Novel roofing composition

Abstract

[Refer to original abstract doc for image] A hot-melt waterproofing composition, suitable for forming a waterproof layer, comprising a bitumen, a biogenic binder and a filler. The bitumen is present a

Description

The present invention relates to a hot-melt waterproofing system and to a hot-melt waterproofing composition for use in the same. Background Hot-melt waterproofing systems are well known and are often employed to provide a waterproof layer to flat roofs of buildings. Throughout this specification, the term “waterproof layer” and like terms will be used to mean any layer that will prevent, or at least limit, ingress of water between the layer and a substrate to which it is applied. In the context of flat roofs of buildings, a waterproof layer will therefore prevent, or at least limit, ingress of water through the roof and down into the structure of the building below. In the case of a flat roof which is to be waterproofed, an exterior-facing surface of the roof is typically primed with a suitable primer material, a waterproofing layer is applied over the primer layer, and finally a protective top layer is applied to complete and prolong the lifetime of the waterproofing system. In existing systems, it is known to form the waterproof layer from a polymer-modified bitumen compound. Throughout this specification, “bitumen” refers to a hydrocarbon product that is petrochemically-derived, being produced from heavy crude oil during a refining process. In particular, it is produced by removing lighter fractions such as liquid petroleum gas, petrol and diesel. This is sometimes referred to as “refined bitumen” or, especially in North America, “asphalt cement” or “asphalt”. A polymer-modified bitumen compound is a bituminous binder compound, certain properties of which, such as its elasticity, adhesive strength and / or cohesive strength, being modified by the inclusion of one or more chemical agents. These agents are typically suspended or dissolved in the bitumen and, aside from one or more polymers, may include oil, wax and binders / fillers such as limestone flour and rubber crumb. The polymer-modified bitumen compound, which is a semi-solid at ambient temperature and ambient pressure, is heated to increase its viscosity and workability and applied whilst hot to the primer layer. By “ambient temperature” and “ambient pressure” are meant the local temperature and local pressure respectively of the surround environment, e.g. 25°C and 1 atmosphere (101.325 kPa). For a typical building, ambient temperature and ambient pressure will depend on one or more of geographical location, time of day, weather and season; ambient temperatures may typically be in the range of from about -40°C to about +40°C, whilst ambient pressure may typically be in the range of from about 101.325 kPa to about 97.718 kPa. Typically, the polymer-modified bitumen compound is heated to a temperature of around 160°C or above. Such prior waterproofing systems have been found to be extremely successful when installed, e.g. on a flat roof of a building, in providing a substantially waterproof layer, which is bonded to the underlying roof substrate to prevent ingress of water between the layer and the roof substrate and thus down into the structure of the building below. However, there are a number of features of such waterproofing systems which could be improved upon, as will be discussed in more detail below. Current hot-melt waterproofing systems are reliant on high contents of petrochemical-derived bitumen, leading to a high embedded carbon footprint. It is therefore an object of embodiments of the present invention to address the above problems and disadvantages and to at least mitigate, if not obviate, some or all of the same. Summary of the Invention A first aspect of the present invention relates to a hot-melt waterproofing composition, suitable for forming a waterproof layer, comprising a bitumen, a biogenic binder and a filler. The inclusion of the biogenic binder reduces the quantity of bitumen within the composition, thereby reducing the carbon footprint of the composition as the former has a much lower carbon footprint. Blends of the biogenic binder and bitumen have been used for road applications (e.g. asphalt), but have different chemical and physical properties to pure bitumen. It has surprisingly been found that a portion of the bitumen from a roofing composition can be substituted for a biogenic binder without negatively impacting its effectiveness. The biogenic binder may be a biogenic tar or pitch. The biogenic binder may be present in an amount from about 1 to about 40% by weight of the hot-melt waterproofing composition, preferably from about 2 to about 30% by weight, more preferably from about 3 to about 20% by weight, further preferably from 4 to about 15% by weight, most preferably from about 5 to about 10% by weight such as about 7.5% by weight. The bitumen may be