Composition of mortar and mortar for passive fire protection of a surface coated with it

Abstract

A composition of mortar, a mortar comprising said composition and a surface coated with said mortar, with a low density, are provided for passive fire protection.

Description

[0001] COMPOSITION OF MORTAR AND MORTAR FOR PASSIVE FIRE PROTECTION OF A SURFACE COATED WITH IT

[0002] Cross-Reference to Related Applications This Patent Application claims priority from Italian Patent Application No . 102024000023532 filed on October 22, 2024, the entire disclosure of which is incorporated herein by reference .

[0003] Field

[0004] This invention relates to a composition of mortar and a mortar made from it . This invention also relates to a surface coated with said mortar for fire protection, especially passive fire protection. This invention is preferably used in civil and industrial construction, for example, said mortar coats load-bearing and non-load-bearing masonry or steel structures, flues and air conditioning ducts .

[0005] Description of the Prior Art

[0006] Many materials used, for example, in construction quickly lose their strength and give way during a fire . As an obvious consequence, the structural collapse of infrastructure such as, for example, skyscrapers and oil rigs, following a fire can be catastrophic in terms of fire escalation, loss of human life and economic damage .

[0007] In other cases, the lack of fire protection of flues and air conditioning ducts allows fire to develop and spread to different fire compartments of a building, with even catastrophic consequences in the event of a fire, in terms of fire escalation, loss of human life and economic damage . Take, for example, a hospital, where people have difficulty walking, due to their medical conditions, and therefore have little chance of escaping the spread of flames and smoke .

[0008] Therefore, a coating of said materials with good fire protection increases the time required before the coated structure collapses due to a fire, allowing the fire brigade to perform a more effective and lasting intervention.

[0009] In this regard, cementitious passive fire protection coatings have been known since the 1960s and are still on the market today.

[0010] These products, however, have several limitations in terms of, for example, toxicity, poor workability due to their high density of even more than 450 kg / m3for gypsumbased mortars and more than 700 kg / m3for cement-based mortars, and low coating yield per square metre of surface, resulting in higher product consumption and greater surface area to be coated.

[0011] There is therefore a need for a product that is free from the drawbacks of the prior art so that it can be implemented, for example, in civil and industrial construction to ensure greater fire resistance while using less material .

[0012] Description of the Invention Accordingly, one purpose of this invention is to provide a mortar composition that overcomes the previously described drawbacks of the prior art .

[0013] In particular, one specific purpose of the invention is to provide a mortar, corresponding to the mortar composition with added water, that can be used to coat structures / surf aces in the construction industry, that has a low density, thus being more easily worked, and, at the same time, is non-toxic .

[0014] Consequently, another purpose of this invention is to provide a surface coated with said mortar that exhibits good fire protection and good adhesion, using less mortar .

[0015] Furthermore, the purpose of this invention is to provide a mortar used in a wide range of applications, for example, from civil, commercial and industrial construction to the petrochemical and transport sectors .

[0016] Accordingly, this invention relates to a mortar composition, as set forth in claim 1.

[0017] The invention further relates to a mortar comprising said mortar composition and other components, as defined in claim 10.

[0018] The invention also relates to a surface coated with said mortar as defined in claim 15. The invention additionally relates to the use of said mortar in construction as defined in claim 17.

[0019] Preferred and advantageous features of the invention constitute the subj ect matter of the secondary claims .

[0020] The mortar composition of the invention is specifically characterised by constituents in certain amounts such that this composition is non-toxic and less dense than known compositions .

[0021] Consequently, the mortars of the invention, comprising such compositions, are easily worked as low-density compositions easily mix with water . In addition, the mortars of the invention are not toxic or hazardous to the user and / or the environment and are used without the need for special safety precautions .

[0022] The advantages of the compositions and mortars of the invention are reflected in the coated surface of the invention, which is very thin while maintaining excellent passive fire protection in terms of FRL (Fire Rating Level) for 120 minutes, 3 hours or more . A thin layer of mortar coating a surface of interest results in a lower consumption of mortar in relation to the surface area coated with consequent economic and energy benefits in relation to mortar preparation and use .

