FIRE RESISTANT CALCIUM SULPHATE-BASED PRODUCTS

Abstract

The present invention provides a calcium sulphate-based product (e.g. a wall board) comprising gypsum, a pozzolan source such as a clay additive, rice husk ash or diatomaceous earth and a metal salt additive. The product may be produced by drying an aqueous slurry comprising calcined gypsum, the pozzolan source and the metal salt additive. The clay additive may be a kaolinitic clay. The metal salt additive may be a magnesium salt e.g. magnesium nitrate, magnesium chloride or magnesium hydroxide.

Claims

1-56. (canceled)

57. A calcium sulphate-based product comprising gypsum, a pozzolan source and a metal salt additive wherein the metal salt additive is provided in an amount between 5 and 25 wt % (based on the weight of the gypsum, pozzolan source and metal salt) and the metal salt is a nitrate or a chloride.

58. A calcium sulphate-based product according to claim 57 wherein the pozzolan source is a kaolinitic clay additive and is included in an amount between 5 and 30 wt % (based on the weight of the gypsum, clay additive and metal salt additive).

59. A calcium sulphate-based product according to claim 57 wherein the pozzolan source is rice husk ash or diatomaceous earth and is included in an amount equal to or greater than 20 wt %.

60. A calcium sulphate-based product according to claim 57 wherein the wt % amount of metal salt and the wt % amount of pozzolan source is equal.

61. A calcium sulphate-based product according to claim 57 comprising 50-85 wt % gypsum.

62. A calcium sulphate-based product formed from drying an aqueous slurry containing calcined gypsum, a pozzolan source and a metal salt additive wherein the metal salt additive is provided in the slurry in an amount between 5 and 25 wt % (based on the weight of the calcined gypsum, pozzolan source and metal salt) and the metal salt is a nitrate or a chloride.

63. A calcium sulphate-based product according to claim 62 wherein the pozzolan source is a kaolinitic clay additive and is included in the slurry in an amount between 5 and 30 wt % (based on the weight of the calcined gypsum, clay additive and metal salt additive).

64. A calcium sulphate-based product according to claim 62 wherein the pozzolan source is rice husk ash or diatomaceous earth and is included in the slurry in an amount equal to or greater than 25 wt %.

65. A calcium sulphate-based product according to claim 62 wherein the wt % amount of metal salt and the wt % amount of clay additive is equal.

66. A calcium sulphate-based product according to claim 62 wherein the calcined gypsum is included in the slurry in an amount of 50-85 wt %.

67. A calcium sulphate-based composition for forming a calcium sulphate-based product by drying an aqueous slurry of the composition, wherein the composition contains calcined gypsum, a pozzolan source and a metal salt additive wherein the metal salt additive is provided in an amount between 5 and 25 wt % (based on the weight of the calcined gypsum, pozzolan source and metal salt) and the metal salt is a nitrate or a chloride.

68. A calcium sulphate-based composition according to claim 67 wherein the pozzolan source is a kaolinitic clay additive and is included in the composition in an amount between 5 and 30 wt % (based on the weight of the calcined gypsum, clay additive and metal salt additive).

69. A calcium sulphate-based composition according to claim 67 wherein the pozzolan source is rice husk ash or diatomaceous earth and is included in an amount equal to or greater than 25 wt %.

70. A calcium sulphate-based composition according to claim 67 wherein the wt % amount of metal salt and the wt % amount of clay additive is equal.

71. A calcium sulphate-based composition according to claim 67 wherein the calcined gypsum is included in an amount of 50-85 wt %.

72. A calcium sulphate-based composition according to claim 67 wherein the metal salt additive comprises calcium, magnesium, copper, zinc or aluminium.

73. A calcium sulphate-based composition according to claim 72 wherein the metal salt is magnesium nitrate or magnesium chloride.

74. A method of forming a calcium sulphate-based product by drying an aqueous slurry comprising a calcium sulphate-based composition according to claim 67.

75. A calcium sulphate-based product according to claim 57 wherein the metal salt additive comprises calcium, magnesium, copper, zinc or aluminium.

76. A calcium sulphate-based product according to claim 57 wherein the metal salt is magnesium nitrate or magnesium chloride.

Description

EXPERIMENTAL

[0057] The following examples show products having improved strength after exposure to high temperatures and are given by way of illustration only.

