EP2046694A1

EP2046694A1 - Hydrated calcium silicate part and composition, and process for manufacturing said hydrated calcium silicate part

Info

Publication number: EP2046694A1
Application number: EP07823549A
Authority: EP
Inventors: Pablo Ignacio Comino Almenara; Anne-Laure Beaudonnet; Axel De Lavernhe
Original assignee: OCV Intellectual Capital LLC
Current assignee: Owens Corning Intellectual Capital LLC
Priority date: 2006-07-06
Filing date: 2007-07-05
Publication date: 2009-04-15
Also published as: CN101484402A; JP2009542464A; FR2903401B1; FR2903401A1; WO2008003906A1

Abstract

The invention relates to an extruded part based on alkali-resistant glass fibres in hydrated calcium silicate obtained essentially by the reaction of slaked lime and silica having a particle size defined by the parameter D<SUB>50</SUB> of 100 µm or less. The invention furthermore relates to an extrudable composition comprising free water, silica with a particle size defined by the parameter D<SUB>50</SUB> of 100 µm or less, slaked lime, alkali-resistant glass fibres, a plasticizer and a cohesion agent. The invention also relates to a process for manufacturing a part based on alkali-resistant glass fibre and hydrated calcium silicate, said process comprising extrusion of the composition, the predrying of the fresh part and the autoclaving of the predried part at a temperature of above 150°C.

Description

PIECE AND COMPOSITION IN HYDRATED CALCIUM SILICATE,

PROCESS FOR MANUFACTURING CALCIUM HYDRATE SILICATE PIECE

The present invention relates to a hydrated calcium silicate component, a hydrated calcium silicate composition and a method for manufacturing a hydrated calcium silicate component.

Hydrated calcium silicate thermal insulation panels (commonly known as CSH for calcium silicate hydrates in English) are already known. Such products are obtained by molding and autoclaving a water-based composition, generally quick lime (of formula CaO), Portland cement.

The object of the invention is to further broaden the range of hydrated calcium silicate products by providing products which are both efficient, easy and / or quick to manufacture, even on an industrial scale, and inexpensive. For this purpose, the invention firstly proposes an extruded part based on alkali resistant glass fibers in hydrated calcium silicate obtained essentially by reaction of silica, with a particle size defined by the parameter D50 less than or equal to 100 μm, and slaked lime, otherwise known as calcium hydroxide, of formula Ca (OH) ₂ . The part according to the invention is extruded. Extrusion makes it possible to manufacture complex, hollow or solid parts and composite parts. The piece may be of elongated shape, in particular form a profile, have a section of any shape (square, rectangular, oval, U, T, with one or rounded edges etc).

Furthermore, it is chosen to strongly limit, and preferably to eliminate the use of cement. Thus, the part may comprise as siliceous source at least 90% of silica, preferably 95%, even more preferably 100% of silica (single siliceous source), the hydrated calcium silicate is then obtained solely by reaction of the silica and the silica. slaked lime.

The use of a silica makes it possible to further control the type of calcium silicate hydrate obtained, in particular to increase the crystalline phases at the expense of the hydrated calcium silicate gel, for greater durability. The type of crystalline structure is related to the autoclaving heat treatment.

The silica dosage is also easier to control than with a cementitious composition whose formulation is often poorly known. Silica is also an inexpensive raw material that is easy to obtain. In particular, the silica may be industrial, for example milled, micronized sand.

Moreover, to obtain satisfactory mechanical properties, fine silica is chosen whose D50 parameter is less than or equal to 100 μm rather than the standard D50 sand of the order of mm.

From an aesthetic point of view, the use of silica as essential or even unique siliceous source makes it possible to obtain a white, pigmentable piece that is particularly suitable for decorative or ornamental use. This piece can also have one or more technical functions. Conversely, a cement-based part or even other pozzolans, such as silica fume, fly ash, is usually gray.

The piece according to the invention is suitable indoors and outdoors because it resists atmospheric aggression (including rain, sun, ultraviolet). The piece also retains the fire resistance and insulation properties attributed to hydrated calcium silicate.

The mineral matrix used during the production of the part being very alkaline, typically of pH greater than or equal to 13, alkali-resistant glass fibers (called AR fibers) are chosen. An example of AR glass yarns are CemFIL® and ARcoteX® fibers sold by Saint-Gobain Vetrotex.

AR glass generally contains ZrO 2 zirconium oxide. These yarns may be chosen from all existing "alkali-resistant" glass yarns (such as those described in patents GB 1,290,528, US Pat. No. 4,345,037, US Pat. No. 4,036,654, US Pat. No. 4,014,705 and US Pat. etc.) and preferably comprise at least 5 mol% ZrO 2. According to one embodiment of the invention, the constituent glass of the son comprises SiO 2, ZrO 2 and at least one alkaline oxide, preferably Na 2 O, as main constituents.

