology requires special training and equipment.

The above-mentioned disadvantages are avoided by the method proposed in Hungarian patent applications 3124/82 and 967/83, in that water glass is used in conjunction with various gel-forming, water-soluble organic polymers and crosslinking agents for the polymers. In these cases, a silica gel precipitates in parallel with the crosslinking of the polymer, and gels are formed consisting of mineral and organic blocks which combine the favorable properties of the complete organic and complete mineral gels. However, it seems very difficult under large-scale conditions, this process

perform. Due to the large molecular weights, the gel-forming polymers increase the viscosity of the starting waterglass solution to such an extent even in small amounts that the resulting mixture is very difficult to handle. Its processing and removal of excess quantities causes numerous technical problems. Often, the required amount of the polymer can not be introduced into the waterglass solution, since a very thick, honey-like mixture has formed which can not be applied to the object to be treated with the common injection devices. Gel-forming mixtures with corresponding low viscosities generally contain a very small amount of polymer, whereby the elasticity and the swellability of the gel obtained is again unsatisfactory.

Object of the invention

The aim of the invention is to reduce the technical and economic effort, to avoid health and environmental damage and to increase the life of the gel.

Explanation of the essence of the invention

The object of the invention is to provide a method for improving the strength and impermeability of soils and technical structures by forming a hydrogel of silica and a crosslinked, swellable, organic polymers in or on the floor or treated structures, without adverse effects the properties of the gel ensures a simple and good processability of the mixture.

According to the invention the object is achieved in that an aqueous solution of a silica gel precursor is brought into contact with a water-soluble, gel-forming vinyl monomer, in the presence

A redox polymerization catalyst system,

A crosslinking agent for the obtained polymer,

An organic polycarboxylic acid,

Optionally an additive which modifies the properties of the gel matrix formed, and

- optionally a filler.

It has thus been found that the stated difficulties and disadvantages of the known prior art can be avoided if, instead of the polymer formed as a precursor, the monomers which lead to the gel-forming polymer are added to the waterglass, and the polymerization and crosslinking of the Polymer is carried out simultaneously with the formation of the silica gel.

Accordingly, the invention relates to a method of improving the strength and impermeability of soils and engineering structures by forming a hydrogel consisting of silica and a crosslinked, swellable organic polymer in or on the treated soil or structure.

In this context, it is noted that the terms "soil" and "technical structure" are to be understood in the broadest sense, including various storage tanks, tunnels, natural and artificial cavities, rocks, etc., and these surrounding soils.

When contacting the aqueous solution of a precursor of the silica gel (eg, an aqueous solution of water glass) with a water-soluble, gel-forming vinyl monomer in the presence of the components described above, the following chemical processes occur simultaneously:

The monomers polymerize according to the mode of action of the redox catalyst system,

The resulting linear polymers react with the crosslinking agent to form a crosslinked polymer gel, and

From its precursor, a silica gel is formed by the action of the polycarboxylic acid.

Since these chemical processes occur in parallel and all intermediates formed in the process interact, a gel is formed in which the organic and mineral parts are amalgamated. The visual appearance of the resulting gel differs markedly from that of the gels obtained according to Hungarian Patent Applications 3124/82 and 967/83. These latter gels are opaque, and the organic and mineral blocks can be easily distinguished in their structure, that is, a gel having an inhomogeneous microstructure is obtained. In contrast, the gels prepared according to the invention are transparent, indicating a homogeneous microstructure. On this basis, it is believed that an organo-mineral copolymer is formed, as opposed to a mixture of organic and mineral polymer blocks.

In the method of the present invention, any substance that forms silica gel on contact with an acid can be used as the silica gel precursor. The preferred representatives of the silica gel precursors are the various water glass types (sodium silicate, potassium silicate, etc.). However, water-soluble silicones and polysilicates can be used, such. For example, those that are commonly used for the production of molds.

