Fire resistant geopolymer foam

Abstract

Use of a foamed geopolymer as a fire-resistant sealant material, a method of sealing an aperture or cavity for housing services in a building comprising (i) applying a curable foamed geopolymer composition to the aperture or cavity; and (ii) curing the foamed geopolymer composition, thereby creating a seal in the aperture or cavity; and wherein the cured foamed geopolymer has fire-resistant properties, and a kit of parts for preparing a foamed geopolymer for use as a fire-resistant sealant material, comprising (i) a container holding a dry mixture of components suitable for preparing a foamed geopolymer including a blowing agent and (ii) a container holding an aqueous alkaline liquid mixture of components suitable for preparing a geopolymer.

Claims

1. A kit of parts for preparing a foamed geopolymer for use as a fire-resistant sealant material, comprising: (i) a container holding a dry mixture of components suitable for preparing a foamed geopolymer including a blowing agent; and (ii) a container holding an aqueous alkaline liquid mixture of components suitable for preparing a geopolymer, wherein: (a) container (i) contains a dry mixture comprising: 20-30% by weight of a metakaolin; 20-30% by weight of a muscovite mica; and 0.1-5% by weight of a blowing agent; and (b) container (ii) contains an aqueous liquid mixture comprising an alkali metal silicate and an alkali metal hydroxide present in a ratio of 1:2 to 25:1 by weight relative to each other, wherein the aqueous liquid mixture is present in container (ii) in an amount 5 to a total of 100% by weight with reference to the dry mixture contents of container (i).

2. The kit according to claim 1, wherein the alkali metal silicate and the alkali metal hydroxide are present in the aqueous liquid mixture of container (ii) in a weight ratio between about 1:2 to 2.1.

3. The kit of parts according to claim 1, wherein the container holding the dry mixture of components comprises a gas-permeable, liquid impermeable material.

4. The kit of parts according to claim 3, wherein the gas-permeable, liquid impermeable material comprises a perforated plastics material.

5. The kit of parts according to claim 4, wherein the perforated plastics material is a polytetrafluoroethylene (PTFE) material or a polyethylene material.

6. The kit of parts according to claim 1, wherein the container holding the aqueous alkaline liquid mixture of components comprises a rupturable rubber material or a rupturable plastics material.

7. The kit of parts according to claim 6, wherein the container is a rubber balloon or pouch.

8. The kit of parts according to claim 1, wherein the container holding the aqueous alkaline liquid mixture of components comprises glass.

9. The kit according to claim 1, wherein the alkali metal silicate and the alkali metal hydroxide are present in the aqueous liquid mixture of container (ii) in a weight ratio of about 1:1.

10. The kit of parts according to claim 1, wherein the container holding the aqueous alkaline liquid mixture of components is situated within the container holding the dry mixture of components.

Description

(1) The present invention is now described with reference to the Figures of the accompanying drawing as follows:

(2) FIGS. 1a to 1d are diagrams representing the step-wise implementation of an embodiment in accordance with the use of the invention.

(3) FIG. 2 is a photograph of a section of a test wall comprising a foamed geopolymeric block used in accordance with the invention (centre) surrounded by building blocks the upper right of which is made of the prior art Nullifire B220 fire stop compound after high-temperature heat exposure.

(4) FIG. 3a is a schematic representation of a kit in accordance with the invention;

(5) FIG. 3b is a side-on representation of a vertical wall cavity to be filled;

(6) FIG. 3c is a schematic representation of the kit in use; and

(7) FIGS. 3d and 3e are diagrammatic representations of the kit positioned in the wall cavity.

(8) A specific embodiment in accordance with the present invention is now described with reference to the diagrams of FIGS. 1a to 1d.

(9) With reference to the diagram of FIG. 1a, there is shown a side-on profile of a junction 1 between a wall 2 and floor 3 in a building (not shown). Floor 3 has a vertical opening 4 through which electrical cables 5 are positioned in a pre-determined manner. The lower portion of opening 4 has a shuttering plate 6 fixed on a bottom surface 7 of floor 3 to form an open cavity 8. Electrical cables 5 pass through a hole 9 in shuttering plate 6.

(10) With reference to FIG. 1b, air spaces 10 are present between electrical cables 5. A liquid curable foamed geopolymer composition 11 is deposited into cavity 8. The liquid composition 11 is supported on shuttering plate 6 while curing takes place and has sufficient viscosity such that it does not flow through any gaps between the perimeter of hole 9 of shuttering plate 6 and electrical cables 5.

(11) With reference to FIG. 1c, as a result of the foaming process, liquid composition 11 has expanded within cavity 8 to result in a near-cured solid foamed geopolymeric mass 12, whose upper surface 13 extends vertically above the level defined by top surface 14 of floor 3. Additionally, foamed geopolymeric mass 12 has permeated air spaces 10 as shown by arrow 15.