An alkali-resistant glass composition particularly used to produce the glass strands according to the invention is the composition described in GB Patent 1,290,528, mainly composed of the following components in the proportions expressed in molar percentages: 62-75% SiO 2; 7-11% ZrO 2; 13-23% R ₂ O; 1-10% R'O; 0-4% AI ₂ O ₃ ; 0-6% B ₂ O ₃ ; 0-5% Fe ₂ O ₃ ; 0-2% CaF ₂ ; 0-4% TiO ₂ ; R ₂ O representing one or more alkaline oxide (s), preferably Na2θ and optionally LJ2O and / or K2O, and R'O being one or more components selected from alkaline earth oxides, ZnO and MnO.

These fibers make it possible to increase the resistance in flexion as in compression. Preferably, dispersible fibers may be chosen to ensure the best possible surface condition.

The extruded part according to the invention is also lighter than a cement-based part. Reported on a surface (or a support), such as a wall or facade surface of a building, it does not constitute a significant overload.

The extruded part according to the invention may preferably have a density of less than 2 g / cm ³ , measurable by hydrostatic weighing. The part may preferably have a porosity of less than or equal to 60%, preferably less than 50%, resulting in a number of defects limited to the core.

In a preferred embodiment, the parameter D50 is less than or equal to 50 μm, more preferably between 10 and 20 μm. These are the optimal ranges for mechanical properties.

Preferably, for better mechanical properties, the extruded part according to the invention may comprise less than 25% of carbonated lime, called calcite and of formula CaCO 3, even more preferably less than 15% and / or may comprise less than 5% of portlandite, of formula Ca (OH) ₂ , even more preferably less than 1% of portlandite.

The extruded part according to the invention may have a Young's modulus preferably greater than or equal to 4 MPa, even more preferably greater than or equal to 6 MPa. The elongation may be of the order of 0.1%. The extruded part according to the invention is dimensionally stable, has a good surface appearance, without blisters, and / or swelling and / or cracks visible to the naked eye. The extruded part according to the invention may comprise at least 1% by weight of dry materials of the glass fibers.

The part according to the invention can confer a particular profile on a surface, in particular an architectural style. For example, it is an element of modeling, a cornice, a frame (door, window), a horizontal strip, a plinth, etc.

The subject of the present invention is also a hydrated calcium silicate composition that is easy to implement, making it possible to new applications.

To this end, the invention also proposes an extrudable composition comprising: free water, silica, with a particle size defined by the D50 parameter less than or equal to 100 μm, slaked lime, resistant alkali glass fibers, plasticizer, a cohesion agent, the mass ratio between the slaked lime and the silica being between 0.7 and 1. The silica and the slaked lime are able to react, in an autoclave, to form hydrated calcium silicate. The reduction of the lime dosage makes it possible to obtain good mechanical properties, in particular by a reduction in carbonate lime.

The mass ratio between the slaked lime and the silica may preferably be of the order of 0.8.

The lime used may be in the form of a dry powder, in the form of whitewash or lime paste. The superplasticizer contributes to the fluidification of the mixture and facilitates the extrusion. It may preferably be of the polynaphthalene sulfonate or polycarboxylate type. Preferably, its level is of the order of 2% by weight.

The cohesion agent makes it possible to guarantee the homogeneity of the matrix. It may be chosen preferably from a water-soluble and non-ionic cellulose ether such as methyl hydroxyethyl cellulose, or hydroxypropylethyl cellulose. Preferably, its level is less than 1% by weight.

The Applicant has discovered that the sand of millimetric granulometry was certainly extrudable but led after autoclaving to a product of too low mechanical strength. Also, a finer silica with a D50 parameter of less than or equal to 100 μm is chosen.

In a preferred embodiment, the parameter D50 is less than or equal to 50 μm, more preferably between 10 and 20 μm. Advantageously, the extrudable composition according to the invention may comprise essentially fine silica as siliceous material for the reasons already invoked for the part.

In addition, so that the formulation is not too firm and dries too fast, the dosage can be adjusted in water and / or plasticizer. For example, the ratio between the quantity of water relative to the quantity of solids is preferably of the order of 0.4 or more and / or the level of plasticizer is of the order of

2% by weight or more.

The slaked lime may comprise at least 90% CaO. Lime is whiter than it is pure. We prefer the lime flower.

