WO2021003519A1

WO2021003519A1 - Waterproofing compositions and methods

Info

Publication number: WO2021003519A1
Application number: PCT/AU2020/050618
Authority: WO
Inventors: David Preston Gregory
Original assignee: Canasia Australia Pty Ltd
Priority date: 2019-07-09
Filing date: 2020-06-18
Publication date: 2021-01-14

Abstract

A composition for waterproofing a building substrate is disclosed. The composition comprises a cementitious mixture comprising calcium sulphoaluminate and at least one other cementitious material. The composition further comprises latex in a ratio with the cementitious mixture of at least 1.2:1. A method of forming a waterproofing membrane on a building substrate is further disclosed. In addition, methods of application of the composition to a surface are disclosed, including by spraying of the composition onto the surface.

Description

WATERPROOFING COMPOSITIONS AND METHODS

Technical Field

[0001] The present disclosure relates to compositions and methods for waterproofing building substrates.

Background

[0002] Various materials used in construction are susceptible to water penetration. In instances where the migration of water through the material is detrimental to the performance of a structure, waterproofing may be applied to one or more surfaces of the substrates forming the structure. For example, in the construction of buildings, waterproofing of walls, floors and ceilings is often desirable to prevent or reduce the ingress of water into the building.

[0003] Waterproofing applied to substrates may be positive side waterproofing where the water pressure pushes the waterproofing against the substrate, or negative side waterproofing where the water pressure pushes the waterproofing away from the substrate. In the example of building walls, positive side waterproofing is applied to the outer surface of the wall, while negative side waterproofing is applied to the inner surface of the wall.

[0004] Positive side waterproofing is typically favoured in the construction of new buildings. Positive side waterproofing prevents water from entering the substrate and the waterproofing is supported against the water pressure by the substrate. The primary disadvantage of positive side waterproofing is that the waterproofing is inaccessible for repairs and maintenance once the building construction is complete.

[0005] Negative side waterproofing, on the other hand, is accessible for repairs and maintenance during the life of the building, however must be sufficiently bonded to the substrate to withstand the water pressure pushing it away from the substrate. [0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

Summary

[0007] Disclosed herein are waterproofing compositions for building substrates formed from calcium sulfoaluminate, at least one other cementitious material, and latex in a ratio of at least 1.2:1 with the cementitious materials.

[0008] In one embodiment, the waterproofing compositions disclosed herein provide a composition with sufficient elasticity to maintain performance, even in the event of micro-cracking in the underlying building substrate.

[0009] In another embodiment, the waterproofing compositions disclosed herein provide a slurry of sufficient stability to allow for application to the building substrate by a variety of methods, and in particular by spraying.

[0010] In another embodiment the waterproofing compositions disclosed herein can be adapted to be suitable for both positive side and negative side waterproofing applications.

[0011] In yet another embodiment, the waterproofing compositions disclosed herein dry quickly after application to the building substrate, facilitating the application of multiple layers of the waterproofing composition to the building substrate.

[0012] In still another embodiment, the waterproofing compositions disclosed herein provide a non-toxic formulation, substantially free from volatile organic compounds (VOC’s), that is suitable for use in negative side waterproofing applications. [0013] According to the present disclosure, there is provided a composition for waterproofing a building substrate, comprising: a cementitious mixture comprising calcium sulfoaluminate and at least one other cementitious material; and latex, wherein the ratio of latex to cementitious mixture is at least 1.2:1.

[0014] The at least one cementitious material may be selected from the group consisting of: Portland cement, anhydrite, gypsum, fly ash, quick dry cement, or combinations thereof.

[0015] The latex may be selected from the group consisting of: styrene acrylic latex, natural rubber latex, polybutadiene latex, polychloroprene latex, polyvinyl acetate latex, nitrile latex, or combinations thereof. The latex may be selected based on its glass transition temperature. For example, in some embodiments, the latex has a glass transition temperature of less than or equal to around 0°C.

[0016] The composition may further comprise one or more additives selected from the group consisting of: sand, pigment, defoamer, coalescing agents, biocides, thickeners, stabiliser, fibers, thickeners, water, or combinations thereof.

[0017] The composition may further comprise a retarder for suppressing hydration of the cementitious mixture. The retarder may be, for example, tartaric acid.