Among the water-soluble gel-forming vinyl monomers, the following may be mentioned: acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, water-soluble salts and esters of this acid, acrylamide, methacrylamide, etc. These monomers may be used either alone or as a mixture of two or three monomers. As crosslinking agents for the organic polymers may, for. As aldehydes, (such as glyoxal, glutaraldehyde, etc.) or divinyl or trivinyl compounds (such as methylene-bis-acrylamide, ethylene-bis-acrylamide, triacryltriazine, etc.) are used. The crosslinkers should be sufficiently water soluble, their solubility in water should be at least 1%. The redox catalyst systems used according to the invention consist of an oxidizing and a reducing component. Any of the known redox-type free radical initiator systems commonly used in the preparation of vinyl polymers can be used. The oxidizing component may e.g. Hydrogen peroxide, an alkali metal persulfate or a water-soluble, organic peracid, while the reducing component z. B. a water-soluble organic amine, a water-soluble salt of a metal with we-valences, a thiosulfate, a bisulfite, etc

 Polycarboxylic acids which can be used in the process according to the invention (these are organic carboxylic acids having at least two

Carboxy groups) are ζ. As tartaric acid, succinic acid, citric acid, malic acid, ascorbic acid, etc.

The ratio of silica gel precursors to vinyl monomers, calculated for the dry substances, can be varied over a wide range, e.g. from 10: 1 to 1:10, preferably 5: 1 to 1: 1, most preferably 4: 1 to 2: 1. For economic reasons, it is preferable to use the vinyl monomers in small amounts. It has been observed that the elasticity and swelling properties of the gel remain substantially the same as those of the whole organic gel, equal to a high mineral: organic ratio, in order to further that the higher the silica content of the gel, the greater the strength and resistance to stress.

The ratio of silica gel precursors to polycarboxylic acid, calculated for the dry substances, can be within the following ranges: 1: 0.3 to 1: 0.6, preferably 1: 0.2 to 1: 0.08, in particular about 1: 0 ,1.

The amount of crosslinking agent calculated for the amount of vinyl monomer present may be 1: 0.01 to 1: 0.3,

preferably 1: 0.05 to 1: 0.2. ·

The amount of the redox catalyst system calculated for the mass of the vinyl monomer present may be 1: 0.01 to 1: 0.5, preferably 1: 0.05 to 1: 0.3. Within this range, the catalyst system may contain the oxidizing and reducing components, preferably in approximately equimolar amounts.

If desired, the gel-forming mixture may also contain one or more additives which alter the properties of the gel formed. These additives may be the usual known crosslinked vinyl polymer additives such as plasticizers, stabilizers, decomposition inhibitors, etc., of which melamine, urea, monomethylolurea and thiourea are named. The amounts of such additives, if present, can be up to the amount of vinyl monomer.

If desired, the gelling mixture may contain one or more fillers generally used in such compositions as asbestos, sand, fly ash, bentonite, etc. The amount of such fillers is not critical and is essentially limited by technological factors ( eg stirrability and viscosity of the mixture, ease of handling during application, etc.)

When applying the method according to the invention for the treatment of soil or technical structures, it is possible to mix the individual components of the gel-forming mixture with one another in a corresponding sequence, depending on compatibility factors, directly at the treatment site (eg in the repairing defective tube). , However, it is preferred to start with two preformed aqueous solutions and mix them together at the treatment site. The compositions of the two aqueous solutions should be chosen so that both solutions remain stable and storable for an extended period of time and no premature gelation is produced. To select the appropriate composition of the solutions, the following compatibility factors should be considered:

The silica gel precursor must not be present in a conventional solution with the polycarboxylic acid;

- The two components of the redox catalyst system must not be present in a conventional solution; and

The aqueous solution of the vinyl monomer must not contain the oxidizing component of the redox catalyst system in a free state (although it may contain the oxidizing component in masked form, as a complex).

Taking into account the above compatibility factors, the two aqueous solutions to be mixed at the treatment site may have the following compositions:

Solution "A": silicic precursor (e.g., water glass), oxidizing component of the redox catalyst system) Solution "B": water-soluble vinyl monomer, crosslinking agent for the organic polymer, a polycarboxylic acid,

reducing component of the redox catalyst system, water; or solution "B": water-soluble vinyl monomer, a crosslinking agent for the organic polymer, a polycarboxylic acid,

oxidizing component of the redox catalyst system in masked form (eg complex with urea),

Water Solution "A": a silica gel precursor, reducing component of the redox catalyst system, water.

The "optional" additives and fillers may be added to any of the "A" and "B" solutions, as long as the compatibility requirements are met, therefore, for example, an acidic filler (eg, acidic fly ash) may be added to the solution of Silica gel precursor should not be added.