The subject of the present invention is furthermore a process for manufacturing a part based on alkali-resistant glass fiber and hydrated calcium silicate comprising the following steps: extruding the composition defined above to form a so-called fresh piece, -Drying the cool room, autoclaving the pre-dried part to a temperature higher than 150 ⁰ C, preferably greater than or equal to 180 ⁰ C, more preferably of the order of 200 ° C.

The pre-drying makes it possible to evacuate the free water for use which does not intervene in the hydration reaction and to dimensionally stabilize the extruded composition.

Direct autoclaving is likely to generate defects in aspects: swelling, cracks that weaken the room and degrade the mechanical strength.

Preferably, sufficient pre-drying is performed to remove the maximum of the free water, preferably to have about 15% mass loss, ie between 13 and 16%. If the loss of mass is higher, for example of the order of 22%, the mechanical performance is lower because it is likely that not only the free water is consumed but probably also some of the water needed to hydration. A loss of mass of 22% is obtained for example for a drying time of 96 hours at room temperature or 24 hours at 60 ^° C. There is thus an optimum for the duration of the pre-drying at a given temperature. The mechanical performances obtained are lower when the pre-drying time is shortened because a part with defects is obtained (a too abrupt start of the water) but conversely an excessive pre-drying time leads to a carbonation of lime at the expense of the durability of the room.

In a preferred embodiment, the pre-drying is carried out at ambient temperature for a period of between 48 hours and 72 hours, which leads to a mass loss of 14%. Underwater polishing type surface treatment can be carried out using silicon carbide abrasive paper.

Other details and advantageous features of the invention appear on reading the following Examples 1 to 4.

Example 1

In a mixer, a composition thus formulated is kneaded:

34.3% by weight of slaked lime of greater than 90% purity, such as the Lhoist Boran lime, - 34.3% by weight of fine silica dry powder, such as silica S10 from Sifraco , whose parameter D50 is equal to 17 μm, 28.5% by weight of water,

1, 4% by weight of a plasticizer, of the polynaphthalene sulfonate type, such as Lomar D from Cognis, - 0.5% by weight of a cohesion agent chosen from a water-soluble and nonionic cellulose ether such as methyl hydroxyethyl cellulose, for example Culminai MHEC 15000 from Aqualon, 0.9% by weight of alkali-resistant glass fibers (ie 1.35% relative to the amount of solids), for example dispersible fibers called Cemfil "70/30" 6, 9 or 12 mm in length and sold by the company Saint-Gobain Vetrotex, or alternatively Cemfil type fibers "62/2" sold by the company Saint-Gobain Vetrotex. Preferably, the lime, the silica and the fibers are first kneaded dry and at a low speed, the water and the adjuvants are then added and kneaded at a higher speed.

This composition is extruded, preferably at higher speed to avoid the appearance of defects. Different shapes of dies are chosen to produce pieces of varied geometry: plate, L-shaped profile, profile with at least one rounded edge.

Pre-drying of the fresh 72 hour extrudate at 35 ° C is performed to remove the free water as much as possible.

The dried part is then autoclaved under 15 bar at 204 ^° C.

The piece is free of cracks, swelling, is dimensionally stable.

Finally, a water polishing type surface treatment is carried out using a silicon carbide abrasive paper to obtain a smooth surface.

An X-ray diffraction analysis of the part makes it possible to identify the different phases and to quantify them as shown in Table 1:

Table 1

It appears that lime and silica react to form crystallized (tobermorite) or amorphous hydrated calcium silicates (CSH gel). The autoclaving temperature being greater than 150 ^° C., the CSH gel tends to crystallize to form tobermorite crystals. Calcite, which can be a source of weakness, is limited in quantity and no portlandite is detected.

The extruded part is white, light. Its density, measured by hydrostatic weighing, is equal to about 1.7 g / cm ³ . Its porosity according to the standard ASTM C642-90 is in addition of the order of 47%, reflecting the absence of defects within the matrix.

Mechanical performance is evaluated by a 4-point bend test on extruded test pieces in accordance with EN 1170-5. The tests are carried out with a ZWICK1474 press on specimens measuring 85 mm × 350 mm and having a thickness of 20 mm. The speed of servocontrolling motion is 2 mm / min, the upper center distance 83 mm and the lower center distance 250 mm. The Young's modulus is of the order of 6.5 MPa and the elongation of 0.08%.

Example 2

The formulation of Example 1 is modified to further facilitate extrusion. The water dosage is increased to 29% and the plasticizer dosage is increased to 2%.

An X-ray diffraction analysis of the extruded part makes it possible to identify the different phases and to quantify them as shown in Table 2:

Table 2

Calcite is present in greater proportion and tobermorite is very minor. The Young's modulus is of the order of 4.3 MPa and the elongation of 0.08%. The mechanical performances obtained are acceptable but nevertheless lower than for example 1. The extruded part remains white, light, free of cracks, swelling, dimensionally stable.