[0018] The cementitious mixture may comprise at least 25% w/w calcium

sulfoaluminate, preferably at least 30% w/w, and more preferably around 50% w/w.

[0019] The ratio of the calcium sulfoaluminate to the at least one cementitious material may be at least 15:1, or even at least 20:1. Alternatively, the ratio of the at least one cementitious material may be at least 15:1, or even at least 20:1. [0020] According to the present disclosure, there is further provided a composition for waterproofing a building substrate, comprising: a cementitious mixture comprising calcium sulfoaluminate and at least one other cementitious material; and latex having a glass transition temperature of less than or equal to around 0°C, wherein the ratio of latex to cementitious mixture is at least 1.2:1.

[0021] The composition may further comprise tartaric acid.

[0022] In some embodiments, the ratio of sulfoaluminate to the at least one other cementitious material is at least 20:1.

[0023] According to the present disclosure, there is further provided a composition for waterproofing a building substrate, comprising:

50-75% w/w latex;

30-45% w/w calcium sulfoaluminate; and

1-5% other cementitious material.

[0024] The composition may further comprise 0.05-2% tartaric acid.

[0025] In some embodiments, the latex has a glass transition temperature of less than or equal to around 0°C.

[0026] The composition may further comprise one or more additives selected from the group consisting of: sand, pigment, defoamer, coalescing agents, biocides, thickeners, stabiliser, fibers, thickeners, water, or combinations thereof. [0027] According to the present disclosure, there is further provided a method of forming a waterproofing membrane on a building substrate, the method comprising: forming a slurry according to the composition disclosed herein; applying a layer of the slurry to a surface of the building substrate; and allowing the layer of slurry to dry, thereby forming a waterproofing membrane adhered to the surface of the building substrate.

[0028] The layer of slurry may be applied to the surface of the building substrate using any suitable method known in the art, for example by roller, brush or spraying. Preferably, the layer of slurry is applied to the surface of the building substrate using an airless spray system. In an embodiment, the airless spray system comprises a pressure pot having a bottom outlet.

[0029] The method may further comprise applying one or more additional layers of the slurry to the surface of the building substrate to achieve a desired thickness of the waterproofing membrane, allowing each layer of slurry to dry before application of the subsequent layer. In some embodiments, the thickness of the waterproofing membrane is 2mm (wet) or 1.5mm (dry). Preferably, the waterproofing membrane is formed from the application of two layers of 1mm (wet) thickness.

Definitions

[0030] With regards to the definitions provided herein, unless stated otherwise, or implicit from the context, the defined terms and phrases include the provided meanings. Unless explicitly stated otherwise, or apparent from context, the terms and phrases below do not exclude the meaning that the term or phrase has acquired by a person skilled in the relevant art. The definitions are provided to aid in describing particular embodiments, and are not intended to limit the claimed invention, because the scope of the invention is limited only by the claims. Furthermore, unless otherwise required by context, singular terms shall include pluralities and plural terms hall include the singular.

[0031] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0032] It is to be appreciated that certain features that are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any sub combination.

[0033] Throughout the present specification, various aspects and components of the invention can be presented in a range format. The range format is included for convenience and should not be interpreted as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range, unless specifically indicated. For example, description of a range such as from 1 to 5 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 5, from 3 to 5 etc., as well as individual and partial numbers within the recited range, for example, 1, 2, 3, 4, 5, 5.5 and 6, unless where integers are required or implicit from context. This applies regardless of the breadth of the disclosed range. Where specific values are required, these will be indicated in the specification. Description of Embodiments

[0034] With reference to the accompanying examples, there is provided a

composition for waterproofing a building substrate, comprising a cementitious mixture comprising calcium sulphoaluminate and at least one other cementitious material, and latex, wherein the ratio of latex to cementitious mixture is at least 1.2:1.

[0035] The at least one other cementitious material is not particularly limited and may be any naturally occurring or manufactured cementitious material. By way of example, the cementitious material may be selected from group consisting of: Portland cement, anhydrite, gypsum, fly ash, quick dry cement, and combinations thereof.

[0036] To improve potlife, a retarder may be included in the cementitious mixture.

