EP3131860A1

EP3131860A1 - Composite material especially for repairing water tanks

Info

Publication number: EP3131860A1
Application number: EP15721138.4A
Authority: EP
Inventors: Jean Ambroise; Marie Michel
Original assignee: Universite Claude Bernard Lyon 1 UCBL; Institut National des Sciences Appliquees de Lyon
Current assignee: Universite Claude Bernard Lyon 1 UCBL; Institut National des Sciences Appliquees de Lyon
Priority date: 2014-04-18
Filing date: 2015-04-17
Publication date: 2017-02-22
Also published as: WO2015158891A1; FR3020057A1

Abstract

The invention relates to a mineral matrix comprising an ettringite binder, a granular backbone, and additives, said additives comprising a tackifier, in particular a polyvinyl alcohol.

Description

COMPOSITE MATERIAL, IN PARTICULAR FOR THE REPAIR OF

WATER RESERVOIR

TECHNICAL AREA

The invention relates to the general technical field of composite materials of reinforced concrete type textile (or "TRC", acronym of the English expression "Textile Reinforced Concrete"). More specifically, the present invention relates to a mineral matrix that can be combined with a technical textile to form a mineral matrix composite.

Such a mineral matrix composite can be used in many structural applications of construction or civil engineering rehabilitation, such as water tank repair.

PRESENTATION OF THE PRIOR ART

Many composite materials have been developed in the Civil Engineering sector to allow the design or rehabilitation of works or parts of work.

Composite materials are particularly suitable for reinforcing, protecting, maintaining and repairing existing structures because of:

- their mechanical performances, in particular in traction,

- their lightness (which does not overload the structure being repaired) and

- their adhesion to concrete or masonry.

Composites are already used for water tank repair. Such composites are based on the combination of an epoxy resin with a technical textile.

The epoxy resin has the advantage:

- stick and adhere to the technical textile, to form a slightly water-repellent plasticized film.

The new legislation concerning products containing bisphenol will result in the requirement to find a matrix of substitution for epoxy resin in composites intended for the repair of drinking water tanks.

WO 03/091179 discloses a dense mortar comprising an ettringite binder, siliceous sands, lime and / or Portiand Cement, powdered polymers, and additives.

Document XP000401603 composite material including an organo-mineral binder composed in particular of Portiand cement and epoxy resin. WO 2013/079877 discloses a mortar comprising a binder composed mainly of Portiand cement. An object of the present invention is to provide a mineral matrix of substitution to the epoxy resin whose properties are compatible with the repair of drinking water tanks.

SUMMARY OF THE INVENTION

For this purpose, the invention proposes a mineral matrix - for example dedicated to the rehabilitation of a structure and in particular to the repair of a water reservoir - comprising a binder, a granular skeleton, and additives, remarkable in that:

the binder is an ettringitic binder, and in that

the additives comprise an adhesion-reinforcing agent, said adhesion-reinforcing agent being a polyvinyl alcohol.

In the context of the present invention, the term "ettringite binder" is intended to mean a binder whose main hydrate is ettringite, unlike, in particular, binders composed mainly of Portiand cement whose main hydrate is calcium silicate hydrate (CSH). ). The ettringitic binder has the particularity of not releasing lime during its hydration. The documents XP000401603 and WO 2013/079877 do not describe a mineral matrix as defined above. Indeed, the binder described in XP000401603 is an organomineral binder composed of Portland cement and epoxy resin. Moreover, the binder described in WO 2013/079877 is mainly composed of Portland cement, so that the main hydrate formed during its hydration is hydrated calcium silicate (CSH), unlike an ettringitic binder.

The use of an ettringitic binder combined with the use of polyvinyl alcohol provides a mineral matrix capable of replacing epoxy resins for water tank repair. Indeed, the combined uses of an ettringitic binder and of polyvinyl alcohol make it possible to obtain a mineral matrix:

- applicable on a technical textile,

having a curing time which is sufficiently short to limit the phenomenon of desiccation,

- adhering to vertical supports.

