EP0352172B1 - Process for sealing a sheet piling - Google Patents

Abstract

Process for sealing a sheet piling by introducing into the empty space between the locked complementary loops a fluid system which is capable of forming "in situ", at the temperature prevailing in the empty space, a gel or resin occupying the entire volume of the empty space as a result of swelling on contact with the medium to be sealed. The sheet piling is especially useful for separating a liquid medium from a solid medium or two solid mediums.

Description

The subject of the present invention is a method for making sheet pile curtains tight to liquids or pollutants contained in solids.

It is agreed to use in the public works industry metal sheet piles comprising a core with a particular non-planar profile, provided on each of its longitudinal edges with a loop which extends continuously from one end to the other of the sheet pile, each of the two loops being complementary to each other. The longitudinal engagement of each of the two loops of each adjacent sheet pile forms a locked structure called a curtain.

This type of structure is particularly used to separate a liquid medium from a solid medium, for example for the defense of the banks of canals and rivers, as a screen for the protection of flood zones ..., or to separate two solid media , for example to separate a healthy soil from a soil contaminated by metals or various chemicals (metal salts, solvents, hydrocarbons ...).

However, the empty space existing between the two locked complementary loops is more or less closed; Also, the sealing of such a structure is not always sufficient, in particular in the event of accidental pollution of the water table, in particular when the latter is located at a shallow depth.

It is known to introduce into the sheet pile joints installed in the ground resin powders, capable of swelling by absorption in the soil moisture, and a non-aqueous liquid, (see abstract of patent JP-A-58189 417) .

The Applicant has found a particularly simple method for sealing the sheet pile locking systems.

• une substance éthyléniquement insaturée diluée dans l'eau, susceptible de former par polymérisation et/ou réticulation une résine ou un gel solides,
• un amorceur de polymérisation et/ou de réticulation,
• et un agent gonflant en milieu aqueux lorsque le gel ou la résine formé(e) ne gonfle pas ou pas suffisamment de lui-même ou d'elle-même au contact du milieu aqueux présent dans la zone à étancher,

le temps de prise dudit système étant inférieur à 1 heure environ. Les gels ou résines mis en oeuvre ou formés "in situ" peuvent être de consistance plus ou moins élastique ; ainsi des gels ou résines d'aspect relativement dur peuvent être mis en oeuvre s'ils sont susceptibles de gonfler au contact du milieu présent dans la zone à étancher.To this end, the subject of the invention is a method for sealing sheet pile curtains by introducing into the empty space existing between the locked complementary loops of said curtains a fluid system capable of forming at the temperature prevailing inside said space. , a gel occupying the volume of said space, by swelling in contact with an aqueous medium present in the zone to be sealed, characterized in that the fluid system has a viscosity of less than 15 Pa.s and consists of:

• an ethylenically unsaturated substance diluted in water, capable of forming, by polymerization and / or crosslinking, a solid resin or gel,
• a polymerization and / or crosslinking initiator,
• and a swelling agent in an aqueous medium when the gel or the resin formed does not swell or does not swell sufficiently by itself or itself in contact with the aqueous medium present in the zone to be sealed,

the setting time of said system being less than approximately 1 hour. The gels or resins used or formed "in situ" can be of more or less elastic consistency; so gels or relatively hard-looking resins can be used if they are liable to swell on contact with the medium present in the area to be sealed.

• une substance fluide susceptible de "durcir" à la température régnant à l'intérieur des boucles verrouillées du rideau de palplanches,
• un agent de "durcissement" de ladite substance fluide,
• et un agent gonflant au contact du milieu présent dans la zone à étancher si ladite substance ne gonfle pas ou pas suffisamment d'elle-même au contact dudit milieu.

The fluid system used comprises at least the following essential elements:

• a fluid substance capable of "hardening" at the temperature prevailing inside the locked loops of the sheet pile wall,
• an agent for "hardening" said fluid substance,
• and a swelling agent in contact with the medium present in the area to be sealed if said substance does not swell or does not swell enough on its own in contact with said medium.