For example, the cementitious mixture may include tartaric acid for suppressing hydration of the cementitious mixture. Alternatively or additionally, the potlife can be extended by providing a high proportion of the calcium sulphoaluminate or the at least one other cementitious material in the cementitious mixture. For example, the ratio of calcium sulphoaluminate to the at least one other cementitious material may be at least 15:1 or even 20:1, or alternatively the ratio of the at least one other cementitious material to calcium sulphoaluminate may be at least 15:1 or even 20:1.

[0037] The cementitious mixture may further comprise one or more additives. For example, in some embodiments the cementitious mixture may include sand or other inert fine particulate material to improve stability of the composition in its slurry form, as well as to provide wear resistance to the waterproofing once applied to the building substrate.

[0038] In some embodiments, pigment may be added to the cementitious mixture to provide a desired final colour of the waterproofing composition applied to the substrate. The amount of pigment required will depend on the desired shade of the chosen colour. Alternatively, the colour of the waterproofing composition may be controlled by careful selection of the base materials. In an example, an off white waterproofing composition can be achieved through a combination of white calcium sulphoaluminate, white Portland cement, and white sand.

[0039] Additional additives may be included in the composition as required, for example defoamers, coalescing agents, biocides, thickeners, retarders, stabilisers (e.g. diutan gum), fibers (e.g. basalt fibers, carbon fibers, cellulosic fibers), thickeners (e.g. ASE-60), water, and combinations thereof.

[0040] The type of latex used may be selected on the basis of one or more desired physical properties of the resulting composition. For example, the latex may be selected on the basis of one or more of the following properties: chemistry; stability in UV light; compatibility with cementitious materials; glass transition temperature;

elasticity; effect on drying time; stability at low temperature; degree of resistance to wear; and degree of efflorescence. By way of example, the latex may be selected based on its glass transition temperature. For example, in some embodiments, the latex has a glass transition temperature of less than or equal to around 0°C.

[0041] The latex may be any suitable latex, for example the latex may be selected from the group consisting of: styrene acrylic latex, natural rubber latex, polybutadiene latex, polychloroprene latex, polyvinyl acetate latex, nitrile latex, or combinations thereof.

[0042] The types and quantities of calcium sulphoaluminate, other cementitious material(s) and latex will vary based on the desired properties of the waterproofing composition, both in its initial slurry form for application to a building substrate, and dried form on the building substrate. In some embodiments, the types and quantities of calcium sulphoaluminate, other cementitious material(s) and latex mat be selected to control the stability and pot life of the formed slurry. The pot life refers to the time from mixing the cementitious mixture and latex until the composition thickens or sets to the point that it is not able to be applied to the building substrate. The desired pot life may vary depending on the manner in which the composition is to be applied to the building substrate and the quantity of composition being prepared. In an embodiment, the pot life of the composition is preferably at least 1 hour. It has been found that an increase in the quantity of calcium sulphoaluminate can assist in extending the pot life of the waterproofing composition.

[0043] In some embodiments, the types and quantities of calcium sulphoaluminate, other cementitious material(s) and latex may be selected to control water absorption of the membrane formed by the application of the waterproofing composition to the building substrate. Preferably, the formed membrane will absorb no more than 10% w/w water. It has been observed that the amount of water absorbed by the formed membrane can be reduced by reducing the amount of other cementitious material in the mixture, in particular the amount of anhydrite and/or gypsum present in the

cementitious mixture.

[0044] Another property that may be considered when selecting the types and quantities of calcium sulphoaluminate, other cementitious material(s) and latex is the drying time of the composition once applied to the building substrate. It has been observed that the quantity of calcium sulphoaluminate in the cementitious mixture can be varied to vary drying time of the composition. Furthermore, it has been observed that the calcium sulphoaluminate provides a fast strength development to the composition. Preferably, the drying time of the composition will be less than 1 hour, however that it will be appreciated that the formulation of the composition may be varied to provide a suitable balance between the pot life and the drying time.

[0045] According to the present disclosure, there is further provided a method of forming a waterproofing membrane on a building substrate. The method comprises forming a slurry comprising a cementitious mixture and latex. The cementitious mixture comprises calcium sulphoaluminate and at least one other cementitious material. The ratio of latex to cementitious mixture is at least 1.2:1.