Advantageously, the ettringitic binder according to the invention comprises:

a first species chosen from aluminous cement (CAC) and / or sulpho-aluminous cement (CSA),

a second species selected from calcium sulphate such as plaster and / or gypsum and / or anhydrite, and

a third species chosen from Portland cement and / or calcium hydroxide. The presence, in the ettringite binder, of Portland cement and / or calcium hydroxide serves to ensure a pH of 10 to 12.5, which corresponds to the stability range of ettringite.

WO 03/091 179 does not disclose an ettringite binder comprising Portland cement and / or calcium hydroxide. On the contrary, WO 03/091 179 dissuades the skilled person from using an ettringitic binder composed of Portland cement or calcium hydroxide (see page 5 lines 30-32 of WO 03/091 179). Of course, the proportions of the third species (Portland cement and / or calcium hydroxide) are chosen so that the hydrated matrix is devoid of Portlandite (ie lime released during the hydration of the calcium silicates of Portland cement) or of slaked lime.

In particular, the third species may be introduced in the following proportions:

between 0 and 12% by weight of the mineral matrix when the third species is composed of Portland cement, or

- Between 0 and 3% by weight of the mineral matrix when the third species is composed of calcium hydroxide.

The inventors have in fact discovered that these proportions of the third species make it possible to maintain the mineral matrix in the ettringite stability domain while guaranteeing the absence of Portlandite or slaked lime in the concrete (ie hydrated matrix). To define these ranges of Portland cement and lime values, different detection methods can be used to detect the presence of Portlandite or lime in a hydrated matrix. For example, differential thermal analysis can be carried out, the dehydroxylation of hydrated lime or Portlandite being characterized by an endothermic peak between 450 and 550 ° C. Alternatively, the presence of lime and / or Portlandite can be detected by Fourier transform infrared spectrometry, with the hydrated lime or Portlandite being detected by a 3640 cm ^-1 vOH absorption band.

Preferred but non-limiting aspects of the mineral matrix according to the invention are the following:

the ettringitic binder can be composed of:

o aluminous cement (CAC) and / or sulfo-aluminous cements (CSA), the amount of which may be between 5 and 60% by weight of the total mass of the mineral matrix,

o and calcium sulphate such as plaster and / or gypsum and / or anhydrite, and whose amount may be between 2 and 30% by weight of the total mass of the mineral matrix, o and Portland cement whose amount can be between 0 and 12% by weight of the total mass of the mineral matrix, or slaked lime whose amount can be between 0 and 3% by weight of the total mass of the mineral matrix;

the amount of adhesive reinforcement may be between 0.1 and 1% by weight of the total mass of the mineral matrix;

the granular skeleton can be:

o optionally milled silica, and / or

o calcareous filler, and / or

o silica fume, and / or

metakaolin, and / or

o fly ash, and / or

o slag;

the amount of granular skeleton can be between 40 and 90% by weight of the total mass of the mineral matrix;

the additives may comprise a setting-modifying agent chosen from:

o the family of carboxylic acids and associated salts, such as tartaric acid, potassium tartrate, and

sodium gluconate,

o sodium carbonate, potassium sulphate, sodium sulphate, lithium sulphate and lithium salts;

the quantity of setting-modifying agent can be between 0.02 and 1% by weight of the total mass of the mineral matrix;

the additives may comprise a viscosity agent chosen from cellulose ethers, guar gum, Xanthan gum, Welan gum, starch ethers and / or phyllosilicates such as hectorite;

the amount of viscosity agent can be between 0.1 and 1% by weight of the total mass of the mineral matrix;

the additives may comprise a resin chosen from polyvalates polyvinyl acetates and / or acrylic styrene and / or styrene butadiene;

the quantity of resin may be between 1 and 20% by weight of the total mass of the mineral matrix; the additives may further comprise a water-repellent of mass chosen from magnesium stearate and / or sodium oleate;

the quantity of water repellent may be between 0 and 3% by weight of the total mass of the mineral matrix.

