GEOPOLYMER FOAMS BASED ON CERAMIC MATERIALS

Abstract

As geopolymer foam formulation including an inorganic binder, a ceramic material, an alkaline activator, an alkyl polyglucoside, a gas phase and water. Moreover, a process for the manufacture of such formulation by means of mechanical and/or chemical foaming as well as to a process for the manufacture of a hardened geopolymer foam therefrom. Also, a geopolymer foam element including the hardened geopolymer foam. Finally, the use of ceramic materials for substituting fly ashes in geopolymer foam formulations. The ceramic material is preferably brick dust.

Claims

1. A geopolymer foam formulation comprising: a pozzolanic binder selected from metakaolin, microsilica and mixtures thereof; at least one pulverulent burnt clay material; at least one alkaline activator selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal aluminates, alkali metal silicates and mixtures thereof; at least one surfactant of the alkyl polyglucoside type; a gas phase and water.

2. The geopolymer foam formulation according to claim 1, wherein the pulverulent burnt clay material comprises from 30 to 75% by weight of SiO.sub.2 and from 5 to 35% of Al.sub.2O.sub.3.

3. The formulation according to claim 1, wherein the pozzolanic binder is a mixture of metakaolin and microsilica.

4. The formulation according to claim 1, wherein the pulverulent burnt clay material is brick dust.

5. The formulation according to claim 1, wherein the pulverulent burnt clay material has a d.sub.90-value below 1350 ?m and a d.sub.50-value below 600 ?m, as measured by laser granulometry.

6. The formulation according to claim 1, wherein the alkaline activator is selected from alkali metal hydroxides of the formula MOH and alkali metal silicates of the formula m SiO.sub.2.Math.n M.sub.2O, wherein M stands for Li, Na, or K, or a mixture thereof, and the molar ratio m:n is ?4.0.

7. The formulation according to claim 1, wherein the alkaline activator comprises a mixture of alkali metal hydroxides and of alkali metal silicates.

8. The formulation according to claim 1, wherein the alkyl polyglucoside has the formula H(C.sub.6H.sub.10O.sub.5).sub.mOR, where (C.sub.6H.sub.10O.sub.5) is a glucose unit, R is a C.sub.6-18-alkyl group, and m is from 1 to 5.

9. The formulation according to claim 1, wherein the gas phase is selected from the group consisting of air, oxygen, hydrogen, nitrogen, a noble gas, hydrocarbons and mixtures thereof.

10. The formulation according to claim 1, wherein from 20 to 95% by volume of the formulation consists of the gas phase.

11. The formulation according to claim 1, wherein the formulation comprises from 10 to 60% by weight of water.

12. The formulation according to claim 1, wherein the formulation comprises up to 20% by weight of a cement.

13. The formulation according to claim 1, wherein all of the constituents are present together as a single component, or all solid constituents of the formulation are held in a first, solid component and the water is held in a second, liquid component, or the pozzolanic binder and the pulverulent burnt clay material are held in a first, solid component and the at least one alkaline activator and the water are held in a second, liquid component.

14. The formulation according to claim 1, wherein the formulation also comprises at least one additive for foam stabilization, shrinkage reduction, flexibilization, hydrophobization, or dispersion; as well as fibers, fillers, or mixtures thereof.

15. The formulation according to claim 1, wherein the formulation comprises: from 5 to 50% by weight of metakaolin and/or microsilica, from 5 to 50% by weight of the pulverulent burnt clay material, from 1 to 55% by weight of alkaline activator (calculated as solids), from 10 to 50% by weight of water (total quantity), from 0.01 to 5% by weight of surfactant and a gas phase.

16. A process for the manufacture of the formulation according claim 1, comprising the steps of: mixing all solid and liquid components of the formulation and introducing the gas phase by means of mechanical and/or chemical foaming.

17. A process according to claim 16, additionally comprising the step of: allowing the formulation to harden and optionally to dry.