present in an amount from about 20 to about 60% by weight, preferably from about 30 to about 50% by weight, most preferably from about 35 to about 45% by weight of the hot-melt waterproofing composition, such as about 40% by weight. The filler may be selected from stone particles or aggregate materials such limestone flour. The filler may be present in an amount of from about 30 to about 50% by weight of the hot-melt waterproofing composition. The hot-melt waterproofing composition may further comprise a modifying polymer. The modifying polymer may be a styrene-butadiene-styrene copolymer. The modifying polymer may be present in an amount of from about 2 to about 6% by weight of the hot-melt waterproofing composition. The hot-melt waterproofing composition may further comprise a process wax. The process wax may be a fatty acid derived process wax, such as ethylene bisstearamide. The process wax may be present in an amount of from about 0.1 to 5% by weight of the hot-melt waterproofing composition. The hot-melt waterproofing composition may further comprise a rubber crumb. The rubber crumb may comprise from about 1 to about 4% by weight of the hot-melt waterproofing composition. The hot-melt waterproofing composition may further comprise a herbicide. The herbicide may comprise from about 0.01 to about 0.5% by weight of the hot-melt waterproofing composition. The hot-melt waterproofing composition may be a structural waterproofing composition. The structural waterproofing composition may comprise filler in an amount of from about 70 to about 90 % by weight, preferably from about 80 to about 90 % by weight. The filler may comprise a mixture of particle sizes, optionally wherein the structural waterproofing composition comprises larger particles in an amount of from about 10 to about 30 % by weight and smaller particles in an amount of from about 60 to about 80% by weight. The bitumen may comprise from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight of the structural waterproofing composition. The biogenic binder may comprise of from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight of the structural waterproofing composition. A second aspect of the present invention relates to a method of applying a waterproof layer to a substrate, said method consisting of the steps of: providing a hot-melt waterproofing composition according to the first aspect of the present invention at ambient temperature; heating the hot-melt waterproofing composition to a working temperature; applying a layer of the heated hot-melt waterproofing composition whilst hot to the substrate; and allowing said layer to cool to ambient temperature. The substrate may comprise a flat roof of a building. The substrate may be primed with a suitable priming material prior to the application of the layer of waterproofing material. One or more protective layers may be applied over the layer of waterproofing material. The working temperature may be in the range of from about 150°C to about 250°C. Each of the one or more layers of the waterproofing material may have a thickness of between about 2 mm and about 4 mm. The overall thickness of the one or more layers of the waterproofing material may be between about 4 mm and about 8 mm. In embodiments, the hot-melt waterproofing composition is a structural waterproofing composition and / or each of the one or more layers thereof has a thickness of between about 5 mm and about 50 mm, preferably between about 10 mm and about 40 mm. A third aspect of the present invention relates to a method of preparation of a hot-melt waterproofing composition according to the first aspect of the present invention, said method comprising the steps of: providing a bitumen; heating the bitumen to a mixing temperature; providing a biogenic binder; heating the biogenic binder to a mixing temperature; combining the biogenic binder and the bitumen to provide a binder substance; adding a filler to the binder substance; mixing the filler and binder substance to distribute the filler throughout the binder substance to form the hot-melt waterproofing composition; and allowing the hot-melt waterproofing composition to cool to ambient temperature. The step of providing the binder substance may comprise the addition of one or more additives to the binder substance. According to a fourth aspect of the present invention, there is a provided a waterproof layer prepared by cooling an at least partially molten portion of a hot-melt waterproofing composition according to the first aspect of the present invention. In embodiments, the layer is provided by the method according to the second aspect of the present invention. According to a fifth aspect of the present invention, there is a provided a structural waterproof layer prepared by cooling an at least partially molten portion of a structural waterproofing composition according to the first aspect of the present invention. In embodiments, the layer is provided