DETAILED DESCRIPTION OF THE INVENTION

The mineral matrix according to the invention will now be described in more detail. In the following, the expression "mineral matrix" refers to the initial composition consisting in particular of a mixture of powders, the term "concrete" refers to the mineral matrix mixed with water, the expression "hardened concrete Refers to the concrete once it has solidified. 1. Identification of the functions concerned

The mineral matrix must meet the following objectives:

- have a rheology suitable for the coating of vertical walls and the impregnation by clamping nonwoven and woven reinforcements,

- Have a very short curing time that allows to mobilize the mixing water to hydrate the binder, and which makes it possible to oppose the desiccation of the matrix by the rapid structuring of the binder, this susceptibility to desiccation being caused by the very low thickness / exchange surface ratio,

to meet the requirements of adhesion stress on the support,

- be waterproof.

2. Composition of the mineral matrix

The various constituents of the mineral matrix make it possible to respond to the various functions that the latter must satisfy in the context of the water tank repair. In particular, the mineral matrix comprises a binder, a granular skeleton, and one (or more) additive (s).

2.1 Binder

The binder allows the hardening of the mineral matrix. The binder of the mineral matrix is advantageously an ettringitic binder.

In the context of the present invention, the term "ettringitic binder" is intended to mean a binder whose main hydrate formed is ettringite. One of the properties of an ettringitic binder is that it is adapted to harden and quickly build up resistance, which differentiates it from Portland cements.

An ettringitic binder is a mixture of aluminous cement (CAC), calcium sulphate and Portland cement. Aluminous cement can be replaced by sulpho-aluminous cement (CSA), calcium sulphate can be anhydrite, hemihydrate (alpha plaster or beta) or gypsum or a mixture of two of the three calcium sulphates or even three. Thus, the ettringitic binder is composed of:

- aluminous cement (CAC) and / or sulpho-aluminous cement (CSA),

and calcium sulphate such as plaster and / or gypsum and / or anhydrite,

- and Portland cement. Depending on the nature of the calcium sulphate, the dosage of calcium sulphate will form more or less ettringite. Portland cement is there to ensure a pH of 11 to 12.5, which is the range of stability of ettringite. It is possible to replace Portland cement with calcium hydroxide (slaked lime). An example of a hydration reaction between anhydrite and mono-calcium aluminate is presented to illustrate the formation of ettringite (C6AS3H32):

3CA + 3CS + 38H → C6AS3H32 + 2AH ₃

With: - C: CaO,

- S: SOs,

- H: H2O The use of an ettringitic binder has many advantages, especially vis-à-vis a use of the mineral matrix for the repair of drinking water tank.

Indeed, in the context of drinking water tank repair, the mineral matrix is intended to be applied in thin layers on a technical textile to form the composite.

The critical period of thin layers of mineral matrix is the initial period, and especially the first 24 hours after application of it on the technical textile. During this period, there is competition between the hydration of the binder and the evaporation of the water it contains, the phenomenon of evaporation being all the more critical that the layers are thin and the exchange surface between the mineral matrix and the exterior is important. Portland cements are not suitable for use in a thin layer because their hardening time is too high, which leads to a high evaporation and hydration of the degraded matrix, which induces their desiccation.

Ettringitic binders are the solution to the problem of desiccation because associated with suitable additives, it is possible to obtain very short curing times, and therefore a very rapid structuring of the mineral matrix that will oppose the evaporation of mixing water.

2.2 Granular skeleton

The granular skeleton makes it possible to limit the cracking of the mineral matrix after drying of the latter. The granular skeleton is, for example, optionally milled silica, and / or calcareous filler, and / or silica fume, and / or metakaolin, and / or fly ash, and / or slag.

2.3 Additives

Additives play different roles and improve:

o the fluidity of the mineral matrix when mixed with water to form a concrete (i.e. rheology agent),

o the stability of the mineral matrix when mixed with water to form the concrete (i.e. viscosity agent), and

o the service life of the concrete after drying (i.e. resin),

o the setting time of the concrete by reducing or increasing it (i.e. setting-modifying agent),

o the adhesion of concrete to the technical textile during its application, etc.