As stated above, the method according to the invention can be used in the construction industry to improve the strength and impermeability of floors and technical structures. For this purpose, the individual components of the gel-forming mixture - preferably present in two preformed aqueous solutions - mixed together at the treatment site, for. B. in or on the floor or in or on the technical structure. When soil is to be solidified by the method of the present invention, it is preferable to fill the two aqueous solutions in the containers of a two-grooved injector provided with a mixing head and to inject the mixture of the two solutions into the soil to be treated. If a tube shaft is to be repaired by means of the method according to the invention, it is preferable to work with the so-called "filling" technique, where the two solutions are introduced successively into the tube to be repaired.

The process according to the invention combines all the main advantages of the known methods described in the cited patents and patent applications. Like these known methods, it provides a fast, safe and economical way to restore soils or engineering structures strong and watertight. Compared with the known methods, the method according to the invention has the following additional advantages:

- it does not require chemicals harmful to health or the environment;

- It leads to a strong gel that is sufficiently elastic and swellable to compensate for the damage incurred after repair, z. B. of ground movements, wear by traffic, etc.

- the gel-forming mixtures are easy to handle, the treatment requires no special equipment and no special safety measures;

The process is far less than those known using full organic gels;

- The life of the gel produced also exceeds that of the gel prepared by the known methods, which

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embodiment

The invention will be explained in more detail below with reference to some examples. In the accompanying drawing show:

Fig. 1: the schematic representation of a pipe section to be solidified into which the solution "A" is introduced Fig. 2: the pipe section according to Fig. 1, in which the solution "B" is introduced.

example 1

Two aqueous solutions were prepared having the following compositions:

Solution "A"

Water 40 ml

Potassium persulfate 1.8g

Thiourea 14g

concentrated aqueous water glass

(Solution) with a dry substance

of 37 mass /% by mass 50 ml

Solution "B"

Water 80 ml

Methacrylic acid 16 ml

Tartaric acid 10g

Methylene-bis-acrylamide 0.5 g

Iron sulfate 0.5 g

The two solutions were mixed with vigorous stirring. Within 7.5 minutes, a homogeneous, transparent gel formed.

Comparative experiment A

Two aqueous solutions were prepared having the following compositions:

Solution "A", water 90 ml of potassium persulfate 1.5 g

Thiourea 14g solution "B"

Water · 80 ml

Acrylic acid 16 ml

Tartaric acid 10 g methylene-bisacrylamide 0.5 g

Iron sulfate 0.5 g

None of the solutions contained water glass. The two solutions were mixed with vigorous stirring. In 12 minutes, a homogeneous, transparent, completely organic gel was obtained.

Comparative experiment B

Two aqueous solutions were prepared having the following compositions:

Solution "A 40 ml water 14g thiourea concentrated aqueous water glass solution 50 ml (Dry substance 37 mass /% by mass) Solution "B" 80ml water 16g acrylic acid 10 g tartaric acid 0.5 g Methylene-bis-äcrylamid

Since no redox catalyst system was present, no vinyl polymer could be formed. The two solutions were mixed together with vigorous stirring. Within a minute, a cloudy mineral gel formed. The gel showed a strong swelling (syneresis).

Example 2

Two aqueous solutions were prepared having the following compositions:

Solution "A 40 ml water 1.8g potassium persulfate 14g thiourea concentrated water glass solution (Dry substance37 mass /% by mass) in 50 ml aqueous form Solution "B" 80 ml water 16 g acrylic acid 10g succinic acid 2g Methylene-bis-acrylamide ig ferrous sulfate

The two solutions were mixed together with vigorous stirring. Within a minute, a homogeneous, transparent gel formed.

Example 3

Two aqueous solutions were prepared having the following compositions:

Solution "A 70 ml water 0.9 g potassium persulfate 7g melamine concentrated aqueous water glass solution 25 ml (Dry substance 37 mass /% by mass) Solution "B" 80 ml water 16ml methacrylic acid 10g tartaric acid 0.5 g Methylene-bjs-acrylamide 0.5 a ferrous sulfate

The two solutions were mixed with vigorous stirring. Within 120 minutes, a homogeneous transparent gel formed.

Example 4

Two aqueous solutions were prepared having the following compositions:

Solution "A" 16ml water 0.8 g potassium persulfate 6g melamine concentrated aqueous water glass solution 20 ml (Dry substance37 mass /% by mass) Solution "B" 50 ml water 4g itaconic 0.5 g ferrous sulfate 0.5 g Methylene-bis-acrylamide 2g citric acid

The two solutions were mixed together with vigorous stirring. Within 15 minutes, a homogeneous, transparent gel forms.