by the method according to the second aspect of the present invention. Brief Description of the Drawings Fig. 1A shows an FTIR spectrum for a blend of bitumen and biogenic binder. The arrows indicate some of the additional peaks in the spectrum belonging to the biogenic binder. Fig. 1B shows an FTIR spectrum for a bitumen. Fig. 1C shows and FTIR spectrum for a bitumen. Detailed Description A first aspect of the present invention relates to a hot-melt waterproofing composition comprises a bitumen, a biogenic binder, and a filler. At ambient conditions, bitumen is an extremely viscous liquid, acting as a solid except over extremely large time scales (e.g. decades) where its liquid characteristics become apparent. Bitumen is derived from petrochemical extraction and oil refining industries and comprise high molecular weight hydrocarbons, which are defined as maltenes or asphaltenes depending on whether or not they dissolve in pentane or heptane. As products derived from crude oil, the composition of bitumens varies depending on their source. Typically, bitumens comprise 5 to 25% by weight asphaltenes and 65 to 95% maltenes. Due to this variation, rather than being chemically defined, bitumens are classified on the basis of their physical parameters such as penetration at 25°C (EN 1426:2015), softening point (EN 1427:2015), and penetration index (EN 12591:2009). Such classification is useful to applications where the physical characteristics of the bitumen are paramount, such as in asphalt for road and paving applications. However, these classifications are less useful for applications such as roofing which have very different physical requirements. Accordingly, different bitumens achieving the same classification, although interchangeable for paving and road applications, are unlikely to be interchangeable for roofing applications. This extends to bitumen alternatives, which are intended to replace bitumens for paving and road applications and are thought to be unlikely to be suitable bitumen replacements for roofing applications. The bitumen may be present in the hot-melt waterproofing composition in an amount from about 20 to about 60% by weight, preferably from about 30 to about 50% by weight, most preferably from about 35 to about 45% by weight of the hot-melt waterproofing composition, such as about 40% by weight. The biogenic binder is preferably a biogenic tar or pitch, such as those derived from plants. For example, wood tars such as pine tar or birch tar. A preferred biogenic binder is tall oil pitch. The biogenic binder may be present in the hot-melt waterproofing composition in an amount from about 1 to about 40% by weight of the hot-melt waterproofing composition, preferably from about 2 to about 30% by weight, more preferably from about 3 to about 20% by weight, further preferably from 4 to about 15% by weight, most preferably from about 5 to about 10% by weight such as about 7.5% by weight In comparison with prior art hot-melt waterproofing compositions, the biogenic binder takes the place of a portion of the bitumen. This reduces the embodied carbon of the hot-melt waterproofing system. Surprisingly, it has been found that this substitution is not detrimental to the performance of the hot-melt waterproofing composition. The bitumen and biogenic binder may be provided together in a mixture. One example of such a mixture is Shell Bitumen CarbonSink™. Suitable filler materials are inert particulates and may include stone or aggregate materials such as limestone flour. The hot-melt waterproofing composition may comprise filler material in an amount of from about 30 % to about 50 % by weight, preferably from about 33% to about 48 % by weight and more preferably from about 35 % to about 45 % by weight, such as about 44% by weight. The hot-melt waterproofing composition may comprise a modifying polymer. The modifying polymer may be, for example, styrene-butadiene-styrene (SBS). Such a polymer may be added to increase the low temperature flexibility of the waterproofing material. Preferably, the modifying polymer may be comprised in the waterproofing material in an amount of from about 2 % to about 6 % by weight, preferably from about 2.5 % to about 5.5 % by weight and most preferably from about 3 % to about 5 % by weight. The hot-melt waterproofing composition may further comprise a process wax. Suitable process waxes may be, or include, paraffinic process waxes such as: Sasobit™ produced by Sasol; or CrodaWax™ 140 produced by Croda Internationanl plc. Alternatively, the process wax may be, or include, fatty acid derived process waxes, such as fatty acid bis-amides, such as PALMOWAX EBS (ethylene bis-stearamide) or PALMOWAX EBO (ethylene bis-oleamide). One or more process waxes may be added to the hot-melt waterproofing composition to improve the overall flow of the hot-melt waterproofing composition at relatively high temperature, i.e. of the order of 100°C and above. The process wax