CONCRETE COLOURANTS

Abstract

A method of colouring cementitious building materials such as concrete is disclosed. The method uses flowable, spray-dried, particulate formulations of inorganic pigments prepared using a selection of formulants that do not substantially effect primary ettringite formation. Quantities of the formulations may conveniently be dispensed into a slurry of cement and water by gravimetric or volumetric means.

Claims

1. A flowable, spray dried, particulate formulation suitable for use in colouring cementitious building materials comprising in admixture one or more inorganic pigments, poly(ethylene glycol), hydroxylated amine and polycarboxylic acid.

2. A flowable, spray dried, particulate formulation suitable for use in colouring cementitious building materials consisting essentially of one or more inorganic pigments, poly(ethylene glycol), hydroxylated amine and polycarboxylic acid in admixture.

3. The formulation of claim 1 or 2 where the one or more pigments of the formulation are inorganic pigments selected from the group consisting of: synthetic iron oxides (black, browns, red and yellows); natural iron oxides; chromium oxide; cobalt blue; cobalt green; titanium dioxide and carbon black (concrete grade).

4. The formulation of any one of claims 1 to 3 where the formulation comprises poly(ethylene glycol), polycarboxylic acid dispersant and hydroxylated amine in a 2-6:2-6:1 ratio by weight.

5. The formulation of claim 4 where the formulation comprises poly(ethylene glycol), polycarboxylic acid dispersant and hydroxylated amine in a 2-4:4-6:1 ratio by weight.

6. The formulation of claim 5 where the formulation comprises in admixture poly(ethylene glycol), polycarboxylic acid dispersant and hydroxylated amine in a 3:5:1 ratio by weight.

7. The formulation of any one of claims 1 to 6 where the poly(ethylene glycol) has a median molecular weight in the range 7,000 to 9,000 (PEG 8000).

8. The formulation of any one of claims 1 to 7 where the hydroxylated amine is 2-amino-2-methyl-1-propanol.

9. The formulation of any one of claims 1 to 8 where the polycarboxylic acid is a carboxylated acrylic co-polymer.

10. The formulation of any one of claims 1 to 9 where the polycarboxylic acid is less than 5% by weight of the formulation.

11. The formulation of any one of claims 1 to 10 where the formulation consists essentially of the one or more pigments, the poly(ethylene glycol), the polycarboxylic acid dispersant and the hydroxylated amine in a 45-160:2-6:2-6:1 ratio by weight.

12. The formulation of claim 11 where the formulation consists essentially of the one or more pigments, the poly(ethylene glycol), the polycarboxylic acid dispersant and the hydroxylated amine in a 45-125:2-6:2-6:1 ratio by weight.

13. The formulation of claim 12 where the formulation consists essentially of the one or more pigments, the poly(ethylene glycol), the polycarboxylic acid dispersant and the hydroxylated amine in a 45-110:2-6:2-6:1 ratio by weight.

14. The formulation of any one of claims 1 to 13 where the particles of the formulation are of a hollow doughnut morphology with a median diameter in the range 20 to 150 m.

15. The formulation of claim 14 where the particles of the formulation are of a hollow doughnut morphology with a median diameter of 30 to 50 m.

16. A method of colouring a cementitious building material comprising the step of mixing a formulation of any one of claims 1 to 15 with a cementitious premix.

17. The method of claim 16 where the cementitious premix is hydrated immediately prior to the step of mixing the formulation with the cementitious premix.

18. The method of claim 17 where the cementitious premix is a floor levelling or repair product.

19. An integrally coloured cementitious building material comprising one or more pigments, poly(ethylene glycol), hydroxylated amine and polycarboxylic acid.

20. The cementitious building material of claim 19 where the cementitious building material is concrete.

Description

BRIEF DESCRIPTION OF DRAWING

[0039] FIG. 1. Heat output curves for mortars prepared using cement sourced from Golden Bay (plots 2 and 4) or Holcim (plots 1 and 3) with (plots 1 and 2) or without (plots 3 and 4) the addition of 2% (w/w) of a superplasticiser (CD31).