By setting time is meant the time interval between the moment when the various constituents of the fluid system are mixed and the moment when the product obtained no longer flows. This setting time is easily adjustable depending on the temperature by varying the various system parameters.

The term "fluid system" means a system whose viscosity is less than 15 Pa.s, preferably less than 1 Pa.s.

A viscosity close to that of water is sought when the area to be sealed contains terrain elements of fineness less than or equal to that of sand or when the speed of circulation of the medium in the area to be sealed is low. On the other hand when the circulation of the medium in the zone to be sealed is important, it is preferable to use a more viscous system in order to avoid its too strong dilution by the medium.

According to the invention the term "harden" means to pass from the fluid state to a more or less elastic cohesive solid state.

The fluid substance and the "hardening agent" are preferably not brought into contact with each other until they are introduced into the empty space. However, they can be mixed in advance when the setting time of the grout obtained is high or when the rate of introduction of this grout is very fast.

The process according to the invention is particularly advantageous to make the sheet piling waterproof to liquids, whether the latter are aqueous (fresh water, salt water, brackish water, variously polluted water ...), hydrocarbon (petroleum products, petroleum derivatives ...).

A particularly important application consists in sealing the sheet pile walls vis-à-vis aqueous media.

The fluid system used can be aqueous or non-aqueous.

• une substance éthylèniquement insaturée, diluée dans l'eau, susceptible de former par polymérisation et/ou réticulation une résine ou un gel solide,
• un amorceur de polymérisation et/ou de réticulation,
• éventuellement un agent gonflant en milieu aqueux lorsque le gel ou la résine formé(e) ne gonfle pas ou pas suffisamment de lui-même ou d'elle-même au contact du milieu aqueux présent dans la zone à étancher.

As a first example of an aqueous fluid system, mention may be made of those consisting of:

• an ethylenically unsaturated substance, diluted in water, capable of forming, by polymerization and / or crosslinking, a solid resin or gel,
• a polymerization and / or crosslinking initiator,
• optionally a swelling agent in an aqueous medium when the gel or the resin formed does not swell or does not swell enough of itself or of itself in contact with the aqueous medium present in the zone to be sealed.

• les monomères monoéthylèniquement insaturés solubles ou dispersables dans l'eau, comme par exemple les monomères acryliques hydrosolubles du type acide acrylique, acrylamide, N-alkylacrylamides dont le radical alkyle est en C₁-C₄, le methylolacrylamide, le methylolmethacrylamide, les acrylates d'alkyle en C₁-C₄, les acrylates minéraux..., en mélange avec au moins un monomère réticulant di- ou poly-éthylèniquement insaturé soluble ou dispersable dans l'eau du type méthylène-triacrylamide, méthylène bis-methacrylamide, dihydroxy-1,2 éthylène bis- acrylamide, dihydroxy-1,2 éthylène bis-methacrylamide, n-methylol- dihydtoxy-1,2 éthylène bis-acrylamide, bis(acrylamidomethyl)-1,3 imidazolidone-1,2, bis(methacrylamidomethyl)-1,3 imidazolidone-2.
• les oligomères, homopolymères ou copolymères de faible masse moléculaire dérivés de monomères monoéthylèniquement insaturés solubles ou dispersables dans l'eau tels que ceux cités ci-dessus, en mélange avec au moins un monomère réticulant di- ou poly-éthylèniquement insaturé soluble ou dispersable dans l'eau tels que ceux cités ci-dessus.
• les polymères vinyliques peu sensibles à l'eau en mélange avec des monomères monoéthylèniquement insaturés solubles ou dispersables dans l'eau tels que ceux cités ci-dessus, et éventuellement au moins un monomère réticulant di- ou poly-ethylèniquement insaturé soluble ou dispersable dans l'eau tel que ceux cités ci-dessus. Parmi les polymères vinyliques peu sensibles à l'eau on peut mentionner les copolymères du styrène et de monomères du type acrylate ou méthacrylate de méthyle, éthyle, isopropyle, n-butyle, isobutyle, cyclohexyle...