Control Sample 1

[0058] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres. 750 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Control Sample 2—Kaolin (30 wt %)

[0059] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Control Sample 3—Magnesium Nitrate (10 wt %)

[0060] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of magnesium nitrate hexahydrate. 750 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Control Sample 4—Calcium Nitrate (10 wt %)

[0061] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of calcium nitrate tetrahydrate. 750 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Control Sample 5—Magnesium Hydroxide (10 wt %)

[0062] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g magnesium hydroxide. 750 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Control Sample 6—Aluminium Nitrate (10 wt %)

[0063] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g aluminium nitrate nonahydrate. 750 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 1—Magnesium Nitrate (9 wt %)/Kaolin (27 wt %)

[0064] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of magnesium nitrate hexahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 2—Magnesium Nitrate (23 wt %)/Kaolin (23 wt %)

[0065] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 225 g of magnesium nitrate hexahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 3—Magnesium Nitrate (16.5 wt %)/Kaolin (16.5 wt %)

[0066] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 150 g of magnesium nitrate hexahydrate. 150 g of kaolin and 600 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 4—Magnesium Nitrate (13 wt %)/Kaolin (13 wt %)

[0067] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 112.5 g of magnesium nitrate hexahydrate. 112.5 g of kaolin and 637.5 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 5—Magnesium Nitrate (11 wt %)/Kaolin (11 wt %)

[0068] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 93.75 g of magnesium nitrate hexahydrate. 93.75 g of kaolin and 565.25 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 6—Magnesium Nitrate (9 wt %)/Kaolin (9 wt %)

[0069] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of magnesium nitrate hexahydrate. 7 g of kaolin and 675 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 7—Magnesium Hydroxide (9 wt %)/Kaolin (27 wt %)

[0070] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of magnesium hydroxide. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 8—Magnesium Chloride (9 wt %)/Kaolin (27 wt %)

[0071] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of magnesium chloride hexahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 9—Magnesium Chloride (11 wt %)/Kaolin (11 wt %)

[0072] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 93.75 g of magnesium chloride hexahydrate. 93.75 g of kaolin and 656.25 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 10—Calcium Nitrate (9 wt %)/Kaolin (27 wt %)

[0073] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of calcium nitrate tetrahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 11—Zinc Nitrate (9 wt %)/Kaolin (27 wt %)

[0074] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of zinc nitrate hexahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 12—Copper Nitrate (7 wt %)/Kaolin (28 wt %)

[0075] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 60 g of copper nitrate tetrahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 13—Aluminium Nitrate (9 wt %)/Kaolin (27 wt %)

[0076] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 75 g of aluminium nitrate nonahydrate. 225 g of kaolin and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 14—Magnesium Nitrate (13 wt %)/Rice Husk Ash (13 wt %)

[0077] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 93.75 g of magnesium nitrate hexahydrate. 93.75 g of diatomaceous earth and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 15—Magnesium Nitrate (11 wt %)/Diatomaceous Earth (27 wt %)

[0078] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 93.75 g of magnesium nitrate hexahydrate. 225 g of diatomaceous earth and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

Example 16—Magnesium Nitrate (11 wt %)/Rice Husk Ash (27 wt %)

[0079] 600 g of water at 40° C. was mixed with 3.75 g of John Mansville glass fibres and 93.75 g of magnesium nitrate hexahydrate. 225 g of rice husk ash and 525 g of calcined gypsum was added to the water and the mixture was mechanically blended for 10 seconds to form a slurry. A small amount of the slurry was poured into a 320 mm×120 mm×12.5 mm silicone mould and glass tissue was pressed into the slurry to the base of the mould. The remaining slurry was poured into the mould and further layer of glass tissue was laid onto the top of the slurry. The sample was dried at 40° C. overnight (minimum 12 hours).

[0080] A summary of the sample formulations is shown in Table 1.