may additionally or alternatively improve the stability of the hot-melt waterproofing composition at relatively low temperature, i.e. of the order of 50°C and below. The hot-melt waterproofing composition may comprise the process wax in an amount of from about 0.1 % to about 5 % by weight, preferably from about 0.3 % to about 4 % by weight, and most preferably from about 0.5 % to about 3 % by weight. The hot-melt waterproofing composition may further comprise rubber crumb. Rubber crumb may be incorporated into the hot-melt waterproofing composition to improve the overall flexibility of the hot-melt waterproofing composition at mid-range temperatures. Mid-range temperatures may be between -5°C and 5°C. The rubber crumb may be comprised in the hot-melt waterproofing composition in an amount of from about 1 % to about 4 % by weight, preferably from about 1.2 % to about 3.8 % by weight and most preferably from about 1.5 % to about 3.5 % by weight. The hot-melt waterproofing composition may further comprises a herbicide, such as mecaprop (4-chloro-2-methylphenoxy)-propionic acid octyl ester; Preventol B5), 2,4-D (2,4-dichlorophenoxyacetic acid), dicamba (3,6-dichloro-2-methoxybenzoic acid), or MCPA (2-methyl-4-chlorophenoxyacetic acid). The herbicide serves to limit, or prevent, the growth of plants through the hot-melt waterproofing composition, which could compromise its effectiveness by providing a pathway for the transit of water. The herbicide may be present in the hot-melt waterproofing composition in an amount of from about 0.01 to about 0.5% by weight, preferably from about 0.1 to about 0.3% by weight, more preferably about 0.2% by weight. In embodiments, the hot-melt waterproofing composition is a structural waterproofing composition. Such structural waterproofing compositions have greater physical strength than the aforementioned hot-melt waterproofing compositions, allowing them to be used in applications where trafficking of the waterproofed substrate is expected, either by foot or by vehicular traffic (e.g. rooftop plazas or rooftop carparks). This greater strength is achieved by using a higher proportion of filler material and, preferably, a combination of filler materials with different sizes. The structural waterproofing composition may comprise from about 70 to about 90 % by weight of filler, preferably from about 80 to about 90 % by weight of the filler. The filler may be selected from stone particles or aggregate materials. Preferably, the filler comprises particulate materials of different sizes. For example, the filler may comprise a mixture of larger particles (with sizes above 1 mm) and smaller particles (with sizes below 1 mm). Particle sizes may be determined by sieving. In embodiments comprising particles of different sizes, it is preferred that the larger particles comprise from about 10 to about 30 % by weight of the composition (preferably from about 13 to about 25 % by weight of the composition) and the smaller particles comprise from about 60 to about 80 % by weight of the composition (preferably from about 63 to about 75 % by weight of the composition). It will be understood that the proportions of the large and small filler may be varied depending on the load that the structural waterproofing composition is intended to bear, with the proportion of large filler increasing with intended load. As the proportion of filler is increased for the structural waterproofing composition, the proportion each of the bitumen and biogenic binder is decreased accordingly. The bitumen may be present in an amount of from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight. The biogenic binder may be present in an amount of from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight. The proportions of the other components may also decrease proportionately with the bitumen and biogenic binder contents. For example, the proportion of the process wax may decrease to an amount from about 0.01 to about 0.5 % by weight, preferably from about 0.05 to about 0.2 % by weight, more preferably from about 0.07 to about 0.09 % by weight, such as about 0.08 % by weight. According to a second aspect of the present invention there is provided a method of applying a waterproof layer to a substrate, said method consisting essentially of the steps of: providing the hot-melt waterproofing composition according to the first aspect of the present invention at ambient temperature; heating the hot-melt waterproofing composition to a working temperature; applying a layer of the heated hot-melt waterproofing composition whilst hot to the substrate; and allowing said layer to cool to ambient temperature. The method according to the second aspect of the present invention may incorporate any or all of the features of the hot-melt waterproofing composition according to the first aspect of the present invention as desired or required. In a preferred embodiment, the substrate may comprise a flat roof of a