[0040] FIG. 2. Schematic representation of a single-point discharge configuration of a spray dryer (1) of the type used in the methods described provided with an inlet (2), an outlet (3) and a rotary atomiser (4).

[0041] FIG. 3. Heat output curves for coloured mortars prepared using unformulated pigments and corresponding formulations prepared according to the invention. Heat output curves are shown overlain on the heat output curve for unadulterated cement (Control). All mortars were prepared using cement sourced from Golden Bay.

[0042] FIG. 4. Heat output curves for coloured mortars prepared using unformulated pigments and corresponding formulations. Heat output curves are shown overlain on the heat output curve for unadulterated cement (Control). All mortars were prepared using cement sourced from Holcim.

[0043] FIG. 5. Heat output curves for coloured mortars prepared using unformulated pigments and corresponding formulations prepared according to the invention. Heat output curves are shown overlain on the heat output curve for unadulterated cement (Control), All mortars were prepared using cement sourced from Dricon.

[0044] FIG. 6. Photographs of samples of the hardened cementitious floor levelling product SIKA LEVEL 30 (Sika (NZ) Limited) with (A) and without (B) the addition of colourant.

DETAILED DESCRIPTION

[0045] The hydration of cementitious premixes by the addition of water initiates ettringite formation. This primary ettringite formation is important in the hardening and setting of concrete and is to be distinguished from the delayed ettringite formation associated with damage to hardened concrete. During the first hours of hydration the shape and size of the ettringite crystals is influenced by the composition of the alkaline solution in which the crystals are forming. The hardening and setting of concrete can be monitored by calorimetric methods.

[0046] In addition to their ability to effectively disperse the primary particles of inorganic pigments, the selection of formulants for use in the colouring of concrete must also consider the potentially deleterious effect the presence of the formulants in the alkaline solution will have on primary ettringite formation. The formulants used in cementitious building materials are often observed to influence the characteristics of primary ettringite formation (FIG. 1).

[0047] A deleterious effect on primary ettringite formation is likely to be exacerbated when colouring cementitious premixes formulated for use as rapid setting floor levelling and repair products. These products are designed to find their own levels when installed at a thickness of 3 mm or greater. Once hydrated and poured the cementitious mix hardens and sets rapidly so that it can be walked on within as little as two to three hours. The cementitious premixes used in floor levelling and repair are formulated with specially selected polymers to provide these performance characteristics.

[0048] The invention resides partly in the selection of a combination of formulants that do not have a significant deleterious effect on the hardening and setting of cementitious building materials when mixed with a hydrated cementitious premix. The invention also resides partly in this combination of formulants being compatible with the spray drying of aqueous formulations of the inorganic pigments used in colouring cementitious building materials. The invention permits the formulation of a range of these pigments as flowable granules of uniform density that may be dispensed gravimetrically or volumetrically, thereby facilitating the use of these pigments in colouring cementitious building materials.

[0049] The invention will be illustrated with reference to the use of the combination of a poly(ethylene glycol), a polycarboxylic acid and a hydroxylated amine in the preparation of flowable, spray dried, particulate formulations of inorganic pigments that readily disperse when added to hydrated cementitious premixes. The use of this combination of formulants does not adversely affect the primary ettringite formation as evidenced by no observed deleterious effects on the hardening and setting of the building material.

Preparation of Colourants

[0050] The flowable, spray dried, particulate formulations are prepared by dispersing the pigments in an aqueous solution of the formulants. Dispersions of different pigments may be blended if desired prior to spray drying. A schematic representation of single-point discharge configuration of a spray dryer fitted with a rotary atomiser is provided in FIG. 2.