TABLE-US-00001 TABLE 1 Summary of sample formulations Amount of Amount of Amount of stucco/g pozzolan metal Sample (wt %) source/g (wt %) salt/g (wt %) Control 1   750 (100)    0    0 Control 2   525 (70)   225 (30)    0    kaolin Control 3   750 (90)    0   75 (10) Control 4   750 (90)    0   75 (10) Control 5   750 (90)    0   75 (10) Control 6   750 (90)    0   75 (10) Example 1   525 (64)   225 (27)   75 (9) Mg nitrate    kaolin Example 2   525 (54)   225 (23)   225 (23) Mg nitrate    kaolin Example 3   600 (67)   150 (16.5)   150 (16.5) Mg nitrate kaolin Example 4  637.5 (74) 112.5 (13) 112.5 (13) Mg nitrate kaolin Example 5 656.25 (78) 93.75 (11) 93.75 (11) Mg nitrate kaolin Example 6   675 (82)   75 (9)   75 (9) Mg nitrate    kaolin    Example 7   525 (64)   225 (27)   75 (9) Mg hydroxide    kaolin    Example 8   525 (64)   225 (27)   75 (9) Mg chloride kaolin Example 9 656.25 (78) 93.75 (11) 93.75 (11) Mg chloride kaolin Example 10   525 (64)   225 (27)   75 (9) Ca nitrate    kaolin    Example 11   525 (64)   225 (27)   75 (9) Zn nitrate    kaolin    Example 12   525 (65)   225 (28)   60 (7) Cu nitrate    kaolin    Example 13   525 (64)   225 (27)   75 (9) Al nitrate    kaolin Example 14   525 (74) 93.75 (13) 93.75 (13) Mg nitrate    rice husk ash Example 15   525 (62)   225 (27) 93.75 (11) Mg nitrate    diatomaceous earth Example 16   525 (62)   225 (27) 93.75 (11) Mg nitrate rice husk ash

Collapse Test—Horizontal Fire Test

[0081] Samples (250 mm×50 mm) were placed in a furnace at room temperature with their ends supported such that the samples rested horizontally (span between support 210 mm). The samples were heated to 1000° C. over 1.5 hours and then allowed to cool to room temperature. The samples were assessed for collapse after cooling. The distance from the bottom of the sample to the base support was measured in mm. This value was subtracted from 50 mm to give a collapse measurement. The maximum possible collapse measurement (i.e. total collapse) is 50 mm and the minimum possible collapse measurement (i.e. no collapse) is 0 mm. The collapse measurements are shown in Table 2.

TABLE-US-00002 TABLE 2 Results of collapse test Amount of Amount of pozzolan metal salt source in in slurry slurry (in (in dried dried sample)/ sample)/ Collapse/ Sample wt % wt % mm Control 1   0   0 50 Control 2   30 (26.5)   0 22 Control 3   0   10 (8.5) 50 Control 4   0   10 (8.5) 50 Control 5   0   10 (8.5) 50 Control 6   0   10 (8.5) 40 Example 1-Mg nitrate   27 (24)   9 (8) 9 Example 2-Mg nitrate   23 (21)   23 (21) 4.2 Example 3-Mg nitrate 16.5 (15) 16.5 (15) 4.5 Example 4-Mg nitrate   13 (11)   13 (11) 3.5 Example 5-Mg nitrate   11 (10)   11 (10) 5.5 Example 6-Mg nitrate   9 (8)    9 (8) 8 Example 7-Mg hydroxide   27 (24)    9 (8) 14 Example 8-Mg chloride   27 (24)    9 (8) 7 Example 9-Mg chloride   11 (10)   11 (10) 5 Example 10-Ca nitrate   27 (24)    9 (8) 12 Example 11-Zn nitrate   27 (24)    9 (8) 12.5 Example 12-Cu nitrate   28 (25)    7 (6) 14 Example 13-Al nitrate   27 (24)    9 (8) 15 Example 14-Mg nitrate/   13 (11.5)   13 (11.5) 28 rice husk ash    Example 15-Mg nitrate/   27 (24)   11 (10) 15 diatomaceous earth    Example 16-Mg nitrate/   27 (24)   11 (10) 19 rice husk ash

[0082] It can be seen that the addition of a combination of pozzolan source and a metal salt significantly improves the structural integrity of the sample. Control Example 2 shows that whilst kaolin alone provides some effect, the combination of kaolin with a metal salt provides a much greater effect.

[0083] The effect is greatest if: [0084] the wt % amounts of kaolin and metal salt in the slurry and in the product are equal and between 10 and 25 wt %; [0085] the amount of kaolin in the slurry and in the product is less than 25 wt %; [0086] the amount of rice husk ash or diatomaceous earth in the slurry is equal to or greater than 25 w %; [0087] the metal salt is magnesium nitrate or magnesium chloride.