18. A geopolymer foam element comprising the hardened geopolymer foam according to claim 17.

19. The geopolymer foam formulation according to claim 1, wherein there are no fly ashes in the geopolymer foam formulation.

Description

[0081] The examples and the attached figures below will now provide further, non-limiting explanation of the present invention. In the drawings:

[0082] FIG. 1 shows a comparison of compressive strengths of different geopolymer foam samples,

[0083] FIG. 2 shows a hardened geopolymer foam containing metakaolin and fly ash,

[0084] FIG. 3 shows a hardened geopolymer foam containing metakaolin, fly ash and microsilica,

[0085] FIG. 4 shows a hardened geopolymer foam containing metakaolin and slag,

[0086] FIG. 5 shows a hardened geopolymer foam containing metakaolin, slag and microsilica,

[0087] FIG. 6 shows a hardened geopolymer foam containing metakaolin and milled brick waste, and

[0088] FIG. 7 shows a hardened geopolymer foam containing metakaolin, milled brick waste and microsilica.

EXAMPLES

Characterization of the Starting Materials:

[0089] An eluate analysis of constituents of geopolymer foam formulations, performed according to DIN EN ISO 11885 (E 22): 2009-09, can be found in Table 2 hereinbelow. Fly ash, for instance, contains high amounts Barium, Chromium, Molybdenum and Selenium. Microsilica, on the other hand, contains high amounts of Arsenic. Upon use, the contamination with heavy metals is transferred to the resulting geopolymers leading to a disposal problem of the geopolymer material.

TABLE-US-00002 TABLE 2 Microsilica Ceramic Fly ash Slag (RW-Fuller brick waste (Microsit 10, (Karlstatt Q1+, RW (Ziegelmehl, BauMineral 4000, silicium PILOSITH GmbH, Schwenk GmbH, GmbH, Eluate Herten, Zement KG, Pocking, Parensen, Analysis DE) Ulm, DE) DE) DE) As [mg/L] 0.04 0.001 0.29 0.07 Ba [mg/L] 0.49 0.05 <0.01 0.04 Cl [mg/L] 10.92 13.12 12.22 10.40 Cr [mg/L] 0.39 0.02 0.01 0.01 Cu [mg/L] <0.001 <0.001 0.01 0.01 Mo [mg/L] 1.21 0.01 0.02 0.03 S [mg/L] 292.8 22.8 9.98 26.6 Sb [mg/L] 0.03 <0.0001 <0.0001 <0.0001 Se [mg/L] 0.14 0.004 <0.001 <0.001

[0090] Ceramic brick waste thus comprises low amounts of elutable pollutants. Milling of the brick waste is advantageous in order to obtain high-strength low-density foams, as shown in FIG. 1 hereinbelow.

[0091] The chemical composition of the above-mentioned milled ceramic brick waste (Ziegelmehl) was already reported in Table 1 above. The chemical compositions of other silica-based starting materials (the same types as mentioned above) were measured via XRF (see Table 3 hereinbelow):

TABLE-US-00003 TABLE 3 Solid state chemistry (XRF, fused bead) Fly ash Slag Microsilica Sulfate SO.sub.3 [wt.-%] 0.55 0.86 0.02 Calcium CaO [wt.-%] 4.64 41.82 0.06 Potassium K.sub.2O [wt.-%] 2.30 0.54 0.05 Sodium Na.sub.2O [wt.-%] 1.10 0.22 <0.01 Silicon SiO.sub.2 [wt.-%] 51.87 36.28 95.21 Iron Fe.sub.2O.sub.3 [wt.-%] 6.44 0.54 0.20 Aluminum Al.sub.2O.sub.3 [wt.-%] 23.57 11.45 0.15 Magnesium MgO [wt.-%] 2.18 6.79 <0.01

[0092] Beside the chemical composition of the constituents, their particle size is very important. A low particle size and advantageous grain size distribution are beneficial to achieve robust foams at low densities (<200 g/L). Lowering the density of a foamed material also induces a lowering of the thickness of the cellular walls. This requires the aggregate size of the fillers being significantly smaller than the average cell wall thickness of the resulting inorganic foam. The particle size distributions are reported in Table 4 hereinbelow. Particle sizes were determined by laser granulometry (MasterSizer 2000, Malvern Panalytical, UK).