EXAMPLES

Example 1

[0051] A solution of poly(ethylene glycol) 8,000 g/mol (PEG 8000) in water was prepared at a ratio of 10% (w/w) by dissolving 90 g of the PEG 8000 in 900 g of water with gentle agitation. The solution was then blended with 150 g of a polycarboxylic acid dispersant (RHODOLINE 226/40) and 30 g of a hydroxylated amine (AMP 95). Following homogenisation of the blended mix using a high speed disperser, 3,000 g of green oxide pigment was slowly added with continuous stirring up to 3,000 rpm for a total of 80 minutes to provide a homogenous dispersion. The homogenous dispersion was then spray-dried using a GEA Niro MOBILE MINOR (GEA Process Engineering) equipped with a rotary atomiser (channel wheel, 20,000 rpm) in a single-point discharge configuration and operated at an inlet temperature of 185 C. and outlet temperature of 95 C. A particulate formulation of hollow doughnut morphology with a median particle diameter of 30 m was obtained at a rate of 1.9 Kg/hour (1.2% w/w moisture content) with 52% yield.

Example 2

[0052] A selection of poly(ethylene glycol) 8,000 g/mol (PEG 8000) in water was prepared at a ratio of 6% (w/w) by dissolving 75 g of the PEG 8000 in 1250 g of water with gentle agitation. The solution was then blended with 125 g of a polycarboxylic acid dispersant (RHODOLINE 226/40) and 25 g of a hydroxylated amine (AMP 95). Following homogenisation of the blended mix using a high speed disperser, 2,500 g of red ochre pigment was slowly added to provide a raw homogenous dispersion. The raw homogenous dispersion was then ball-milled for a total of 12 hours to provide a final milled homogenous dispersion. The homogenous dispersion was then spray-dried using a GEA Niro MOBILE MINOR (GEA Process Engineering) equipped with a rotary atomiser (channel wheel, 20,000 rpm) in a single-point discharge configuration and operated at an inlet temperature of 185 C. and outlet temperature of 95 C. A particulate formulation of hollow doughnut morphology with a median particle diameter of 30 m was obtained at a rate of 1.9 Kg/hour (1.2% w/w moisture content) with 52% yield.

[0053] Similar quantities of colourants (Examples 3 to 6) were prepared by methods similar to those employed for the preparation of the colourants of Example 1 and Example 2. Larger quantities of colourants (Examples 7 to 9) were prepared using a GEA Niro VERSATILE-SD 6.3N (GEA Process Engineering).

[0054] The colourant of Example 7 was spray-dried with an inlet temperature of 230 C. and an outlet temperature of 85 C. at a production rate of 23 Kg/h with a pressure nozzle configuration and final moisture content of less than 1.5%.

[0055] The colourant of Example 8 was spray-dried with an inlet temperature of 230 C. and an outlet temperature of 95 C. at a production rate of 55 Kg/h with a pressure nozzle configuration and final moisture content of less than 1.5%.

[0056] The colourant of Example 9 was spray-dried with an inlet temperature of 220 C. and an outlet temperature of 90 C. at a production rate of 60 Kg/h with a pressure nozzle configuration and final moisture content of less than 1.5%.

Example 3

[0057]

TABLE-US-00001 Ingredient (with 300 g water) Quantity (g) Ratio Bluish red iron oxide (R5580) 718.0 160 Poly(ethylene glycol) (PEG 400) 26.0 5.8 Polycarboxylic acid dispersant 26.6 5.9 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 4.5 1

[0058] Example 4

TABLE-US-00002 Ingredient (with 211 g water) Quantity (g) Ratio Dark brown iron oxide (Umber 190) 645.0 53 Fumed silica (Aerosil 200) 3.9 Poly(ethylene glycol) (PEG 400) 50.0 4.0 Polycarboxylic acid dispersant 40.0 3.3 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 12.3 1

[0059] Example 5

TABLE-US-00003 Ingredient (with 390 g water) Quantity (g) Ratio Natural red iron oxide (Kremer 48600) 520.0 75 Fumed silica (Aerosil 200) 3.8 Poly(ethylene glycol) (PEG 400) 16.6 2.4 Polycarboxylic acid dispersant 20.0 2.9 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 7.0 1