Among the ethylenically unsaturated substances that may be mentioned:

• monoethylenically unsaturated monomers soluble or dispersible in water, such as, for example, water-soluble acrylic monomers of the acrylic acid, acrylamide, N-alkylacrylamides type, the alkyl radical of which is C₁-C₄, methylolacrylamide, methylolmethacrylamide, alkyl acrylates in C₁-C₄, the mineral acrylates ..., mixed with at least one di- or poly-ethylenically unsaturated crosslinking monomer soluble or dispersible in water of the methylene-triacrylamide, methylene bis-methacrylamide, dihydroxy-1,2 type ethylene bis-acrylamide, 1,2-dihydroxy ethylene bis-methacrylamide, n-methylol-1,2-dihydtoxy-ethylene bis-acrylamide, bis (acrylamidomethyl) -1,3 imidazolidone-1,2, bis (methacrylamidomethyl) -1,3 imidazolidone-2.
• low molecular weight oligomers, homopolymers or copolymers derived from water-soluble or water-dispersible monoethylenically unsaturated monomers such as those mentioned above, mixed with at least one di- or poly-ethylenically unsaturated crosslinking monomer soluble or dispersible in water such as those cited above.
• vinyl polymers which are not very sensitive to water when mixed with water-soluble or dispersible monoethylenically unsaturated monomers such as those mentioned above, and optionally at least one di- or poly-ethylenically unsaturated crosslinking monomer soluble or dispersible in water. such as those cited above. Among the vinyl polymers that are not very sensitive to water, mention may be made of copolymers of styrene and of monomers of the methyl acrylate or methacrylate type, ethyl, isopropyl, n-butyl, isobutyl, cyclohexyl, etc.

In these types of ethylenically unsaturated substances, the level of crosslinking monomer can represent up to 5% of the weight of the monoethylenically unsaturated monomer soluble or dispersible in water.

The polymerization and / or crosslinking initiator entering the fluid system is generally a free radical generating compound soluble in water or miscible with it such as potassium or ammonium persulfate, hydrogen peroxide , acetyl peroxide, propionyl, phenylacetyl, benzoyl, t-butyl, benzyl, cumyl peroxide ...

The amount of initiator generally represents 0.1 to 5% of the weight of the monoethylenically unsaturated monomer (s) soluble (s) or dispersible (s) in water.

It is preferably combined with a reducing accelerator, in a similar amount, such as sodium pyrosulfite, sodium metabisulfite, tertiary amines such as dimethylaminoptopionitrile, dimethylaminoacetonitrile, triethanolamine, dimethylethanolamine, tetramethylethylenediamine.

The rate of accelerator allows to play on the setting time.

• les silicates alcalins additionnés au moment de l'emploi d'un réactif gélifiant ; il s'agit de silicates ou polysilicates de sodium ou de potassium avec un rapport molaire SiO₂/M₂O de l'ordre de 2 à 5, dont la gélification est réalisée par addition séparée d'un gélifiant du type triacétine, bicarbonate de sodium, esters alkyliques d'acides carboxyliques (mono-, di- ou tri-esters méthyliques et/ou éthyliques), glyoxal, aluminate de sodium.
• des épaississants à base de polymères hydrosolubles tels que polyacrylamides, polyacrylamides hydrolysés, acides polyacryliques, sels d'acides polyacryliques, polysaccharides (gomme xanthane...).

Other constituents can also enter aqueous fluid systems based on monoethylenically unsaturated monomers soluble or dispersible in water. These are for example:

• alkali silicates added at the time of use of a gelling reagent; these are sodium or potassium silicates or polysilicates with a SiO₂ / M₂O molar ratio of the order of 2 to 5, the gelling of which is carried out by separate addition of a gelling agent of the triacetin, sodium bicarbonate, ester type alkyl of carboxylic acids (mono-, di- or tri-methyl and / or ethyl esters), glyoxal, sodium aluminate.
• thickeners based on water-soluble polymers such as polyacrylamides, hydrolyzed polyacrylamides, polyacrylic acids, polyacrylic acid salts, polysaccharides (xanthan gum ...).