[0046] A layer of the formed slurry is applied to a surface of the building substrate. The layer of slurry may be applied to the building substrate by any suitable method, for example by roller, brush or spraying. The applied layer is left to dry, thereby forming a waterproofing membrane adhered to the surface of the building substrate. Additional layers of slurry may be applied to the building substrate as required to achieve the desired level of waterproofing. In some embodiments, a 1.5 mm (dry) waterproofing membrane is achieved by applying two layers of the composition at 1mm (wet), allowing the first layer to dry prior to application of the second layer.

[0047] In a preferred embodiment, the quantities of calcium sulphoaluminate, other cementitious material(s) and latex are selected to provide a composition of suitable viscosity and stability to be applied to the building substrate by spraying. It will be appreciated that the composition can be applied to a surface area more quickly by spraying when compared to application by roller or brush. Additionally, application by spraying can provide an improved waterproofing membrane to building substrate bond by promoting partial penetration of the composition into the building substrate surface. This is particularly desirable for negative side applications of the waterproofing composition. Moreover, application by spraying provides waterproofing membrane of more uniform thickness which also assists with performance of the membrane.

[0048] In an embodiment, there is provided a spray system for application of waterproofing compositions disclosed herein to a surface of a building substrate. The spray system is preferably an airless spray system. It was observed that such airless spray systems provide a good penetration into the surface of the building substrate surface, uniform coating of composition over the surface of the building substrate, and allowed for relatively fast application of the composition.

[0049] For certain formulations, for example formulations having higher viscosity or comprising higher levels of particulate material such as sand, it may be preferable to use an airless spray system comprising a pressurised bottom outlet. As discussed with reference to Example 1 below, a spray speed of approximately 2 m²/min was able to be achieved for a composition comprising white sand. In other embodiments where a lower viscosity, lower particulate content composition is to be applied such as the composition described in Example 5 below, a spray rate of over 10 m²/min could be achieved using an airless spray applicator. Example 1

[0050] A cementitious mixture comprising 50% w/w calcium sulphoaluminate, 30% w/w Portland cement, and 20% w/w white sand was mixed with a styrene acrylic latex (Rovene 6521 supplied by Mallard Creek) in a ratio with the cementitious mixture of 1.2:1. The resulting slurry was observed to have a pot life of approximately one hour. The slurry was applied to a concrete substrate and, upon drying, was found to have an excellent bond to the concrete substrate with failure of the membrane layer only occurring at very high pull forces. The dried composition was found to have very good wearability and resistance of up to 10 metres head pressure. The performance of a composition according to Example 1 are summarised in Table 1 below.

Table 1: Performance testing of a composition according to Example 1

[0051] The composition was able to be sprayed onto a building substrate using a pressurised bottom outlet spray unit using a 3mm spray nozzle attached to a single phase compressor. This method provided a spray speed of approximately 2 m²/min. Reliability was excellent and a desired coat thickness of 2mm (wet) was achievable with very little over spray. A second coat was able to be applied within an hour of applying the first layer, providing a 2mm (wet)/1.5mm (dry) coating.

Example 2

[0052] A cementitious mixture comprising 50% w/w calcium sulphoaluminate, and 50% w/w anhydrite was mixed with a styrene acrylic latex (Rovene 6521 supplied by Mallard Creek) in a ratio with the cementitious mixture of 1.2:1. The resulting slurry was observed to have a pot life of approximately two hours. The slurry was applied to a concrete substrate and, upon drying, was found to have an excellent bond to the concrete substrate and provide a smooth appearance.

Example 3

[0053] A cementitious mixture comprising 50% w/w calcium sulphoaluminate, 25% w/w Anhydrite, and 25% w/w fine sand was mixed with a styrene acrylic latex (Rovene 6521 supplied by Mallard Creek) in a ratio with the cementitious mixture of 1.2:1. The resulting slurry was observed to have a pot life of approximately two hours. The slurry was applied to a concrete substrate and, upon drying, was found to have an excellent bond to the concrete substrate.