[0060] Example 6

TABLE-US-00004 Ingredient (with 275 g water) Quantity (g) Ratio English red light iron oxide (Kremer 40542) 771.0 114 Fumed silica (Aerosil 200) 5.0 Poly(ethylene glycol) (PEG 400) 26.0 3.8 Polycarboxylic acid dispersant 31.0 4.6 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 6.8 1

[0061] Example 7

TABLE-US-00005 Ingredient (with 1431.8 Kg water) Quantity (Kg) Ratio Carbon black 954.5 100 Poly(ethylene glycol) (PEG 8000) 28.6 3 Polycarboxylic acid dispersant 38.2 4 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 9.5 1

[0062] Example 8

TABLE-US-00006 Quantity Ingredient (with 111.6 Kg water) (Kg) Ratio Iron oxide red (Red 5530)(Nubolia) (CAS# 1309-37-1) 450.3 100 Poly(ethylene glycol) (PEG 8000) 13.5 3 Polycarboxylic acid dispersant (RHODOLINE 226/40) 20.1 4.5 Hydroxylated amine (AMP 95) 4.5 1

[0063] Example 9

TABLE-US-00007 Ingredient (with 42.49 Kg water) Quantity (Kg) Ratio Iron oxide red (Red 5530)(Nubolia) 73.4 100 (CAS# 1309-37-1) Iron oxide yellow (Yellow 5021) 39.5 (Bayferrox)(CAS# 51274-00-1) Poly(ethylene glycol) (PEG 8000) 3.39 3 Polycarboxylic acid dispersant 5.08 4.5 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 1.13 1

Comparative Examples

[0064] To evaluate the effect of varying the concentrations and ratios of the ingredients on performance a series of spray-dried colourants were prepared of the following composition:

TABLE-US-00008 TABLE 1 Compositions of a series of spray-dried colourants comprising chrome green oxide as the pigment. Ingredient G1 G2 G3 G4 G5 G6 G7 Poly(ethylene glycol) 6 6 6 6 6 3 14.4 (PEG 8000) Polycarboxylic acid dispersant 1.4 3.6 5 7.5 5 5 6 (RHODOLINE 226/40) Hydroxylated amine 1 1 1 1 5 1 1.2 (AMP 95) The quantities of the ingredients are expressed as a percentage by weight of the pigment.

[0065] Each one of the spray-dried colourants from the series was evaluated by mixing at a rate of 2% (w/w) with a slurry of cementitious building material consisting of 225 g water, 500 g dry sand and 1,000 g ordinary Portland cement.

[0066] Yellowing of the surface of the pigmented building material prepared from colourant G4 indicated an upper limit for inclusion of the ingredient RHODOLINE 226/40 of 5% by weight. The best handling and performance characteristics were observed for colourants G1 and G5 indicating a preferred ratio by weight of the ingredient RHODOLINE 226/40 to AMP-95 of around 1.

[0067] Other ingredients were evaluated as alternatives to the use of poly(ethylene glycol) as a formulant. As before batches of trial formulations were spray-dried using either the GEA Niro MOBILE MINOR (GEA Process Engineering) or a Mini Spray Dryer B-290 (Buchi). Spray-drying parameters were optimised for each trial formulation. The ingredients employed in these other formulations and observations concerning the performance of the product of spray-drying are provided as comparative examples only and are not embodiments of the invention.

Comparative Example 1

[0068]

TABLE-US-00009 Ingredient (with 114.6 g water) Quantity (g) Yellow iron oxide (pigment code PY42) 91.3 (CAS# 51274-00-1) Sodium silicate 2.1 Polycarboxylic acid dispersant 0.6 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 0.4

[0069] The formulation was spray-dried using the Mini Spray Dryer B-290 (Buchi) with an inlet temperature of 180 C. and an outlet temperature of 105 C. The product of spray-drying would not disperse when added to an aqueous slurry of concrete. This was attributed to a surface layer of sodium silicate not hydrating rapidly enough to release the primary particles of pigment.