Aqueous fluid systems of the type of those mentioned above are described in the French patents published under the numbers 1,458,945 and 2,375,288.

• un polymère soluble ou dispersable dans l'eau susceptible de former par réticulation une résine ou un gel élastique,
• un agent de réticulation dudit polymère,
• et éventuellement un agent gonflant à l'eau.

As a second example of an aqueous fluid system which can be used, mention may be made of those consisting of:

• a water-soluble or dispersible polymer capable of forming a resin or an elastic gel by crosslinking,
• a crosslinking agent for said polymer,
• and optionally a water blowing agent.

By way of example of polymers soluble or dispersible in water, mention may be made of natural or synthetic products such as polyacrylamide, partially hydrolyzed polyacrylamides, polyacrylonitrile, carboxymethylcellulose, polyvinylpyrolidone, polyvinyl alcohol, polysaccharides, l polyacrylic acid and its derivatives, polyethylene glycol, polyethylene oxides and / or propylene, alginates, carragenates, gums (agar, arabic ...), pectins, starch, alkyls and hydroxyalkyl celluloses .

• des cations Fe²⁺, Fe³⁺, Al³⁺, Ti⁴⁺, Zn²⁺, Sn⁴⁺, Ca²⁺, Mg²⁺, Cr³⁺... complexés par un anion du type acétate, notrolotriacétate, tartrate, citrate, tripolyphosphate, métaphosphate, gluconate, phosphate...
• ou des aldéhydes tels que formaldéhyde, acétaldéhyde, aldéhyde glutarique... pour les polymères susceptibles de réagir avec les aldéhydes.

The crosslinking agents are generally:

• cations Fe²⁺, Fe³⁺, Al³⁺, Ti⁴⁺, Zn²⁺, Sn⁴⁺, Ca²⁺, Mg²⁺, Cr³⁺ ... complexed by an acetate, notrolotriacetate, tartrate, citrate, tripolyphosphate, metaphosphate, gluconate anion , phosphate ...
• or aldehydes such as formaldehyde, acetaldehyde, glutaric aldehyde ... for the polymers capable of reacting with the aldehydes.

• les résines aminoplastes telles que les résines urée-formaldéhyde, mélanine-urée-formaldéhyde, urée-formaldéhyde-acétone, éventuellement modifiées par de l'acrylamide, du furfuramide, du furfurol, de l'alcool polyvinylique...;
• un agent de durcissement de type acide tel que acide oxalique, acide phosphorique...;
• et éventuellement, un agent gonflant à l'eau.

Another type of example of a fluid aqueous system is constituted by:

• aminoplast resins such as urea-formaldehyde, melanin-urea-formaldehyde, urea-formaldehyde-acetone resins, optionally modified with acrylamide, furfuramide, furfurol, polyvinyl alcohol, etc .;
• an acid-type hardening agent such as oxalic acid, phosphoric acid, etc.;
• and optionally, a water blowing agent.

The amount of curing agent used is chosen according to the desired setting time of said system.

Water blowing agents can be used if the gel or the elastic resin formed by crosslinking or hardening of the ethylenically unsaturated substance or aminoplast does not swell or insufficiently in contact with water. These agents are of the polyacrylamide, carboxymethylcellulose, polysaccharide, natural gum (guar ...) type.

• des charges renforçantes ou diluantes (talc, oxyde de titane, kaolin, cendres volantes, craie, fumée de silice, bentonite, ciment, plâtre...).
• des agents anti-corrosion
• des anti-gel
• des agents de gravité (sulfate de baryum, bromure ou chlorure de potassium...).
• des agents dispersants...