TABLE-US-00004 TABLE 4 Slag Microsilica Fly ash Fly ash (Karlstatt (RW-Fuller (Microsit 10, (Microsit 90, 4000, Q1+, RW BauMineral BauMineral Schwenk silicium GmbH, GmbH, Zement GmbH, Particle-size Herten, Herten, KG Ulm, Pocking, Distribution DE) DE) DE) DE) d.sub.10 [?m] 0.8 2.1 1.5 1.1 d.sub.50 [?m] 3.9 14.2 10.1 2.5 d.sub.63 [?m] 5.1 22.2 14.8 3.4 d.sub.90 [?m] 10.2 63.8 35.6 12.7

[0093] For brick waste Ziegelmehl 0-1.25 mm (obtained from PILOSITH GmbH, Parensen, Germany), particle size distribution was determined. Milling was performed at 70 rpm for 50 minutes (sample 1), 35 minutes (sample 2), 25 minutes (sample 3) or 15 minutes (sample 4) in a Retsch BT100XL ball mill (RETSCH GmbH, Haan, Germany). Particle size distribution of the brick waste as received and the milled brick waste samples is presented in Table 5. (This particle size distribution is very similar to Microsit 90 fly ashsee Table 4 above). The particle size measurement was performed by means of laser granulometry (MasterSizer 2000, Malvern Panalytical, UK).

TABLE-US-00005 TABLE 5 Brick Milled Milled Milled Milled waste brick brick brick brick Particle-size as waste waste waste waste distribution received sample1 sample 2 sample 3 sample 4 d.sub.10 [?m] 48 2.3 9.2 15.7 28.3 d.sub.50 [?m] 574 16.6 111.7 225.2 406.5 d.sub.63 [?m] 763 25.5 172.3 335.8 571.7 d.sub.90 [?m] 1306 60.9 351.4 650.7 1087.8

Example 1

[0094] To illustrate the influence of particle sizes on compressive strength of hardened geopolymer foams, samples were prepared from the following composition of raw materials in percent by weight. [0095] 31.6% Potassium Waterglass (Kaliumwasserglas 58, BASF SE, Ludwigshafen, Germany 56% in H.sub.2O, module=1.7) [0096] 3.2% Sodium Waterglass (Metso 520, PQ Corp., Amersfoort, Netherlands, module=1.0) 19.4% Water [0097] 0.7% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE, Ludwigshafen, Germany) [0098] 22.0% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, France, d.sub.50=1-2 ?m) [0099] 2.7% Acrylic Dispersion (Acronal S430P, BASF SE, Ludwigshafen, Germany) [0100] 20.4% component a, b, c, d, e or f [0101] a) Fly Ash Class F (Microsit 10) [0102] b) Coarse brick waste as received (Ziegelmehl 0-1.25 mm) [0103] c) Milled brick waste sample 1 (Ziegelmehl 0-1.25 mm) according to Table 5. [0104] d) Milled brick waste sample 2 (Ziegelmehl 0-1.25 mm) according to Table 5. [0105] e) Milled brick waste sample 3 (Ziegelmehl 0-1.25 mm) according to Table 5. [0106] f) Milled brick waste sample 4 (Ziegelmehl 0-1.25 mm) according to Table 5.