Example 4

[0054] A cementitious mixture comprising 50% w/w calcium sulphoaluminate, 25% w/w Anhydrite, and 25% w/w fly ash was mixed with a styrene acrylic latex (Rovene 6521 supplied by Mallard Creek) in a ratio with the cementitious mixture of 1.2:1. The resulting slurry was applied to a concrete substrate and, upon drying, was found to have a good bond to the concrete substrate. Example 5

[0055] A cementitious mixture comprising 30 parts (31.6% w/w) calcium

sulphoaluminate, and 65 parts (68.4% w/w) Portland cement was mixed with 127.5 parts of a styrene acrylic latex (Rovene 6521 supplied by Mallard Creek) and 7.5 parts water. It was found that the absence of sand and increased latex to cementitious mixture ratio of 1.34:1 provided a composition with improved stability and slightly reduced viscosity. The composition was able to be sprayed on a building substrate using an airless spray applicator at a rate of over 10 m²/min. An Atomex XM-45 airless spray applicator, modified to reduce pulsing, was used to apply the composition to the building substrate. The method was found to provide a very high quality finish with no over spray.

Example 6

[0056] A waterproofing composition was prepared in accordance with Table 2 below. Elongation testing of the resulting composition at 7 days provided the following elongation results: 315% (no immersion); 281% (immersion in bleach); 284%

(immersion in water); and 189% (immersion in detergent).

Table 2: Waterproofing composition according to Example 6

[0057] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A composition for waterproofing a building substrate, comprising: a cementitious mixture comprising calcium sulfoaluminate and at least one other cementitious material; and latex, wherein the ratio of latex to cementitious mixture is at least 1.2:1.

2. A composition according to claim 1, wherein the at least one cementitious material is selected from the group consisting of: Portland cement, anhydrite, gypsum, fly ash, quick dry cement, or combinations thereof.

3. A composition according to claim 1 or claim 2, wherein the latex is selected from the group consisting of: styrene acrylic latex, natural rubber latex, polybutadiene latex, polychloroprene latex, polyvinyl acetate latex, nitrile latex, or combinations thereof.

4. A composition according to any one of the preceding claims, wherein the latex has a glass transition temperature of less than or equal to around 0°C.

5. A composition according to any one of the preceding claims, further comprising one or more additives selected from the group consisting of: sand, pigment, defoamer, coalescing agents, biocides, thickeners, stabiliser, fibers, thickeners, water, or combinations thereof.

6. A composition according to any one of the preceding claims, further comprising a retarder.

7. A composition according to claim 6 wherein the retarder comprises tartaric acid.

8. A composition according to any one of the preceding claims, wherein the cementitious mixture comprises at least 25% w/w calcium sulfoaluminate.

9. A composition according to claim 8, wherein the cementitious mixture comprises at least 50% w/w calcium sulfoaluminate.

10. A composition according to any one of claims 1 to 9, wherein the ratio of calcium sulfoaluminate to the at least one other cementitious material is at least 15:1.

11. A composition according to any one of claims 1 to 9, wherein the ratio of the at least one other cementitious material to the calcium sulfoaluminate is at least 15:1.

12. A composition for waterproofing a building substrate, comprising: a cementitious mixture comprising calcium sulfoaluminate and at least one other cementitious material; and latex having a glass transition temperature of less than or equal to around 0°C, wherein the ratio of latex to cementitious mixture is at least 1.2:1.

13. A composition according to claim 12, further comprising tartaric acid.

14. A composition according to claim 12 or claim 13, wherein the ratio of calcium sulfoaluminate to the at least one other cementitious material is at least 20:1.

15. A composition for waterproofing a building substrate, comprising:

50-75% w/w latex;

30-45% w/w calcium sulfoaluminate; and

1-5% w/w other cementitious material.

16. A composition according to claim 15, further comprising 0.05-2% tartaric acid.

17. A composition according to claim 15 or claim 16, wherein the latex has a glass transition temperature of less than or equal to around 0°C.

18. A composition according to any one of claims 15 to 17, further comprising one or more additives selected from the group consisting of: sand, pigment, defoamer, coalescing agents, biocides, thickeners, stabiliser, fibers, thickeners, water, or combinations thereof.

19. A method of forming a waterproofing membrane on a building substrate, the method comprising: forming a slurry according to the composition of any one of the preceding claims; applying a layer of the slurry to a surface of the building substrate; and allowing the layer of slurry to dry, thereby forming a waterproofing membrane adhered to the surface of the building substrate.

20. A method according to claim 19, wherein the layer of slurry is applied to the surface of the building substrate using an airless spray system.