Example 5

Two aqueous solutions were prepared having the following compositions:

Solution "A" 19ml water concentrated aqueous water glass solution 80 ml (Dry substance 37 mass /% by mass) 1ml triethanolamine Solution "Β" 85 ml water 15ml acrylic acid 10 ml citric acid Hydrogen peroxide in complex with 4g urea 0.5 g Methylene-bis-acrylamide

Table I Compressive strength Example no. kg / m ² 21 1 23 2 15 3 19 4 17 CJL Comparative experiment A13 Comparative experiment B 2

The two solutions were mixed with vigorous stirring. Within 18 minutes, a homogeneous, transparent gel formed.

The compressive strength and deformation of the gels prepared according to the above Examples and Comparative Experiments were measured by standardized methods. The results are summarized in Table 1. It is clear from the tables that the gels prepared according to the invention are superior to those produced by known processes.

deformation

48 55 60 64 61 67 5

Example 6

Solutions "A" and "B" with the compositions given in example 1 were used for the repair of a pipe in the following way:

The pipe section to be treated is shown in FIG. The limited by the shafts 2 and 3 pipe section was cleaned accordingly and then blocked with the pipe closures 1. Thereafter, the sealed pipe section was filled with the solution "A" through the shaft 2. The solution "A" was stored in the tank 4. The required pressure to push the solution into the holes, cracks and cavities was achieved by filling the well to the appropriate height. Depending on the breakage of the tube through which solution "A" emerges, a solution height of about 1 to 2 mm was maintained in the well 2. The solution in the well was, if necessary, filled in. After an appropriate period of time, generally after 10 to 20 minutes, the residual liquid was pumped out of the pipe section via the shaft 2 in the tank 4.

Thereafter, as shown in Fig. 2, the solution "B" was introduced from the tank 6 into the pipe section via the shaft 2. The pressure required to push the solution into the holes, fractures and hollows was again obtained by filling the shaft until The solution is topped up if necessary, and after an appropriate period of time, preferably when it stops, the remainder of the liquid was pumped back into tank 6 via shaft 2, and the pipe closures were removed completed.

If the results are to be checked by water tightness tests using water or air, this may be done before removing the tube seals.

However, this quality control can be avoided by allowing the solution "B" to stay in the well 2 for a corresponding period of time, If the solution level in the well 2 does not decrease within 15 minutes (or the subsidence remains within the prescribed tolerable limits), this is an indication ensure that the pipe is waterproof accordingly.

The solutions "A" and "B" leaked by damaged areas, unsuitable joints or breakages of the pipe form a stable gel 5 inside and / or in the vicinity of the treated pipe. This not only is able to completely block the seepage lines of the pipe but also to solidify the soil surrounding the pipe and make it watertight.

Accordingly, the embedment conditions of the pipe also improve to a high degree, which is a crucial factor with regard to the stability and service life of pipelines.

Claims (4)

Invention claim: A method for improving the strength and impermeability of soils and engineering structures by forming a hydrogel of silica and a crosslinked, swellable organic polymer in or on the floor or treated structure, characterized in that an aqueous solution of a silica gel precursor with a water-soluble, gel-forming vinyl monomers in the presence A redox polymerization catalyst system, A crosslinking agent for the obtained polymer, An organic polycarboxylic acid, Optionally an additive which modifies the structure of the gel formed, and Optionally a filler,
is brought into contact. 2. The method according to item 1, characterized in that the components of the gel-forming mixture are brought into contact by mixing two previously prepared aqueous solutions. 3. The method according to item 2, characterized in that one of the two aqueous solutions containing the silica gel precursor, the oxidizing component of the redox catalyst system and optionally an additive and / or a filler, and the other aqueous solution of the water-soluble vinyl polymer, the Crosslinking agent, the polycarboxylic acid, the reducing component of the redox catalyst system and optionally an additive and / or a filler. 4. The method according to item 2, characterized in that one of the aqueous solutions of the silica gel precursor, the reducing component of the redox catalyst system and optionally an additive and / or a filler, and the other aqueous solution, the water-soluble vinyl polymer, the crosslinking agent containing polycarboxylic acid, the oxidizing component of the redox catalyst system in masked form and optionally an additive and / or a filler.