Geopolymer coating and mortar

Abstract

Use of a geopolymer in a coating composition for a building construction component, a coated component for use in building construction wherein the coating comprises a geopolymer, a method of coating a component comprising applying a curable geopolymer mixture to a surface of the component and curing the mixture to form a cured geopolymer coating, and the use of a geopolymer as a mortar.

Claims

1. A method of binding adjacent building components together comprising the steps: a) applying a curable geopolymer foam mixture to a surface of a first construction component, wherein the curable geopolymer foam mixture comprises: about 10% to about 35% by weight of a metakaolin; up to about 30% by weight of a muscovite mica; about 10% to about 50% by weight of an aqueous alkali metal silicate solution, the solution comprising 20 to 50% by weight of alkali metal silicate; about 5% to about 25% by weight of an alkali metal hydroxide; and optionally up to 40% by weight of additional fillers; b) placing a second construction component adjacent to the first construction component, wherein the applied curable geopolymer foam mixture is between the first and second construction components; and c) curing the curable geopolymer foam mixture to form a cured foamed geopolymer which binds the first and second construction components together.

2. The method according to claim 1, wherein the curable geopolymer foam mixture is prepared from a curable mixture comprising: about 17.8% by weight of a metakaolin; about 21.5% by weight of a muscovite mica; about 29.8% by weight of an aqueous alkali metal silicate solution (with about 34% by weight of alkali metal silicate); about 16.7% by weight of an alkali metal hydroxide; and optionally about 0.06% by weight of a blowing agent.

3. The method according to claim 1, wherein the cured foamed geopolymer has a density of 0.1 to 1.8 g/cm3.

4. The method according to claim 1, comprising a blowing agent in the mixture at 0.01-2% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1a is a graph indicating the temperature-related weakening of steel as a function of temperature in degrees Celsius versus Strength Retention Factor.

(3) FIG. 1b is a graph indicating the yield strength and tensile strength of plain carbon steel (SA-192) as a function of temperature.

(4) FIG. 2 is a cross-sectional representation of a geopolymer foam-coated building element in accordance with the present invention.

(5) FIG. 3 is a diagrammatic representation of a wall using a geopolymer mortar defined in accordance to the present invention.

(6) A specific embodiment in accordance with the present invention is now described with reference to the diagrams of FIG. 2.

(7) With reference to the diagram of FIG. 2, there is shown a cross-section of a geopolymer foam-coated I section structural steel member 1 suitable for use as a support member (such as a support beam) in a building. Coated member 1 has an uncoated steel member 2 with a geopolymer foam coating 3 thereon.

(8) Coating 3 may be applied to uncoated steel member 2 (e.g., by spraying a curable geopolymer foam composition) either in situ at a building construction site by a site worker. Otherwise, coated member 1 may be pre-fabricated off-site and subsequently brought to and positioned at the building construction site as required. Coating 3 forms a fixed fire-proofing and heat-resistant layer for steel member 2 which increases the heat-up time for steel member 2 during a fire. This prolongs the period where the structure of steel member 2 remains intact and thus when a building supported by steel member 2 may remain stable (see earlier discussion in relation to the graph of FIGS. 1a and 1b).

(9) Prior to application to steel member 2, the curable geopolymer foam composition is prepared as follows. Percentage by weight amounts are applicable to the whole of the curable composition.

(10) 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.

(11) Alternatively, in a suitable container, to a bulk dry mixture consisting of about 22% by weight of metakaolin (Argical-M 1200S, AGS Minraux) flash calcined at approximately 750 C.; about 21% by weight of a muscovite mica (Imerys M814, Imerys) and about 1.3% of cellulosic fibres added a liquid aqueous mixture consisting of 35.2% by weight of a 34% by weight aqueous potassium silicate solution (Crosfield K66) with 8.5% by weight of potassium hydroxide dissolved therein. Finally about 2% by weight of hydrogen peroxide (100 Vol) is added just prior to application.

(12) The mixture is stirred rapidly by manual stirring means to evenly distribute the dry mixture constituents with the aqueous liquid constituents. As the onset of geopolymer curing and foaming is immediate, the mixture increases in viscosity to a level suitable for application by spraying on to the surface of uncoated steel member 2.

(13) A further specific embodiment in accordance with the present invention is now described with reference to FIG. 3.

(14) At FIG. 3, there is a wall 4 made up of clay bricks 5 stacked vertically on top of one another. Wall cross-section 6 shows interfaces 7 between clay bricks 5. At panel 8, there is shown a magnified portion of wall cross-section 6 wherein geopolymer foam 9 prepared as outlined above for FIG. 2 has been applied between upper surface 10 and lower surface 11 of clay bricks 5, whereupon curing of geopolymer foam 9, a strong bond between bricks 5 is established.

(15) The use of the geopolymer foam as a mortar allows the much closer fitting of blocks (such as bricks) than using a conventional mortar (e.g., OPC). When constructing a structure such as wall 4, the mortar is applied to a lower brick and then the next brick is fitted. The mortar expands to fill surface irregularities on the block and provides a very close bonding to the block. The thickness of the applied mortar can thus be substantially less than using a conventional mortar, thus saving on the weight of mortar material taken up the building/structure and consequently cost. Moreover, the application and building time is considerably less than using OPC. The use of a dispenser for the application of the geopolymer foam mortar enables faster application of the mortar to brick/block surfaces and the more rapid setting (curing) of the geopolymer foam mortar enables a greater height of wall or other structure to be built in a shorter period of time than by using a conventional mortar.

REFERENCES

(16) 1. Nalco Company: Nalco Guide to Boiler Failure Analysis (2011), Second Edition. Short-Term Overheating, Access Engineering, McGraw-Hill Professional.