[0023] Detailed Description

[0024] Additional features, purposes and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting.

[0025] The mortar composition for passive fire protection of the invention mainly comprises : a binder selected from the group consisting of cement, gypsum, slaked lime and mixtures thereof ; a fire retardant; a cellulose derivative; a vinyl acetate and / or vinyl versatate and / or acrylic ester adhesive compound; a surfactant; and a modified starch.

[0026] In particular, the mortar composition of this invention comprises a binder selected from the group consisting of cement, gypsum, slaked lime and mixtures thereof .

[0027] This binder is present in the mortar composition in percentage by weight (wt . %) ranging between 30% and 70% .

[0028] In a first embodiment of the invention ( for the preparation of a cement-based mortar, that is, where cement is the main component, present in the largest quantity by weight with respect to the other components) , the binder, comprised in the composition, is cement or a mixture of cement and slaked lime . According to this embodiment, the amount of binder in the form of cement or mixture of cement and slaked lime is (% by weight) :

[0029] 20% to 70% of cement, preferably 30-50%, more preferably 35-45%, and

[0030] - 0% to 15%, preferably 3-10%, more preferably 5-9%, of slaked lime . The cement preferably belongs to class 42.5 R according to UNI EN 197 / 1, that is, it has an initial 2-day compressive strength > 20; and a standard 28-day compressive strength > 42.5 < 62.5.

[0031] In a second embodiment of the invention ( for the preparation of a gypsum-based mortar, that is, where gypsum is the main component, present in the largest quantity by weight with respect to the other components) , the binder, comprised in the composition, is gypsum or a mixture of gypsum and cement (with a greater amount of gypsum than cement) . According to this embodiment, the amount of binder in the form of gypsum or mixture of cement and slaked lime is (% by weight) :

[0032] 20% to 70% of gypsum, preferably 30-60%, more preferably 40-50%, and

[0033] - 0% to 13%, preferably 0-10%, more preferably 4-8%, of cement .

[0034] According to this embodiment, the gypsum is preferably scagliola, that is, a fine gypsum used in construction, and the cement belongs to class 32. 5N or 32. 5R according to UNI EN 197 / 1.

[0035] Irrespective of the type of binder, the composition of this invention also comprises a fire retardant selected from the group consisting of vermiculite, pearlite, polystyrene, cork and mixtures thereof to impart good fire protection properties to the mortar and the surface coated therewith of this invention.

[0036] "Fire retardant" refers to a material that is both fully incombustible and partially incombustible .

[0037] The fire retardant is present in the mortar composition in quantities in percentage by weight ranging between 30% and 60%, preferably between 35% and 55%, more preferably between 35% and 50% .

[0038] In a preferred embodiment of the invention, the flame retardant is vermiculite .

[0039] The vermiculite is preferably fine expanded vermiculite with a density ranging between 90 and 110 kg / m3, preferably between 95 and 105 kg / m3, for example around 100 kg / m3.

[0040] In another embodiment of the invention, the flame retardant is pearlite or a mixture of pearlite and vermiculite .

[0041] The polystyrene is preferably in the form of spheres, while the cork is preferably in the form of granules . The polystyrene, for example in the form of spheres, and the cork, for example in the form of granules, are preferably used when the binder is mainly gypsum in order to further reduce the density of the composition.

[0042] In addition to the binder and fire retardant, this composition comprises a cellulose derivative that acts as a thickener and / or water-retaining agent . This cellulose derivative therefore allows the mortar and the surface coated with it to increase the binding strength of the mortar and promote adequate setting time .

[0043] The cellulose derivative is present in the mortar composition in quantities in percentage by weight ranging between 0.05% and 1.0%, preferably between 0.15% and 0.80%, more preferably between 0.15% and 0. 60% .