building. Optionally, the substrate may be primed with a suitable priming material prior to the application of the layer of waterproofing material. The priming step may preferably occur immediately prior to application of the layer of heated waterproofing material (in sequence at least, if not also temporally), i.e. to the exclusion of any intermediate step(s). Optionally, one or more protective layers may be applied over the waterproof layer. The protecting step may preferably occur immediately subsequent to application of the layer of heated waterproofing material (in sequence at least, if not also temporally), i.e. to the exclusion of any intermediate step(s). Preferably the working temperature is any suitable temperature at which the waterproofing material is sufficiently workable so that it can be applied as a layer to the substrate which will be of substantially uniform thickness at ambient temperature. The working temperature may be dependent upon the ambient temperature. The working temperature may be in the range of from about 150°C to about 250°C, preferably from about 160°C to about 200°C, and further preferably from about 160°C to about 180°C. Most preferably, the working temperature is around 160°C. Any number of layers of the hot-melt waterproofing composition may be applied to the substrate as desired or required, although as few as a single layer may suffice to impart the desired waterproofing. Preferably, the one or more layers of the hot-melt waterproofing composition may be of substantially uniform thickness. Each of the one or more layers of the hot-melt waterproofing composition may have a thickness of between about 2 mm and about 4 mm. The overall thickness of the one or more layers of the hot-melt waterproofing composition may be between about 4 mm and about 8 mm. Alternatively, where the hot-melt waterproofing composition is a structural waterproofing composition, each of the one or more layers thereof may have a thickness of between about 5 mm and about 50 mm, preferably between about 10 mm and about 40 mm. In one preferred embodiment, two layers of the hot-melt waterproofing composition may be applied to the substrate, each layer preferably having a thickness of around 3 mm. In certain embodiments, one or more layers of the structural waterproofing composition may be lain, followed by one or more layers of the hot-melt waterproofing composition. This produces a roofing structure with the highest level of waterproofing and structural strength. According to a third aspect of the present invention there is provided a method of preparation of a hot-melt waterproofing composition according to the first aspect of the present invention, said method comprising the steps of: providing a bitumen; heating the bitumen to a mixing temperature; providing a biogenic binder; heating the biogenic binder to a mixing temperature; combining the biogenic binder and the bitumen to provide a binder substance; adding a filler to the binder substance; mixing the filler and binder substance to distribute the filler throughout the binder substance to form the hot-melt waterproofing composition; and allowing the hot-melt waterproofing composition to cool to ambient temperature. The biogenic binder and bitumen may be heated prior to mixing. Alternatively, they may be combined and then mixed. Further alternatively, a first one of the bitumen and the biogenic binder may be heated and the second of the bitumen and the biogenic binder added, such that the second is heated as it is mixed. The method according to the third aspect of the present invention may incorporate any or all of the features of the first and second aspects of the present invention as desired or required. Once mixed, the hot-melt waterproofing composition may be poured into one or more moulds before being cooled to ambient temperature. Once cooled, the moulded hot-melt waterproofing composition may be released from its mould and stored for future use or immediately transported to a site for use. As herein described, the hot-melt waterproofing composition may comprise one or more additives. The step of providing a hot-melt waterproofing composition may further comprise the addition of one or more of said additives to the hot-melt waterproofing composition. The binder substance may comprise an organic petrochemical fraction such as, for example, bitumen. The step of providing a binder substance may involve the heating of the binder to the mixing temperature and adding one or more additives thereto whilst hot. The one or more additives may be of the type hereinbefore described, including: a modified polymer such as, for example, SBS; a process wax; a filler material such as limestone flour; and / or rubber crumb. A hot-melt waterproofing composition according to the first aspect of the invention may be suitable for application using the method according to the second aspect of the present invention. A hot-melt waterproofing composition