Binder Composition for Improved Mortars and Coatings

Abstract

A binder composition for enhanced mortars and coatings, comprising a first conventional mineral component and a second component based on powdery slaked lime, wherein said second component based on powdery slaked lime has a specific surface area calculated according to the BET method of less than 12 m.sup.2/g, advantageously less than 11 m.sup.2/g, in particular less than 10 m.sup.2/g, preferably less than 9 m.sup.2/g and its uses as well as the enhanced coating or mortar systems comprising an aggregate of the mineral type and the aforesaid composition.

Claims

1. A composition for enhanced mortars and coatings, comprising a first conventional mineral component and a second component based on powdery slaked lime, wherein said second component based on powdery slaked lime has a specific surface area calculated according to the BET method of less than 12 m.sup.2/g.

2. The binder composition according to claim 1 wherein said second component has a specific surface area calculated according to the BET method of less than 8.5 m.sup.2/g.

3. The binder composition according to claim 1, wherein said first conventional mineral component is selected from the group consisting of cements, of standard slaked or air lime, of natural or artificial hydraulic lime, of masonry binders, of pozzolanic and hydraulic binders, gypsum and mixtures thereof.

4. The binder composition according to claim 3, wherein said cement is selected from the group consisting of common cements, refractory cements, molten aluminous cements, prompt cements, Portland cements, slags from blast furnaces, fly ash and mixtures thereof.

5. The binder composition according to claim 1, wherein said second component is present in an amount equal to or greater than 12% by weight and equal to or less than 80% by weight, based on the total weight of said binder composition.

6. The binder composition according to claim 1, wherein said second component has particles having a d3 greater than 0.1 m and a d98 of less than or equal to 250 m.

7. The binder composition according to claim 1, wherein said second component has particles having a d93 of less than or equal to 90 m.

8. The binder composition according to claim 1, wherein said second component based on powdery slaked lime has a total pore volume calculated according to the BJH method of nitrogen desorption greater than or equal to 0.02 cm.sup.3/g.

9. The binder composition according to claim 1, wherein said second component based on powdery slaked lime has a total pore volume calculated according to the BJH method of nitrogen desorption of less than or equal to 0.07 cm.sup.3/g.

10. The binder composition according to claim 1, further comprising an air entrainer comprising a surfactant or tenside, in particular selected from the group consisting of alkyl sulfates or sulfonates, ethoxylated fatty alcohols, block copolymers and mixtures thereof.

11. The binder composition according to claim 1, further comprising one or several water retaining agents, selected from the group consisting of cellulose ethers or guar gums, derivatives thereof and mixtures thereof.

12. The binder composition according to claim 1, further comprising a rheology modifier comprising a hydrocolloid, and more particularly being selected from the group consisting of polysaccharides, starch derivatives, alginates, guar gums and derivatives thereof, xanthan gums and derivatives thereof, carrageenan gums and derivatives thereof, succinoglycans, superplasticizers including polycarboxylates and melamine formaldehydes, and mineral colloids, in particular selected from the group consisting of silica and clays, and mixtures thereof.

13. The composition according to claim 1, further comprising a hydrophobicizing agent selected from the group consisting of salts of fatty acids including stearates and oleates, vegetable and mineral oils, silanes, siloxanes and mixtures thereof.

14. The composition according to claim 1, further comprising a third organic component comprising an industrial latice selected from the group consisting of copolymers based on polyvinyl acetate/ethylene, on polyvinyl acetate/versatate, styrene/butadiene.

15. The composition according to claim 1, wherein said second component based on slaked lime has a bulk density measured according to the EN 459 2 standard of more than 350 kg/m.sup.3.

16. A system of enhanced coatings or mortars comprising an aggregate of the mineral type and the composition according to claim 1.

17. The system according to claim 16, characterizing that it is in a dry form, ready to be mixed with water.

18. The system according to claim 16, further comprising water and thus being in a ready-to-use form.

19. The system according to claim 16, further comprising an air entrainer comprising a surfactant or tenside, in particular selected from the group consisting of alkyl sulfates or sulfonates, ethoxylated fatty alcohols, block copolymers and mixtures thereof.

20. The system according to claim 16, further comprising one or several water retaining agents, including cellulose ethers or guar gums, derivatives thereof and mixtures thereof.

21. The system according to claim 16, further comprising a rheology modifier which comprises a hydrocolloid, and more particularly selected from the group consisting of polysaccharides, starch derivatives, alginates, guar gums and derivatives thereof, xanthan gums and derivatives thereof, carrageenan gums and derivatives thereof, succinoglycans, superplasticizers including polycarboxylates and melamine formaldehydes, and mineral colloids including silica and clays, and mixtures thereof.

22. The system according to claim 16, further comprising a hydrophobicizing agent which comprises the salt of a fatty acid, the hydrophobicizing agent being selected from the group consisting of stearates and oleates, vegetable and mineral oils, silanes, siloxanes and mixtures thereof.

23. The system according to claim 16, further comprising a third organic component which comprises an industrial latice the industrial lattice being selected from the group consisting of latices based on polyvinyl/ethylene, polyvinyl acetate/versatate, styrene/butadiene copolymers.

24-26. (canceled)

Description

[0065] Other features, details and advantages of the invention will become apparent from the description given hereafter, as non-limiting and with reference to the examples.

EXAMPLES

Example 1

Impact of Hydrated Lime with a Low Specific Surface Area in a Coating

[0066] The binder composition for a coating with high added value mentioned in table 1 was prepared with the following components and in the indicated proportions:

TABLE-US-00001 TABLE 1 Proportion Products (% by weight) Cement CEM I 42.5 R 51% Hydrated lime 47% Redispersible latex powder (Vinnapas 0.4% 8031 H) Water retainer (Tylose MH 15000 YP4) 0.5% Air entrainer (Hostapur OSB) 0.1% Hydrophobicizer (Zinkum 5) 1%

[0067] In this formulation, a lime with a high specific surface area (HS) is compared with two limes of low specific surface area (BS), and a standard lime (STD) of a standard specific surface area, according to table 2.