The additives may comprise in particular a rheology agent, a setting modifier agent, a viscosity agent, a resin, a water-repellent mass. 2.3.1 Bonding agent

The adhesive reinforcing agent makes it possible to increase the adhesion of the matrix to the wall of the tank to be repaired. The reinforcing agent is advantageously a vinyl alcohol. This allows the mineral matrix to stick on the technical textile.

2.3.2 Tack modifying agent The setting modifying agent is for example an accelerator or a retarding agent for accelerating or delaying the setting of the mineral matrix. The setting modifying agent makes it possible to manage the practical duration of use and the duration of setting of the mineral matrix.

When the setting modifier agent is a retarder, it may be selected from carboxylic acids and associated salts such as tartaric acid, potassium tartrate (salt) and / or sodium gluconate (sugar).

When the setting modifier agent is an accelerator, it may be selected from sodium carbonate, potassium sulfate, sodium sulfate, lithium sulfate, lithium salts.

2.3.3 Viscosity agent

The viscosity agent makes it possible to limit the risks of sedimentation of the mineral matrix once the water has been added thereto to obtain the concrete.

The viscosity agent is for example chosen from cellulose ether, guar gum, Xanthan gum, Welan gum, starch ether and / or hectorite. 2.3.4 Resin

The resin makes it possible to increase the life of the product.

The resin is, for example, polyvinyl versatate acetate and / or acrylic styrene and / or styrene butadiene.

2.3.5 Mass hydrofuae

The water-repellents make it possible to reduce the capillarity of the mineral matrix once it has dried. More specifically, the water repellents make it possible to make the mineral matrix impermeable. The water repellents used in the composition of the mineral matrix may be chosen from magnesium stearate and / or sodium oleate.

3. Summary of the different elements constituting the mineral matrix

As an indication, the various elements that may constitute the mineral matrix alone or in combination are summarized in the table below.

Chemical Nature Constituents

reinforcement

Polyvinyl alcohol

adhesion

Cellulose Ether Agent, Guar Gum, Xanthan, Welan Viscosity, Starch Ether, Hectorite

CAC or CSA

calcium sulphate (anhydrite, hemihydrate,

Binder and / or gypsum)

Portland cement

Lime lime

Silica filler, calcareous filler, silica fume,

(skeleton) metakaolin, fly ash, slag

sodium carbonate, potassium sulphate - Sodium modifiers - lithium, lithium salts, acids

carboxylic acid and salts thereof, gluconate

sodium

Water Repellent Magnesium Stearate, Sodium Oleate polyvinyl acetate versatate, styrene

acrylic, styrene butadiene

The percentages by weight of each of the constituents of the mineral matrix are given as an indication in the table below:

Constituents Proportions

0.1 to 1% adhesion reinforcement

Viscosity agent 0.1 to 1%

CAC and / or CAS 5 at 60%

Calcium sulphate 2 to 30%

Portland cement O at 12%

Slaked lime 0 to 3%

Charges (skeleton) 40 to 90%

Catch Modifiers 0.02 to 1%

Water repellent 0 to 3%

Resins 1 to 20%

4. Examples of composition

Two compositions of mineral matrices are presented below by way of non-limiting example of the mineral matrix according to the invention:

Example 1

Constituents Supplier Name Proportions

Bond Strength Modified Starches Sopaduc 0.1% Viscosity agent RHW 1200 Peramin 0.5%

CAC Fused Kerneos 21%

Calcium sulphate Gypsum Lafarge 7%

Portland cement CEM I 42.5 Lafarge 0.5%

Sibelco Silica 31%

Charges (skeleton)

Limestone filler Omya 34%

Roth 0.4% tartaric acid modifiers

Water-repellent Oleate Na / Stearate Mg Peter Greven 1%

Resins Polyvinyl acetate Momentive 6%

Example 2

Constituents Supplier Name Proportions

Bond Strength Modified Starches Sopaduc 0.1%

Viscosity agent HS30 Lamberti 1%

CAC Fused Kerneos 20%

Calcium sulphate Gypsum Lafarge 7%

Portland cement CEM I 42.5 Lafarge 1 .5%

Sibelco Silica 31%

Charges (skeleton)