[0044] The cellulose derivative is preferably methylcellulose or one of its derivatives, for example hydroxyethyl methyl cellulose .

[0045] The mortar composition of this invention also comprises an adhesive compound based on vinyl acetate and / or vinyl versatate and / or acrylic ester so as to improve the adhesion of the mortar to the surface it coats .

[0046] This adhesive compound is present in the composition in quantities in percentage by weight ranging between 0.01% and 2.0%, preferably between 0.05% and 2.0%, more preferably between 0.4% and 1.5%, even more preferably between 0.55% and 1.1% .

[0047] For example, using 0.01% by weight of adhesive compound results in a corresponding mortar that is optimally suited for spraying, ensuring a smooth and even application on the substrate ( for example, air ducts or flues) and improving its workability. This adhesive compound is preferably in powder form. The composition also comprises a surfactant to give the mortar and surface coated with it greater fire protection. In particular, this surfactant produces a microscopic amount of air bubbles that are evenly distributed in the mortar . This increases the fire-proofing property of the mortar, lightens it and dilutes it, thus resulting in a higher yield in terms of coverage and fire protection.

[0048] This surfactant is present in the composition in quantities in percentage by weight ranging between 0.02% and 1.2%, preferably between 0.05% and 0.8%, more preferably between 0.05% and 0.5% .

[0049] The surfactant is preferably a fatty acid ethoxylate . For example, the surfactant is a sodium alkyl sulphate, sodium lauryl sulphate, sodium alpha-olefin sulphonate and a fatty acid ethoxylate .

[0050] In addition to the compounds described above, the mortar composition also comprises a modified starch to give the mortar a better consistency, workability, and resistance to pouring, and also to delay the setting time of the mortar .

[0051] This modified starch is present in the composition in quantities in percentage by weight ranging between 0.03% and 1.4%, preferably between 0.03% and 0.8%, more preferably between 0.03% and 0.5% .

[0052] The CAS number of the modified starch is preferably 69234-31-7 .

[0053] For example, the modified starch is chosen from the group consisting of dextrins, glucose and its derivatives, fructose and their combinations .

[0054] The mortar composition is preferably in powder form. It should be noted that the components in the composition of the invention are not toxic or dangerous .

[0055] To prepare the mortar of the invention, the mortar composition described above has water or a water-based solvent and a fine aggregate added to it .

[0056] The amount of water or water-based solvent required to prepare the mortar is sufficient to ensure the mortar has a paste-like viscosity, capable of being applied to a surface using standard techniques such as spreading or, preferably, spraying .

[0057] The amount of water (or water-based solvent) with respect to the dry mortar per 16 kg bag preferably ranges between 30 and 15 litres, preferably between 25 and 20 litres .

[0058] The mortar may also contain other components in addition to the mortar composition, water and fine aggregates, for example retarding agents .

[0059] The mortar composition according to the invention, that is the resulting dry mortar, has, surprisingly, a density less than or equal to 450 kg / m3. Specifically, the density of the (dry) mortar comprising the composition according to the first embodiment, that is, when the binder is cement or a mixture of cement and slaked lime, is less than or equal to 400 kg / m3, preferably less than or equal to 390 kg / m3.

[0060] It should be noted that known, cement-based mortars have a density above 700 kg / m3, for example above 775 kg / m3.

[0061] While the density of the (dry) mortar comprising the composition according to the second embodiment, that is, when the binder is gypsum or a mixture of gypsum and cement, is less than or equal to 300 kg / m3, preferably less than or equal to 290 kg / m3. In fact, gypsum has a specific gravity of 1100 kg / m3' while the specific gravity of cement is higher (equal to 2900 kg / m3) .

[0062] In contrast, gypsum-based mortars are known that have a density above 450 kg / m3, for example above 500 kg / m3.

[0063] The mortar of the invention despite having a low density gives the surface coated with it good mechanical strength and chemical stability.

[0064] According to another aspect of this invention, a surface coated with the above-described mortar is provided.