(12) With reference to FIG. 1d, in order to align upper surface 13 with the level defined by top surface 14 to render an even surface, just prior to complete curing and whilst still capable of manipulation, foamed geopolymeric mass 12 is leveled by manual scraping (not shown) to remove excess geopolymer and to result in even surface 16 of foamed geopolymeric mass 12, substantially co-planar with top surface 14. After complete curing, cavity 8 has been filled (sealed) with a cured (solidified) foamed geopolymeric mass 17 which is a lightweight, fire-resistant material whereby electrical cables 5 are now fixed in position and a seal is created filling in opening 4 of floor 3.

(13) Prior to deposition in cavity 8, liquid curable foamed geopolymer composition 11 is prepared as follows. Percentage by weight amounts are applicable to the whole of the curable composition.

(14) In a suitable container (5 L), to a bulk dry mixture consisting of 25% by weight of metakaolin (Argical-M 1200S, AGS Minraux) calcined at approximately 750 C.; 24% by weight of a muscovite mica (Imerys M814, Imerys) and 0.35% by weight of aluminium powder (200 mesh (75 micron), Sigma-Aldrich) is added a liquid aqueous mixture consisting of 42.5% by weight of a 29% by weight aqueous potassium silicate solution (Crosfield K66) with 8.15% by weight of potassium hydroxide dissolved therein. The mixture is stirred rapidly by manual stirring means to evenly distribute the dry mixture components with the aqueous liquid components.

(15) As the onset of geopolymer curing and foaming is immediate, the mixture increases in viscosity to a level suitable for deposition in cavity 8.

(16) With reference to FIG. 2, a solid block of a foamed geopolymer used in accordance with the invention was prepared from the liquid curable foamed geopolymer composition 11 described above. The block (dark) of foamed geopolymer was incorporated into a test wall surrounded by similar dimension blocks (light) made from Nullifire B220 fire stop compound. The wall is of average thickness of 10 cm.

(17) The wall was subjected to heat test conditions simulating a building fire in accordance with a standard procedure, wherein the temperature of an inside heat-facing surface of the wall was gradually raised to greater than 1000 C. over about a 30-minute period and was maintained at that temperature for 1.5 hours. For the duration of the heating, the outside surface of the wall temperature stays below 100 C. as determined by a thermocouple arrangement for the 2-hour duration of the test.

(18) As can be seen from FIG. 2, the light blocks made of the prior art material have undergone significant and undesirable cracking as a result of the heat treatment compared to the dark block made of the foamed geopolymer. This demonstrates the superior fire resistant properties of the foamed geopolymer used in accordance with the present invention in comparison to the prior art material, thus demonstrating further the foamed geopolymer's effective usage as a fire-resistant sealant material.

(19) A further specific embodiment in accordance with the present invention is described with reference to the diagrams of FIGS. 3a to 3c.

(20) With reference to FIG. 3a, there is shown a kit according to the invention which is a pillow 1 which has a sealed bag 2 containing dry mixture 3 and capsule 4 containing liquid mixture 5.

(21) Sealed bag 2 is composed of a flexible gas-permeable, liquid non-permeable material such as a perforated polytetrafluoroethylene or polyethylene sheet. Dry mixture 3 is a powdered blend consisting of metakaolin, a muscovite mica and aluminium powder as a blowing agent. Capsule 4 is a rubber balloon filled with liquid mixture 5, which is an aqueous liquid solution consisting of alkali metal silicate and an alkali metal hydroxide as solutes.

(22) With reference to FIG. 3b, there is shown a side-on, cut away view of cavity 6 in a wall 7. Passing through cavity 6 is electrical cable 8.

(23) With reference to FIG. 3c, there is pillow 1 which has been manually manipulated through squeezing such that capsule 4 is broken to permit liquid mixture 5 to contact dry mixture 3 by flowing through ruptures 9 in the direction of arrows 10. Sealed bag is further manipulated to enable thorough mixing of liquid mixture 5 and dry mixture 3, which commences a reaction leading to a cured geopolymeric foam. Ruptured capsule 11 results from capsule 4.

(24) With reference to FIG. 3d, pillow 1 has ruptured capsule 11 surrounded by curing geopolymer 12. Pillow 1 is inserted into cavity 6 in order to seal cavity 6 and fix in place electrical cable 11 as curing geopolymer 12 cures and expands. Once mixed, the alkaline liquid mixture 5 reacts with the aluminium powder of dry mixture 3 to produce hydrogen gas (not shown) as the foaming gas, which expands curing geopolymer 12. A secondary effect of this reaction is the generation of heat which assists in the curing of geopolymer 12 over a period of time.

(25) As can be seen from FIG. 3e, after a suitable time period, pillow 1 contains cured geopolymer foam 13 and upon its expansion has substantially filled cavity 6 and secured electrical cable 11 in place wedged between sealed bag 2 and wall 7.

(26) In the event of a fire (not shown), the sealed bag 2 swiftly burns away leaving the cured geopolymer foam 12 remaining intact sealing cavity 6 and retaining the tight fixing grip on electrical cable 8.