Limestone filler Omya 34%

Roth 0.4% tartaric acid modifiers

Water-repellent Oleate Na / Stearate Mg Peter Greven 1%

Resins Polyvinyl acetate Momentive 6%

5. Conclusions

As indicated above, in the context of the application of the mineral matrix according to the invention in thin layers (<2 mm) and layer by layer, the problems to be solved are multiple:

- avoid rapid drying of the matrix at the time of hardening so as not to alter its hydration, - ensure a good connection between the different layers of concrete (in particular three) which are applied successively to twenty-four hours apart,

- provide a tear resistance greater than 3 MPa, and

- avoid the development of fungi.

The use of an ettringitic binder and a polyvinyl alcohol makes it possible to constitute a mineral matrix capable of solving these various problems.

The advantage of this solution is its flexibility which allows an adaptation of the composition of the matrix according to the constraints of the building site.

The reader will have understood that many modifications can be made to the mineral matrix described above without physically going out of the new teachings and advantages described here. Therefore, all such modifications are intended to be incorporated within the scope of the appended claims.

Claims

1. Mineral matrix comprising a binder, a granular skeleton, and additives, characterized in that:

the binder is an ettringitic binder, and in that

The mineral matrix according to claim 1, wherein the ettringitic binder is composed of:

- aluminous cement (CAC) and / or sulpho-aluminous cement (CSA),

and calcium sulphate such as plaster and / or gypsum and / or anhydrite,

- and Portland cement or slaked lime.

The mineral matrix of claim 2, wherein:

the quantity of aluminous cement and / or sulfo-aluminous cement is between 5 and 60% by weight of the total mass of the mineral matrix,

the quantity of calcium sulphate is between 2 and 30% by weight of the total mass of the mineral matrix,

the quantity of Portland cement is between 0 and 12% by weight of the total mass of the mineral matrix,

the quantity of slaked lime is between 0 and 3% by weight of the total mass of the mineral matrix.

4. The inorganic matrix according to any one of claims 1 to 3, wherein the amount of adhesive reinforcement is between 0.1 and 1% by weight of the total mass of the mineral matrix.

The mineral matrix according to any one of claims 1 to 4, wherein the granular skeleton is:

- optionally milled silica, and / or

- calcareous filler, and / or

- silica fume, and / or metakaolin, and / or

- fly ash, and / or

- slag.

The mineral matrix according to any one of claims 1 to 5, wherein the amount of the granular backbone is between 40 and 90% by weight of the total mass of the mineral matrix.

The inorganic matrix of any one of claims 1 to 6, wherein the additives comprise a setting modifier agent selected from:

carboxylic acids and related salts such as tartaric acid, potassium tartrate,

sodium gluconate,

sodium carbonate, potassium sulphate, sodium sulphate, lithium sulphate and lithium salts.

The inorganic matrix of claim 7, wherein the amount of setting modifier is from 0.02 to 1% by weight of the total weight of the mineral matrix.

A mineral matrix according to any one of claims 1 to 8, wherein the additives comprise a viscosity agent selected from cellulose ethers, guar gum, xanthan gum, welan gum, starch ethers and the like. / or phyllosilicates like hectorite.

The inorganic matrix of claim 9, wherein the amount of viscosity agent is 0.1 to 1% by weight of the total weight of the mineral matrix.

1 1. A mineral matrix according to any one of claims 1 to 10 wherein the additives comprise a resin selected from polyvinyl acetate versatate and / or acrylic styrene and / or styrene butadiene.

12. The inorganic matrix of claim 1 1, wherein the amount of resin is between 1 and 20% by weight of the total mass of the mineral matrix.

13. A mineral matrix according to any one of claims 1 to 12, wherein the additives further comprise a water-repellent mass selected from magnesium stearate and / or sodium oleate.

14. The inorganic matrix of claim 13, wherein the amount of water-repellent mass is between 0 and 3% by weight of the total mass of the mineral matrix.