[0107] Foam samples containing component a, b, c, d, e or f, respectively, were produced by mixing the liquid raw materials. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass. The resulting geopolymer foam samples exhibited a dimension of 300 mm?300 mm?40 mm respectively. The following properties were measured for the foam samples: [0108] a) Dry density: 291 kg/m.sup.3 [0109] Compressive strength after ?28d: 0.64 MPa [0110] b) Dry density: 294 kg/m.sup.3 [0111] Compressive strength after ?28d: 0.31 MPa [0112] c) Dry density: 293 kg/m.sup.3 [0113] Compressive strength after ?28d: 0.57 MPa [0114] d) Dry density: 290 kg/m.sup.3 [0115] Compressive strength after ?28d: 0.45 MPa [0116] e) Dry density: 292 kg/m.sup.3 [0117] Compressive strength after ?28d: 0.38 MPa [0118] f) Dry density: 295 kg/m.sup.3 [0119] Compressive strength after ?28d: 0.34 MPa

[0120] The results are illustrated in FIG. 1 (dry density vs. compressive strength). The results using brick waste as received were satisfactory considering that no fly ash was used. But the finer the brick waste was milled, the higher the compressive strength values were at a dry density comparable to the fly ash sample.

Example 2 (Comparative)

[0121] A geopolymer foam was prepared from the following composition of raw materials in weight percent. [0122] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, [0123] 40% in H.sub.2O, module=1.0) [0124] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0125] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0126] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0127] 26.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR, d.sub.50=1-2 ?m) [0128] 14.9% Fly Ash Class F (Microsit 90, BauMineral GmbH, Herten, DE, about 5% CaO, 4.400 cm.sup.2/g)

[0129] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were then added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 190 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0130] The resulting geopolymer foam element exhibited a dimension of 300 mm?300 mm?40 mm. A few cracks were visible in the sample (FIG. 2). The following properties were measured: [0131] Dry density: 121 kg/m.sup.3 [0132] Compressive strength after ?28d: 31 kPa [0133] Thermal conductivity: 38.7 mW/m.Math.K

Example 3 (Comparative)

[0134] A geopolymer foam was prepared from the following composition of raw materials in weight percent: [0135] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, 40% in H.sub.2O, module=1.0) [0136] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0137] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0138] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0139] 21.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR, d.sub.50=1-2 ?m) [0140] 14.9% Fly Ash Class F (Microsit 90, BauMineral GmbH, Herten, DE, about 5% CaO, 4.400 cm.sup.2/g) [0141] 5.0% Microsilica (RW-F?ller Q1+, RW silicium GmbH, Pocking, DE, 330-360 kg/m.sup.3)

[0142] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 197 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0143] The resulting geopolymer foam element exhibited a dimension of 300 mm?300 mm?40 mm. Very few cracks were visible in the sample (FIG. 3). The following properties were measured: [0144] Dry density: 132 kg/m.sup.3 [0145] Compressive strength after ?28d: 91 kPa [0146] Thermal conductivity: 42.0 mW/m.Math.K

Example 4 (Comparative)

[0147] A geopolymer foam was prepared from the following composition of raw materials in weight percent: [0148] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, 40% in H.sub.2O, module=1.0) [0149] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0150] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0151] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0152] 26.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR,d.sub.50=1-2 ?m) [0153] 14.9% Slag (Karlstatt 4000, Schwenk Zement KG, Ulm, DE)

[0154] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 191 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0155] The resulting geopolymer foam element exhibited a dimension of 300 mm?300 mm?40 mm. A few cracks were visible in the sample (FIG. 4). The following properties were measured: [0156] Dry density: 137 kg/m.sup.3 [0157] Compressive strength after ?28d: 42 kPa [0158] Thermal conductivity: 38.3 mW/m.Math.K

Example 5 (Comparative)

[0159] A geopolymer foam was prepared from the following composition of raw materials in weight percent: [0160] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, 40% in H.sub.2O, module=1.0) [0161] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0162] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0163] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0164] 21.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR, d.sub.50=1-2 ?m) [0165] 14.9% Slag (Karlstatt 4000, Schwenk Zement KG, Ulm, DE) [0166] 5.0% Microsilica (RW-F?ller Q1+, RW silicium GmbH, Pocking, DE, 330-360 kg/m.sup.3)