[0065] Specifically, once the mortar has been prepared from the composition described above, by mixing with water or a water-based solvent, the mortar is applied using known techniques of spraying or trowelling onto a surface, resulting in a surface coated with this mortar . The mortar of the invention, given its characteristics as outlined above, is particularly suitable for application by spraying.

[0066] The mortar of the invention is particularly suitable for providing passive fire protection to metal structures / surfaces , for example steel and concrete .

[0067] Due to the properties of the mortar composition (and, therefore, of the mortar) , including low density, the coated surface provides good fire protection with a thin mortar thickness of 50 mm or less (FRL 120 minutes or for longer times such as 3 or 4 hours) . Thus, for the same surface area coated, less mortar is required than for known mortars to ensure good fire protection.

[0068] According to another aspect of this invention, the use of the above-described mortar for coating a structure / surf ace in civil and industrial construction is also provided.

[0069] Specifically, the mortar of the invention can coat structures / surf aces selected from the group consisting of load-bearing or non-load-bearing masonry or steel structures, ventilation ducts, flues, metal pipes, electrical conduits, plastic ducts, preferably polyvinyl chloride, or metal ducts, preferably copper .

[0070] The mortar can also coat structures / surf aces belonging to the land, air and sea transport sector, as well as the liquid gas storage tank and transport sector.

[0071] EXAMPLES

[0072] The inventive examples and comparisons are given here for illustrative purposes and are not intended to limit the invention .

[0073] The surfaces to which the mortar is applied, according to the invention and comparison, are those of ventilation ducts and flues .

[0074] The gypsum-based mortar according to the invention, designated MALTA_INV, has a dry density of 290 kg / m3.

[0075] The commercially available gypsum-based comparison mortar has a dry density of 501 kg / m3and is designated MALTA_COMP.

[0076] The surfaces coated with MALTA_INV and MALTA_COMP were tested for fire resistance; thus, it was possible to identify the minimum mortar thickness required to ensure the stability of the surface coated with it for 120 minutes in the presence of flames .

[0077] Table 1 shows the degrees of thickness identified and the amount of mortar (by weight per bag) contained in those degrees of thickness for the same coated surface area (such as flues and ventilation ducts) .

[0078] Table 1

[0079] Surface coated with THICKNESS (mm) QUANTITY OF MORTAR (kg / bag) MALTAJNV 50 15 MALTA_COMP 60 20

[0080]

[0081] The data in Table 1 show that, for the same surface area coated, the surface coated with mortar according to the invention (MALTA_INV) is the least thick and, therefore, uses the least mortar while providing the same passive fire protection for 120 minutes .

[0082] This surprising result is confirmed when experimental tests are conducted in accordance with AS 1530.4 : 2014 and evaluated in conjunction with AS 4254.2-2012, by a NATA (National Association of Testing Authorities, Australia, an Australian government body) accredited laboratory. In particular, a layer of MALTA_INV of at least 50 mm applied to a duct system up to 4, 000 mm wide and 2, 000 mm high demonstrated an FRL of 120 / 120 / 120 minutes . Further experiments also confirmed that a flue or ventilation ducts coated with a comparison gypsum-based mortar with a low density (equal to 240 Kg / m3as before vermiculite) still require a thickness of this mortar of at least 61 mm to resist fire for 120 minutes, thus a greater thickness (that is, at least 10 mm greater) than required by the same surface however coated by the mortar according to the invention.

[0083] The results therefore confirm that the mortar composition according to the invention, as well as the mortar and the surface coated by it, fulfil all the purposes of this illustration, such as :

[0084] the composition and products derived from it are not toxic or hazardous to humans and the environment;

[0085] - excellent workability both when mixing with water to produce the mortar and when coating a surface with mortar to create the coated surface;

[0086] - high coating yield per square metre of surface area; - less time in coating a surface;

[0087] - less mortar consumption for the same surface area coated;

[0088] - excellent passive fire protection.