Comparative Example 2

[0070]

TABLE-US-00010 Ingredient (with 1258.1 g water) Quantity (g) Yellow iron oxide (pigment code PY42) 1979.7 (CAS# 51274-00-1) Titanium dioxide 1979.7 682 5.5 Polydextrose 407.0 Polycarboxylic acid dispersant 36.0 (RHODOLINE 226/40) Hydroxylated amine (AMP 95) 10.7

[0071] The formulation was spray-dried using the GEA Niro MOBILE MINOR with an inlet temperature of 180 C., an out let temperature of 95 C. and a spindle speed of 15,000 rpm. The product of spray-drying was mixed at a rate of 3% (w/w) with a slurry of cement (1:2 (w/w) water-cement) comprising no aggregate. Hydration of the cementitious mix was found to be indefinitely retarded.

Comparative Example 3

[0072]

TABLE-US-00011 Ingredient (with 150 g water) Quantity (g) GO 200 Polyvinyl alcohol (MONOSOL) 12 Polycarboxylic acid dispersant (RHODOLINE 226/40) 9 Hydroxylated amine (AMP 95) 3

[0073] The formulation was spray-dried using the Mini Spray Dryer B-290 (Buchi) with an inlet temperature of 180 C. and an outlet temperature of 105 C. The product of spray-drying was mixed at a rate of 4% (w/w) with a slurry of cement (1:2 (w/w) water-cement). Product prepared with either of the trade name products MONOSOL 8900 or MONOSOL BP-3 both displayed poor handling characteristics accompanied by foam generation and retention in the admixture.

Evaluation of Colourants

[0074] The colourants of Example 3, Example 4, Example 5 and Example 6 were evaluated for use in colouring concrete or mortar prepared using cement from three different sources (Golden Bay, Holcim and Dricon). The colourants were evaluated against their corresponding unformulated pigments (milled iron oxides) with (Example 4, Example 5 and Example 6) or without (Example 3) the addition of fumed silica. The colourants were evaluated for any adverse effects on the setting and hardening characteristics of the resulting cementitious building material calorimetry was used to evaluate early age hydration of the cementitious building material. Compressive strengths of 50 mm cubes of cement mortar was determined at 48 hours, 7 days and 28 days.

Calorimetry

[0075] Heat output curves for coloured mortars prepared using the different sources of cement are presented in FIG. 3 (Golden Bay), FIG. 4 (Holcim) and FIG. 5 (Dricon). The absence of any significant variation between the heat flows measured confirms the compatibility between the colourants with the cementitious building material. By contrast, the effect on heat flows of the addition of a commonly used plasticizer (2% by weight of DC31) is shown in FIG. 1.

Compressive Strength

[0076] Colourants were added at a rate of 3% by weight to a slurry of cement (0.4 (w/w) water-cement) and the compressive strength of hardened blocks (505050 mm) determined. Slurries were prepared using cement sourced from either Golden Bay or Holcim. The compressive strength determined for coloured hardened blocks prepared using these two sources of cement are presented in Table 2 (Golden Bay) and Table 3 (Dricon). Compressive strengths were also determined for coloured hardened blocks prepared by the addition of colourant at a rate of 3% by weight to a slurry of cement and sand (0.4 (w/w) water-cement and 1.5 (w/w) sand-cement). The compressive strengths determined for the coloured hardened blocks are presented in Table 4 (Golden Bay) and Table 5 (Dricon). The moderate reduction in strength (circa 10%) may be readily compensated for by addition of cement to the premix.

TABLE-US-00012 TABLE 2 Compressive strengths at 48 hours, 7 days and 28 days following hydration of coloured (3% (w/w) colourant) and uncoloured (control) hardened blocks prepared using cement (0.4 (w/w) water-cement) sourced from Golden Bay. Colourant 48 hours 7 days 28 days Control 39.7 56.5 73.0 Example 3 40.3 57.6 75.5 Example 4 38.9 59.4 73.6 Example 5 39.3 60.5 80.3 Example 6 38.0 57.7 74.4