Density and porosity are unchanged from Example 1.

Example 3

To further improve the mechanical performance of the part shown in Example 2, the pre-drying time has been optimized. The best mechanical performances are obtained with a pre-drying of 48 hours at

35 ° C leading to a loss of mass of the order of 14%. The Young's modulus then reaches 5.2 MPa and the elongation is 0.06%.

The extruded part remains white, light, free of cracks, swelling, dimensionally stable. Its density and porosity are unchanged.

Example 4

The formulation of Example 1 is modified: the plasticizer dosage is increased to 2% to further facilitate the extrusion and the mass ratio slaked lime on silica was adjusted. More specifically, the slaked lime dosage is decreased to a ratio of 0.8 (30.3% slaked lime on 37.9% silica).

An X-ray diffraction analysis of the extruded part makes it possible to identify the different phases and to quantify them as shown in Table 3:

Table 3 The reduction of the lime-slaked dosage significantly improves the mechanical performance. The proportion of calcite, which can be a source of weakness, is limited. Most of the slaked lime is thus combined with the silica to form hydrated calcium silicates (as amorphous or crystallized gel). The Young's modulus is high, of the order of 6.9 MPa and the elongation of 0.1%.

The extruded part remains white, light, free of cracks, swelling, dimensionally stable. Its density and porosity are unchanged. The extruded parts described in Examples 1 to 4 are particularly suitable as decorative pieces, ornamental or architectural, especially as elements of modeling, cornices, frames, or skirting boards.

Claims

1. Extruded part based on resistant alkali glass fibers in hydrated calcium silicate obtained essentially by reaction of slaked lime and silica having a particle size defined by the D50 parameter less than or equal to 100 microns.

2. Extruded part according to the preceding claim characterized in that the calcium silicate hydrate is obtained solely by reaction of silica and slaked lime.

3. Extruded part according to one of the preceding claims characterized in that the parameter D50 is less than or equal to 50 microns, preferably between 10 and 20 microns.

4. Extruded part according to one of the preceding claims characterized in that it has a density less than 2 g / cm ³ .

5. Extruded part according to one of the preceding claims characterized in that it has a porosity of less than 60%, preferably less than or equal to 50%.

6. Extruded part according to one of the preceding claims characterized in that it has a Young's modulus greater than or equal to 4 MPa, preferably greater than or equal to 6 MPa.

7. extruded part according to one of the preceding claims characterized in that it comprises less than 25% of carbonate lime and / or it comprises less than 5% portlandite.

8. Extruded part according to one of the preceding claims characterized in that it forms a profile.

9. Extruded part according to one of the preceding claims characterized in that it is a decorative piece, ornamental or architectural, including at least one of the following parts: a molding element, a cornice, a frame, a plinth.

10. Extrudable composition comprising: free water, silica, with a particle size defined by the D50 parameter less than or equal to 100 μm, - slaked lime,

alkali resistant glass fibers,

a plasticizer,

- a cohesive agent. the mass ratio between the slaked lime and the silica being between 0.7 and 1.

11. extrudable composition according to the preceding claim characterized in that the mass ratio between the slaked lime and silica is of the order of 0.8.

12. extrudable composition according to one of claims 10 or 11 characterized in that the parameter D50 is less than or equal to 50 microns, preferably between 10 and 20 microns.

13. extrudable composition according to one of claims 10 to 12 characterized in that the composition comprises essentially as siliceous material said silica.

14. extrudable composition according to one of claims 10 to 13 characterized in that the slaked lime comprises at least 90% of CaO.

15. Extrudable composition according to one of claims 10 to 14 characterized in that the plasticizer is of the polynaphthalene sulfonate or polycarboxylate type and preferably the plasticizer content is of the order of 2% by weight.

16. Extrudable composition according to one of Claims 10 to 15, characterized in that the cohesion agent is chosen from a water-soluble and non-ionic cellulose ether such as methyl hydroxyethyl cellulose or hydroxypropylethyl cellulose, preferably at least one less than 1% by weight.

17. A method of manufacturing an alkali resistant fiberglass-based part and hydrated calcium silicate comprising the following steps: extruding the composition according to one of claims 10 to 16 to form a fresh part; drying the fresh part, autoclaving the pre-dried part at a temperature above 150 ^° C.

18. The manufacturing method according to the preceding claim characterized in that the pre-drying is such that the loss of mass is of the order of 15%.

19. The manufacturing method according to one of claims 17 or 18 characterized in that the pre-drying is performed at ambient atmosphere for a period between 48 hours and 72 hours.