Auxiliary products can also be present in the fluid system whatever the nature of the latter, such as for example:

• reinforcing or diluting fillers (talc, titanium oxide, kaolin, fly ash, chalk, silica smoke, bentonite, cement, plaster ...).
• anti-corrosion agents
• anti-freeze
• gravity agents (barium sulphate, bromide or potassium chloride ...).
• dispersing agents ...

The swelling capacity of the fluid system after gelation or hardening is adjustable in various ways: concentration of active material, rate of crosslinker, rate of swelling agent, rate of fillers, etc.

• le ROCAGIL BT ou BT-2 à base de solution aqueuse de methylolacrylamide présentant un temps de prise pouvant aller de quelques secondes à plus d'une heure à la température ambiante en fonction du taux de catalyseur et de retardateur de prise mis en oeuvre
• le SIPROGEL 110-25 à base de solutions aqueuses de monomère acrylique et de silicate de sodium, présentant un temps de prise de l'ordre de 2 à 47 minutes à 20°C selon la concentration d'accelérateur mise en oeuvre.
• le ROCAGIL AL6, coulis aqueux à base de monomère acrylique, présentant un temps de prise de l'ordre de 30 à 40 minutes à 20°C, selon la quantité d'initiateur mise en oeuvre.
• le ROCAGIL F22U à base de résine aqueuse aminoplaste à durcissement acide, présentant un temps de prise de l'ordre de 22 à 40 minutes à 30°C suivant la concentration en catalyseur.

By way of example, mention may be made of commercial products which are particularly suitable as an aqueous fluid system for carrying out the invention:

• ROCAGIL BT or BT-2 based on aqueous methylolacrylamide solution having a setting time which can range from a few seconds to more than an hour at room temperature depending on the level of catalyst and setting retarder used
• SIPROGEL 110-25 based on aqueous solutions of acrylic monomer and sodium silicate, having a setting time of the order of 2 to 47 minutes at 20 ° C. depending on the concentration of accelerator used.
• ROCAGIL AL6, aqueous grout based on acrylic monomer, having a setting time of around 30 to 40 minutes at 20 ° C, depending on the amount of initiator used.
• ROCAGIL F22U based on aqueous aminoplast resin with acid hardening, exhibiting a setting time of the order of 22 to 40 minutes at 30 ° C. depending on the concentration of catalyst.

All these products are marketed by Rhône-Poulenc.

A particularly suitable mode of introduction of the fluid system into the empty space existing between the locked complementary loops is the injection under pressure, after mixing, of the various constituents of the fluid system by means of an injection probe.

In particularly simple cases (absence of water, earth or alluvium in the loops, with a reduced number of sheet piles) one can consider filling the area to be sealed by simple gravity.

The process which is the subject of the invention can be used to seal any type of sheet pile curtain, whether these are formed from a core with a particular profile in Ω, in U, in S in z or other.

Such sheet piles are described in French patent application No. 2,613,960 to PROFILES AND TUBES OF THE EAST.

Fluid systems capable of forming an inflatable resin or gel are suitable for all locking systems.

The following examples, given by way of illustration, make it possible to highlight other advantages of the invention without however limiting its scope, within the scope of the appended claims.

EXAMPLE 1

• 100 g d'une solution aqueuse contenant 10 g de methylacrylamide, 0,5 g de persulfate de potassium et 0,4 g de triethanolamine
• à 80 g d'une solution aqueuse de silicate de sodium à 30,5 % en poids d'extrait sec, de rapport molaire SiO₂/Na₂O égal à 3,9, ladite solution étant diluée dans 100 g d'eau. On incorpore ensuite 13 g de triacétine

The following are stirred:

• 100 g of an aqueous solution containing 10 g of methylacrylamide, 0.5 g of potassium persulfate and 0.4 g of triethanolamine
• to 80 g of an aqueous sodium silicate solution at 30.5% by weight of dry extract, of SiO₂ / Na₂O molar ratio equal to 3.9, said solution being diluted in 100 g of water. 13 g of triacetin are then incorporated.