according to the first aspect of the invention may be formed using the method according to the third aspect of the present invention. According to a fourth aspect of the present invention, there is a provided a waterproof layer prepared by cooling an at least partially molten portion of a hot-melt waterproofing composition according to the first aspect of the present invention. In embodiments, the layer is provided by the method according to the second aspect of the present invention. By at least partially molten is it meant that the composition is heated such that it is sufficiently workable to be applied to the substrate. According to a fifth aspect of the present invention, there is a provided a structural waterproof layer prepared by cooling an at least partially molten portion of a structural waterproofing composition according to the first aspect of the present invention. In embodiments, the layer is provided by the method according to the second aspect of the present invention. By at least partially molten is it meant that the composition is heated such that it is sufficiently workable to be applied to the substrate. For a better understanding, the present invention will now be more particularly described, byway of non-limiting example only. Examples Blended Bitumen and Biogenic Binder A blended bitumen and biogenic binder (Shell Bitumen CarbonSink) and two samples of pure bitumen (Shell Bitumen 70 / 100 and Imperial Bitumen 70 / 100) were analysed by FTIR, the softening point determined (using softening point ring and ball method in accordance with BS EN 1427:2015), and the needle penetration tested (at 25°C in accordance with BS EN 1426:2015). Fig. 1A shows the FTIR spectrum for the blended bitumen and biogenic binder, with Figs. 1B and 1C showing the FTIR spectra for two samples of bitumen. From the spectra, it can be seen that the blended bitumen and biogenic binder is chemically distinct from the pure bitumen samples, having additional peaks at... The results show that the biogenic binder is chemically distinct from the bitumen. Softening Point (°C) Penetration depth Shell Bitumen CarbonSink 43.8 98 Shell Bitumen 70 / 100 46.9 79 Imperial Bitumen 46.4 80 70 / 100 The results show that the blended bitumen and biogenic binder have different physical properties compared to the pure bitumen samples. Overall, the inclusion of the biogenic binder is shown to alter the properties of the bitumen composition. Exemplary Roofing Composition In one exemplary embodiment, the hot-melt waterproofing composition comprises: Component (function) Quantity (% by weight) Palmowax EBS (process wax) 0.5 to 1 Limestone Flour (Filler) 35 to 45 SBS 401 Powder (modifying polymer) 4 to 5 Bitumen 35 to 45 Biogenic binder 5 to 10 Fine Crumb Tb420-180 (rubber crumb) 2 to 2.5 Optionally - Preventol B5 (herbicide) 0.01 to 0.5 Mechanical Testing In a first test according to BS EN 15818:2011, two square samples of the exemplary roofing composition were prepared, measuring 100 mm x 100 mm and with a 3 mm thickness. These samples were stored vertically at a temperature of 70°C for a period of two hours. No movement (i.e. sliding or slumping) of the material was observed. In a second test according to BS EN 15813:2011, five rectangular samples of the exemplary roofing composition were prepared, measuring 200 mm x 50 mm and with a 3 mm thickness. These samples were stored flat at 0°C for a period of one hour. The cooled samples were bent around a mandrel with a diameter of 30 mm, the bending occurring at a constant rate over a period of three seconds. No damage (e.g. cracking) was observed for any of the samples. These examples show that the roofing composition possesses the required physical properties for use in roofing applications, being resistant to movement under its own weight at elevated temperatures and remaining flexible at low temperatures. Weathertightness The exemplary roofing composition was used to create a test roof. The test roof was subjected to a six metre head of water for a 24 hour period, which was successfully resisted. This example shows that the roofing composition possesses the required weathertightness for use in roofing applications. Exemplary Structural Roofing Composition In a further exemplary embodiment, the hot-melt waterproofing composition is a structural hot-melt waterproofing composition and comprises: Component (function) Quantity (% by weight) Palmowax EBS (process wax) 0.05 to 0.2 3mm Limestone Grit (Filler) 10 to 30 45 / 55* Coarse Limestone Powder (Filler) 60 to 80 Bitumen 3 to 10 Biogenic binder 3 to 10 Optionally - Preventol B5 (herbicide) 0.01 to 0.5 *Refers to 45 to 55 % by weight of the powder passing a 75 micron sieve. The exemplary structural roofing composition meets the physical requirements of a structural roofing composition (in terms of physical robustness and waterproofness), while achieving a reduced carbon footprint and, unexpectedly, improved laying properties.