[0068] By the expression of specific surface area used in the present invention, is meant the specific surface area measured by nitrogen adsorption manometry and calculated according to the Brunauer, Emmett and Teller model (BET method), after degassing in vacuo at 190 C. for at least 2 hours.

TABLE-US-00002 TABLE 2 Product BET surface area (m.sup.2/g) BJH pore volume (cm.sup.3/g) Lime HS 45.1 0.24 Lime STD-1 15.9 0.08 Lime BS1 8.4 0.04 Lime BS2 7.2 0.04

[0069] A coating is prepared starting from the aforementioned binder by adding siliceous sand, so as to obtain the bulk composition mentioned in table 3.

TABLE-US-00003 TABLE 3 Proportion (% by Products weight) Cement CEM I 42.5 R 13% Hydrated lime 12% Reidispersable latex powder (Vinnapas 0.1% 8031 H) Water retainer (Tylose MH 15000 YP4) 0.12% Air entrainer (Hostapur OSB) 0.02% Hydrophobicizer (Zinkum 5) 0.3% Siliceous sand (0.1-0.6 mm) 74.5%

[0070] The mixing rate of the fresh coating (water/Solid, W/S) according to table 3 is adjusted in order to obtain a consistency (slump) of the slurry of 1755 mm according to the EN1015-3 standard. The characteristics of the coatings are mentioned in table 4. The density of the fresh coating and the entrained air are evaluated according to the EN1015-6 and EN1015-7 standards. Water retention is evaluated with a device according to the ASTM C91 standard with a negative pressure of 7,000 Pa for 15 min, with the same consistency of the slurry (slump of 1755 mm). Only the water retention value after 15 min is shown.

TABLE-US-00004 TABLE 4 A coating Slump Air Water retention based on W/S[%] [mm] Density [%] 15 min [%] Lime HS 28.4 178 1.7 14 92 Lime STD- 21.5 177 1.6 18 94 1 Lime BS1 21.3 170 1.5 22 95 Lime BS2 20.4 175 1.5 24 96

[0071] As this may be seen, coatings based on lime with a low specific surface area (BS) have a lower water demand (W/S). It is well known that a low water demand lowers the risk of shrinkage and cracks in the coating, and increases the mechanical strength of a formulation including a hydraulic binder.

[0072] It is also observed that lime with a low specific surface area give the possibility to the organic additives of better fulfilling their role of an air entrainer or water retainer. A higher air level gives the fresh coating better plasticity/handling capability, increases its yield, as well as the isolating power and the resistance to freezing/thawing cycles of the hardened coating. Better retention of water of the fresh coating increases its tolerance towards variable supports, and of high porosity.

[0073] Let us note that an increase in the water retention beyond 92% is typically very delicate to obtain while maintaining good handling capability. This strong water retention is further highly sought by one skilled in the art.

Example 2

Impact of Hydrated Lime with Low Specific Surface Area in an Enhanced Masonry Mortar (II)

[0074] The binder composition for a masonry mortar mentioned in table 5 was prepared with the following components and in the indicated proportions:

TABLE-US-00005 TABLE 5 Products Proportion (% by weight) Cement CEM I 42.5 N 84.4% Slaked lime 15.4% Air entrainer (Hostapur OSB) 0.1% Water retainer (Tylose MH 15003 P6) 0.1%

[0075] In this formulation, a lime with low specific surface area (BS) is compared with a standard lime (STD) with standard specific surface area according to table 6:

TABLE-US-00006 TABLE 6 Product BET Surface (m.sup.2/g) BJH pore volume (cm.sup.3/g) Lime STD-3 15.2 0.08 Lime BS2 7.2 0.04

[0076] An enhanced masonry mortar is prepared starting with the aforementioned binder by adding siliceous sand, so as to obtain the bulk composition mentioned in table 7:

TABLE-US-00007 TABLE 7 Proportion (% by Products weight) Cement CEM I 42.5 N 11% Slaked lime 2% Limestone filler 11% Air entrainer (Hostapur OSB) 0.01% Water retainer (Tylose MH 15003 P6) 0.01% Siliceous sand (0.1-1.2 mm) 76%

[0077] The mixing level of the fresh mortar (Water/Solid, W/S) according to table 5 is adjusted in order to obtain a consistency (slump) of the slurry of 1755 mm according to the EN1015-3 standard. The characteristics of the mortars are mentioned in table 8.

[0078] The density of the fresh mortar and the entrained air are evaluated according to the EN1015-6 and EN1015-7 standards.

[0079] Water retention is evaluated with a device according to the ASTM C91 standard with a negative pressure of 7,000 Pa for 15 min, with the same consistency of the slurry. Only the water retention value after 15 min is shown.

TABLE-US-00008 TABLE 8 Retention of Mortar based W/S Slump Air water 15 min on [%] [mm] Density [%] [%] Lime STD- 14.1 173 1.8 18.0 72 3 Lime BS2 13.7 176 1.6 25.0 75

[0080] Again, the lime with low specific surface area (BS) allows the air entrainer and the water retention additive to better fulfill their role with the possibility of optionally reducing their level in the composition or increasing water retention for an equal amount of additives. According to this example, the impact on the air entraining is particularly pronounced and interesting, the impact on the water retention finally being limited because of the low content of water retention additive.

[0081] Of course the present invention is by no means limited to the embodiments described above and that many modifications may be provided thereto without departing from the scope of the appended claims.