[0167] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 197 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0168] The resulting geopolymer foam part exhibited a dimension of 300 mm?300 mm?40 mm. A few cracks were visible in the sample (FIG. 5). The following properties were measured: [0169] Dry density: 145 kg/m.sup.3 [0170] Compressive strength after ?28d: 147 kPa [0171] Thermal conductivity: 40.5 mW/m.Math.K

Example 6 (Inventive)

[0172] A geopolymer foam was prepared from the following composition of raw materials in weight percent: [0173] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, 40% in H.sub.2O, module=1.0) [0174] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0175] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0176] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0177] 26.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR, d.sub.50=1-2 ?m) [0178] 14.9% Milled brick waste sample 1 (milled Ziegelmehl 0-1.25 mm, as mentioned in Table 5 above)

[0179] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 198 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0180] The resulting geopolymer foam part exhibited a dimension of 300 mm?300 mm?40 mm. No cracks were visible in the sample (FIG. 6). The following properties were measured: [0181] Dry density: 128 kg/m.sup.3 [0182] Compressive strength after ?28d: 32 kPa [0183] Thermal conductivity: 38.3 mW/m.Math.K

Example 7 (Inventive)

[0184] A geopolymer foam was prepared from the following composition of raw materials in weight percent: [0185] 37.0% Potassium Waterglass (Kaliumsilikat K 45 M, Woellner GmbH, Ludwigshafen, DE, 40% in H.sub.2O, module=1.0) [0186] 21.2% Sodium Hydroxide solution (10% in H.sub.2O) [0187] 0.45% C.sub.10-16-Alkypolyglucoside (Glucopon GD 70, BASF SE) [0188] 0.15% C.sub.8-10-Alkypolyglucoside (Glucopon 225 DK, BASF SE) [0189] 21.3% Metakaolin (Argical M 1200S, Imerys Refractory Minerals, Cl?rac, FR, d.sub.50=1-2 ?m) [0190] 14.9% Milled brick waste sample 1 (milled Ziegelmehl 0-1.25 mm, as mentioned in Table 5 above) [0191] 5.0% Microsilica (RW-F?ller Q1+, RW silicium GmbH, Pocking, DE, 330-360 kg/m.sup.3)

[0192] The liquid raw materials were first mixed with NaOH solution. The solid raw materials were added to the liquid components and stirred until a homogeneous slurry was created. The foam was then generated with a kitchen mixer. The so obtained foam had a wet density of 191 kg/m.sup.3 and was poured into a mold. The setting reaction took place and the foam started to solidify. The geopolymer foam was stored in humid atmosphere for 3 days to allow proper setting. Thereafter, it was demolded and dried at RT until constant mass.

[0193] The resulting geopolymer foam part exhibited a dimension of 300 mm?300 mm?40 mm. No cracks were visible in the sample (FIG. 7). The following properties were measured: [0194] Dry density: 124 kg/m.sup.3 [0195] Compressive strength after ?28d: 93 kPa [0196] Thermal conductivity: 40.2 mW/m.Math.K

[0197] A summary of the results obtained in Examples 2-7 is presented in Table 6 below.

TABLE-US-00006 TABLE 6 Components Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Metakaolin 63.8% 51.7% 63.8% 51.7% 63.8% 51.7% Fly ash 36.2% 36.2% Slag 36.2% 36.2% Milled brick 36.2% 36.2% waste Microsilica 12.1% 12.1% 12.1% Comments cracks Small cracks Small No No cracks cracks cracks cracks Wet density 190 197 191 197 198 191 [g/L] Dry density 121 132 137 145 128 124 [g/L] Compressive 31 91 42 147 32 93 strength [kPa] Thermal 38.7 42.0 38.3 40.5 38.3 40.2 conductivity [mW/m .Math. K]

[0198] The apparent higher compressive strengths of the slag samples Ex. 4 and 5 seems to be mainly due to the higher densities thereof. The main disadvantages of Ex. 2, 3, 4 and 5 is to be seen in the crack formation of the respective samples.