Claims

1. A hot-melt waterproofing composition, suitable for forming a waterproof layer, comprising a bitumen, a biogenic binder and a filler.

2. The hot-melt waterproofing composition of claim 1, wherein the biogenic binder is a biogenic tar or pitch and / or is present in an amount from about 1 to about 40% by weight of the hot-melt waterproofing composition, preferably from about 2 to about 30% by weight, more preferably from about 3 to about 20% by weight, further preferably from 4 to about 15% by weight, most preferably from about 5 to about 10% by weight such as about 7.5% by weight.

3. The hot-melt waterproofing composition of any preceding claim, wherein the bitumen is present in an amount from about 20 to about 60% by weight of the hot-melt waterproofing composition, preferably from about 30 to about 50% by weight, most preferably from about 35 to about 45% by weight, such as about 40% by weight.

4. The hot-melt waterproofing composition of any preceding claim, wherein the filler is selected from stone particles or aggregate materials such limestone flour.

5. The hot-melt waterproofing composition of claim 4, wherein the filler is present in an amount of from about 30 to about 50% by weight of the hot-melt waterproofing composition.

6. The hot-melt waterproofing composition of any preceding claim, further comprising a modifying polymer, optionally wherein the modifying polymer is a styrene-butadiene-styrene copolymer and / or is present in an amount of from about 2 to about 6% by weight of the hot-melt waterproofing composition.

7. The hot-melt waterproofing composition of any preceding claim, further comprising a process wax.

8. The hot-melt waterproofing composition of claim 8, wherein the process wax is a fatty acid derived process wax, such as ethylene bis-stearamide, and / or is present inan amount of from about 0.1 to 5% by weight of the hot-melt waterproofing composition.

9. The hot-melt waterproofing composition of any preceding claim, further comprising a rubber crumb, optionally wherein the rubber crumb comprises from about 1 to about 4% by weight of the hot-melt waterproofing composition.

10. The hot-melt waterproofing composition of any preceding claim, further comprising a herbicide, optionally wherein the herbicide comprises from about 0.01 to about 0.5% by weight of the hot-melt waterproofing composition.

11. The hot-melt waterproofing composition of any preceding claim, wherein the hot-melt waterproofing composition is a structural waterproofing composition.

12. The structural waterproofing composition of claim 11, wherein the structural waterproofing composition comprises filler in an amount of from about 70 to about 90 % by weight, preferably from about 80 to about 90 % by weight.

13. The structural waterproofing composition of claim 11 or claim 12, wherein the filler comprises a mixture of particle sizes, optionally wherein the structural waterproofing composition comprises larger particles in an amount of from about 10 to about 30 % by weight and smaller particles in an amount of from about 60 to about 80% by weight.

14. The structural waterproofing composition of any of claims 11 to 13, wherein the bitumen comprises of from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight of the structural waterproofing composition.

15. The structural waterproofing composition of any of claims 11 to 14, wherein the biogenic binder comprises of from about 1 to about 20 % by weight, preferably from about 2 to about 15 % by weight, more preferably from about 3 to about 10 % by weight, most preferably from about 5 to about 8 % by weight, such as about 6 % by weight of the structural waterproofing composition.

16. A method of applying a waterproof layer to a substrate, said method consisting of the steps of:providing a hot-melt waterproofing composition as claimed in any one of claims 1 to 15 at ambient temperature;heating the hot-melt waterproofing composition to a working temperature;applying a layer of the heated hot-melt waterproofing composition whilst hot to the substrate; andallowing said layer to cool to ambient temperature.

17. A method according to claim 16, wherein the substrate comprises a flat roof of a building.

18. A method according to claim 16 or claim 17, wherein the substrate is primed with a suitable priming material prior to the application of the layer of waterproofing material and / or wherein one or more protective layers are applied over the layer of waterproofing material.

19. A method according to any one of claims 16 to 18, wherein the working temperature is in the range of from about 150°C to about 250°C.

20. A method according to any one of claims 16 to 19, wherein:(i) each of the one or more layers of the waterproofing material has a thickness of between about 2 mm and about 4 mm; and / or(ii) an overall thickness of the one or more layers of the waterproofing material is between about 4 mm and about 8 mm.

21. A method according to any one of claims 16 to 20, wherein the hot-melt waterproofing composition is a structural waterproofing composition and / or each of the one or more layers thereof has a thickness of between about 5 mm and about 50 mm, preferably between about 10 mm and about 40 mm.

22. A method of preparation of a hot-melt waterproofing composition as claimed in any one of claims 1 to 15, said method comprising the steps of: providing a bitumen;heating the bitumen to a mixing temperature;providing a biogenic binder;heating the biogenic binder to a mixing temperature;combining the biogenic binder and the bitumen to provide a binder substance;5 adding a filler to the binder substance;mixing the filler and binder substance to distribute the filler throughout the binder substance to form the hot-melt waterproofing composition; andallowing the hot-melt waterproofing composition to cool to ambient temperature.10 23. A method according to claim 22, wherein the step of providing the bindersubstance comprises the addition of one or more additives to the binder substance.

24. A waterproof layer prepared by cooling an at least partially molten portion of a hot-melt waterproofing composition as defined in any of claims 1 to 10, optionally using 15 the method of any of claims 16 to 20.

25. A structural waterproof layer prepared by cooling an at least partially molten portion of a structural waterproofing composition as defined in any of claims 11 to 15, optionally using the method of any of claims 16 to 21.21

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