The grout obtained having a setting time of the order of 15 minutes at 20 ° C can be introduced by injection using a single-circuit system into the volume to be sealed; he is particularly suitable for injection into a sealed volume containing an aqueous medium containing fine sand.

EXAMPLE 2

• d'une part, 100 g d'une solution aqueuse contenant 10 g de methylolacrylamide, 0, 4 g de triethanolamine et 13 g de triacetine
• et d'autre part, 80 g de solution aqueuse de silicate de sodium à 30,5 % en poids d'extrait sec, de rapport molaire SiO₂/Na₂O égal à 3, 9, solution à laquel le on ajoute 100 g d'eau et 0,4 g de persulfate de potassium.

We prepare :

• on the one hand, 100 g of an aqueous solution containing 10 g of methylolacrylamide, 0.4 g of triethanolamine and 13 g of triacetin
• and on the other hand, 80 g of aqueous sodium silicate solution at 30.5% by weight of dry extract, of SiO₂ / Na₂O molar ratio equal to 3, 9, solution to which 100 g of water are added. and 0.4 g of potassium persulfate.

The two solutions are introduced by injection using a double circuit system into the volume to be sealed; the setting time of the final grout is around 15 minutes at 20 ° C. This injection mode makes it possible to operate for a longer time, the mixing only taking place at the outlet of the injection pump.

EXAMPLE 3

On the one hand, 0.15 kg of triethanolamine in solution in 0.15 kg of glycol in 50 liters of a commercial solution of ROCAGIL BT (solution based on methylolacrylamide) sold by Rhône-Poulenc is added; we obtain a set A.

On the other hand, 0.3 kg of sodium persulfate is added to 50 liters of water; we obtain a set B.

The mixture of the two sets forms a grout whose setting time is 5 minutes at 20 ° C and which swells with water.

This very fluid grout can be set up by injection using a dual circuit system; it is particularly suitable for injection into a volume to be sealed containing an aqueous medium containing fine sand.

EXAMPLE 4

0.3 kg of sodium persulfate is dissolved in 50 liters of water containing 0.2% of its weight of RHODOPOL 23 (xanthan gum sold by Rhône-Poulenc); we obtain a set C.

We mix a set equivalent to set A of the example 3 to set C; this mixture forms a grout whose setting time is 5 minutes at 20 ° C. The installation of this grout can be done by injection using a double circuit material. It is particularly suitable for injecting the volume to be sealed when it contains rapidly changing water.

EXAMPLE 5

Was mixed with 92 liters of commercial solution of ROCAGIL AL6 marketed by Rhône-Poulenc (based on a water-soluble acrylic monomer and a dispersion of a styrene-acrylic copolymer), 0.5 kg of sodium persulfate dissolved in 8 liters of water.

The grout obtained has a setting time of around 37 minutes at 20 ° C and swells with water; it is particularly suitable for injection into a volume containing water with low circulation and containing small quantities of sand.

EXAMPLE 6

92 kg of ROCAGIL AL6 commercial solution are mixed with 1 kg of sodium persulfate dissolved in 8 liters of water.

The grout obtained has a setting time of the order of 12 minutes at 20 ° C and swells with water; its application is similar to that of the grout of Example 5.

EXAMPLE 7

Firstly, to 92 liters of commercial solution of ROCAGIL AL6, 0.5 kg of RHODOPOL 50 MD (xanthan gum marketed by Rhône-Poulenc) and 500 g of triethanolamine are added to 500 g of ethylene glycol; we obtain a set D.

On the other hand, 1 kg of sodium persulfate is dissolved in 8 liters of water; we obtain a set E.

The mixture of sets D and E constitutes a viscous grout which swells with water, a grout whose setting time at 20 ° C. is 7 minutes.

Due to its viscosity, this grout does not dilute in circulation water.

EXAMPLE 8

A mixture of 50 liters of ROCAGIL AL6 and 1.5 kg of sodium persulfate dissolved in 5 liters of water is homogenized. 100 kg of CPA 55 standardized cement are introduced into this mixture with stirring.