TABLE-US-00013 TABLE 3 Compressive strengths at 48 hours, 7 days and 28 days following hydration of coloured (3% (w/w) colourant) and uncoloured (control) hardened blocks prepared using cement (0.4 (w/w) water-cement) sourced from Dricon. Colourant 48 hours 7 days 28 days Control 43.4 59.1 78.8 Example 3 41.0 54.4 70.6 Example 4 39.8 53.4 67.3 Example 5 42.6 57.2 72.5 Example 6 38.2 50.1 65.2

TABLE-US-00014 TABLE 4 Compressive strengths at 7 days and 28 days following hydration of coloured (3% (w/w) colourant) and uncoloured (control) hardened blocks prepared using a 1.5 (w/w) mixture of sand and cement (0.4 (w/w) water-mixture). The cement was sourced from Golden Bay. Sample 7 days 28 days Control 52.1 61.9 Example 3 47.8 57.6 Example 4 42.4 54.9 Example 5 46.9 57.5 Example 6 46.7 59.0

TABLE-US-00015 TABLE 5 Compressive strengths at 7 days and 28 days following hydration of coloured (3% (w/w) colourant) and uncoloured (control) hardened blocks prepared using a 1.5 (w/w) mixture of sand and cement (0.4 (w/w) water-mixture). The cement was sourced from Dricon. Sample 7 days 28 days Control 46.4 57.9 Example 3 46.3 62.5 Example 4 36.9 61.2 Example 5 49.5 62.2 Example 6 47.6 59.0

Colouring of Self-Levelling Cementitious Floor Coverings

[0077] The surface of a contained area of floor substrate was cleaned and prepared according to the supplier's instructions prior to pouring of the cementitious floor levelling product SIKA LEVEL 30 (Sika (NZ) Limited). The colourant was added to the water used in mixing of the product at a ratio of 2% (w/w) of the product. The coloured concrete was then applied to the cleaned and prepared surface of the floor substrate. By contrast with commercially available formulations of iron oxide the addition of the colourant had no significant effect on air entrainment, workability, or curing and setting times. Photographs of samples of coloured and uncoloured white cement are provided in FIG. 6. Although provided in greyscale the photographs show the uniform distribution of the pigment throughout the hardened concrete.

[0078] Although the invention has been described with reference to embodiments or examples it should be appreciated that variations and modifications may be made to these embodiments or examples without departing from the scope of the invention. Where known equivalents exist to specific elements, features or integers, such equivalents are incorporated as if specifically referred to in this specification. In particular, variations and modifications to the embodiments or examples that include elements, features or integers disclosed in and selected from the referenced publications are within the scope of the invention unless specifically disclaimed. The advantages provided by the invention and discussed in the description may be provided in the alternative or in combination in these different embodiments of the invention.

REFERENCED PUBLICATIONS

[0079] Anon (2010) Standard Specification for Pigments for Integrally Coloured Concrete (C959/C959M) ASTM International, 100 Bar Harbour Drive, PO Box C 700, West Conshohocken, Pa. 19428-2959, U.S.

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[0082] Hertz et al (2012) Concrete Colouring Compositions and Methods U.S. patent application Ser. No. 13/345,200 (publ. no. US 2012/0247372 A1).

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[0085] Kohler et al (1998) Preparation and Use of Iron Oxide Black Pigment Granules U.S. Pat. No. 5,718,755.

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[0089] Supplee (2003) Concrete Admixture with Improved Durability and Efflorescence Control Containing a Highly Resilient Colourant U.S. Pat. No. 6,537,366.

[0090] Supplee (2007) Integral or Shake-on Colourant Admixture with Improved Colour Durability in Concrete and Other Cementitious Systems Using Highly Resilient Colourants Organic or Oxide in Nature U.S. patent application Ser. No. 11/760,421 (publ. no. US 2007/0294843 A1).

[0091] Tomkinson (1971) Iron Oxide Pigments U.S. Pat. No. 3,619,227.

[0092] Will (1998) Process for Colouring Concrete Using Compacted Inorganic Granules U.S. Pat. No. 5,853,476.