[0089] Lastly, it is clear that further modifications may be made to the mortar compositions according to the invention, and variants produced thereto, without departing from the scope of the attached claims .

Claims

CLAIMS1. A composition of mortar for passive fire protection comprising in weight percentage (wt%) :- from 30% to 70% of a binder selected from the group consisting of cement, gypsum, slaked lime and their mixtures ;- from 30% to 60% of a fire retardant selected from the group consisting of vermiculite, pearlite, polystyrene, cork and their mixtures;- from 0.05% to 1.0% of a cellulose derivative;- from 0.01% to 2.0% of an adhesive compound based on vinyl acetate and / or vinyl versatate and / or acrylic ester, preferably from 0.05% to 2.0%;- from 0.02% to 1.2% of a surfactant; and- from 0.03% to 1.4% of a modified starch.

2. The composition as claimed in claim 1, wherein the cellulose derivative is hydroxyethyl methyl cellulose .

3. The composition as claimed in claim 1 or 2, wherein the surfactant is a fatty acid ethoxylate .

4. The composition as claimed in one of the previous claims, wherein the fire retardant is vermiculite .

5. The composition as claimed in one of the previous claims, wherein the binder is cement or a mixture ofcement and slaked lime .

6. The composition as claimed in claim 5, wherein the composition comprising in weight percentage (wt%) : - from 20% to 70% of cement;- from 0% to 15% of slaked lime;- from 35% to 55% of a fire retardant;- from 0.15% to 0.8% of a cellulose derivative;- from 0.01% to 2.0% of an adhesive compound based on vinyl acetate and / or vinyl versatate and / or acrylic ester, preferably from 0.4% to 1.5%;- from 0.05% to 0.8% of a surfactant; and- from 0.03% to 0.8% of a modified starch.

7. The composition as claimed in one of the previous claims from 1 to 4, wherein the binder is gypsum or a mixture of gypsum and cement .

8. The composition as claimed in claim 7, wherein the composition comprising in weight percentage (wt%) : - from 20% to 70% of gypsum;- from 0% to 13% of cement;- from 35% to 55% of a fire retardant;- from 0.15% to 0.8% of a cellulose derivative;- from 0.01% to 2.0% of an adhesive compound based on vinyl acetate and / or vinyl versatate and / or acrylic ester, preferably from 0.4% to 1.5%;from 0.05% to 0.8% of a surfactant; and - from 0.03% to 0.8% of a modified starch.

9. The composition claimed in one of the previous claims, wherein the composition is in powder form.

10. A mortar for passive fire protection comprising a composition as claimed in one of the claims from 1 to 9 and water .

11. The mortar as claimed in claim 10, wherein the amount of water with respect to a dry mortar per 16 kg bag is between 30 and 15 litres, preferably between 25 and 20 litres .

12. The mortar as claimed in claim 10 or 11, wherein the dry mortar density is less than or equal to 450 kg / m3.

13. The mortar as claimed in claim 12, wherein the dry mortar density is less than or equal to 390 kg / m3when the composition of mortar comprises cement or the mixture of cement and slaked lime as claimed in claim 5.

14. The mortar as claimed in claim 12, wherein the dry mortar density is less than or equal to 290 kg / m3when the composition of mortar comprises gypsum or the mixture of gypsum and cement as claimed in claim 7.

15. A surface coated with a mortar as claimed in oneof the claims from 10 to 14.

16. The coated surface as claimed in claim 15, wherein the coated surface has a thickness of 50 mm or less .

17. Use of a mortar as claimed in one of the claims from 10 to 14 for coating a surf ace / structure in the civil and industrial building sector .

18. The use as claimed in claim 17 , wherein the surf ace / structure is selected from the group consisting of load-bearing or non-load-bearing masonry or steel structures, ventilation ducts, flues, metal pipes, electrical conduits, plastic ducts, preferably polyvinyl chloride, or metal ducts, preferably copper .

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