A grout is obtained whose setting time is between 11 and 15 minutes at 20 ° C and which, after a few days of storage forms a hard material capable of swelling in water; this material has a monoaxial compressive strength of 15 mega Pa.

Such a grout is particularly well suited for injection into a volume containing water or in a vacuum.

EXAMPLE 9

On the one hand, 500 g of triethanolamine in 500 g of ethyleneglycol are added to 92 liters of commercial solution of ROCAGIL AL6; we obtain a set F.

On the other hand, 1 kg of sodium persulfate is dissolved in 8 liters of water; we obtain a set G.

The mixture of the two sets forms a grout whose setting time is 8 minutes at 10 ° C; it is particularly suitable for injection into a volume containing water and coarse alluvium.

EXAMPLE 10

On the one hand, to 92 liters of commercial solution of ROCAGIL AL6, 500 g of triethanolamine in 500 g of ethylene glycol and then 100 kg of barium sulphate are added; we obtain a set H.

On the other hand, 1 kg of sodium persulfate is dissolved in 8 liters of water; we obtain a set I.

The mixture of the two sets forms a viscous and dense grout, the setting time of which is 15 minutes at 10 ° C; it is particularly suitable for injection into a volume containing water with high circulation.

EXAMPLE 11

On the one hand, 20 liters of commercial solution of ROCAGIL BT (methylolacrylamide-based solution marketed by Rhône-Poulenc), 0.1 kg of triethanolamine in 0.1 kg of ethylene glycol; we obtain a set J.

On the other hand, 0.2 kg of sodium persulfate is dissolved in 20 liters of water and then 60 kg of plaster are introduced; we obtain a set K.

The mixture of the two sets forms a grout whose setting time at 20 ° C is 6 minutes; the material obtained is capable of swelling in water and has good mechanical properties under compression; the grout is particularly suitable for injection into a volume containing water with high circulation.

EXAMPLE 12

On the one hand, 100 liters of an aqueous solution of silica smoke containing 50% dry matter are added to 92 liters of ROCAGIL AL6; we obtain a set L.

On the other hand, 0.5 kg of sodium persulfate is dissolved in 8 liters of water; we obtain a set M.

The mixture of the two sets forms a grout capable of swelling with water, the setting time of which is 25 minutes at 20 ° C; it is particularly suitable for injection into a volume containing water and coarse alluvium.

Claims (5)

1. A process for sealing sheet-pile walls by introducing into the empty space between the complementary locked bends of said walls a fluid system capable of forming at the temperature obtaining in the interior of said space a gel occupying the volume of said space by swelling in contact with an aqueous medium present in the zone to be sealed off, characterised in that the fluid system has a viscosity of less than 15 Pa.s and is formed by:

   - an ethylenically unsaturated substance which is diluted in water and which by polymerisation and/or cross-linking is capable of forming a solid gel or resin,

   - a polymerisation and/or cross-linking initiator, and

   - an agent which swells in an aqueous medium when the gel or resin formed does not swell or does not swell sufficiently of its own accord in contact with the aqueous medium present in the zone to be sealed off,

   the setting time of said system being less than about 1 hour.
2. A process according to claim 1 characterised in that the fluid system is an aqueous system form by:

   - a polymer which is soluble or dispersible in water and capable of forming by cross-linking an elastic gel or resin,

   - an agent for cross-linking of said polymer,

   - and if necessary an agent which swells in contact with water.
3. A process according to claim 1 or claim 2 characterised in that the fluid system is an aqueous system formed by:

   - an aminoplastic resin,

   - a hardening agent of acid type,

   - and if necessary an agent which swells in contact with water.
4. A process according to one of claims 1 to 3 characterised in that, after mixing of its different constituents, the fluid system is injected under pressure into the empty space between the complementary locked bends.
5. Use of a process according to any one of claims 1 to 4 for sealing sheet-pile walls with respect to aqueous media.