WO2010122498A1 - Fire-resistant bituminous composition - Google Patents

Abstract

The present invention relates to novel fire-resistant bituminous compositions including at least one bitumen, at least one phosphoric acid salt, at least one polysaccharide, the amount of phosphoric acid salt and polysaccharide being between 1 and 20 wt % relative to the weight of the bituminous composition, the ratio between the amounts of phosphoric acid salt and of polysaccharide being between 0.2 and 2 wt %, said bituminous composition being free of organic halogen compounds.

Description

 FIRE RESISTANT BITUMINOUS COMPOSITION

TECHNICAL AREA

The present invention is in the field of bitumens. The invention relates to bituminous compositions and in particular bituminous compositions having improved fire resistance. The bituminous compositions according to the invention can be used for road applications and / or industrial applications. PRIOR ART To improve the fire resistance of bituminous compositions, various flame retardant additives have been added to the bituminous compositions.

DE20308971 discloses a bitumen mass comprising intumescent flame retardant additives such as vermiculite, expanded graphite, mixtures of sugar, melamine, ammonium polyphosphate or starch mixtures. The intumescent flame retardant additives are added to the bitumen mass in a proportion of 25 to 55% by weight, preferably 25 to 45%. The amount of flame retardant additives of these bituminous compositions is therefore very important.

In patent application FR2256945, hardly combustible bitumens are described and contain, as flame-retardant components, brominated organic compounds, with a melting point of less than 200 ^° C., phosphorus-containing organic compounds and starch insoluble in cold water. . The brominated compounds are very effective but have the disadvantage of driving during the thermal degradation process the release of toxic and corrosive products such as hydrobromic acid. OBJECTIVES OF THE INVENTION

The aim of the invention is to propose a new bituminous composition, fire-resistant, not comprising halogenated organic derivatives, and comprising at least one bitumen, at least one phosphoric acid salt and at least one polysaccharide, the amount of these two additives being chosen so as to have an improved fire resistance compared to the non-additive bitumen without degrading the physical and mechanical properties of the mixes and / or putties formulated from the additive bituminous composition.

The applicant has discovered that an amount of phosphoric acid salt and polysaccharide of between 1 and 20% by weight, in the bituminous composition, was sufficient to have improved fire resistance. An amount greater than 20% by weight, in the bituminous composition, does not improve the fire resistance of the bituminous composition and furthermore degrades the physical properties and mechanical mixes and / or mastics formulated from the additive bituminous composition.

The main objective of the invention is therefore to formulate a bituminous composition resistant to fire without degrading the physical and mechanical properties of the mixes and / or mastics formulated from the additive bituminous composition.

In particular, the addition of flame retardant additives must not increase too strongly the viscosity of the mixes and / or mastics formulated from the additive bituminous composition according to the invention. In addition, the mastics formulated from the additive bituminous composition according to the invention must maintain satisfactory cold and hot behavior, in particular to comply with UEtac specifications (European Union Specifications for Approval).

Technical in Construction). Mastics formulated from the additive bituminous composition according to the invention must also be sufficiently elastic.

Finally, the mastics formulated from the additive bituminous composition according to the invention must be resistant to aging.

Another object of the invention is to formulate a bituminous mastic in which the flame retardant additives may be substituted in whole or in part for conventionally used fillers, such as mineral fillers. This total or partial substitution must not be to the detriment of the physical and mechanical properties mentioned above. BRIEF DESCRIPTION

The invention relates to a bituminous composition comprising at least one bitumen, at least one phosphoric acid salt, at least one polysaccharide, the amount of phosphoric acid salt and of polysaccharide being between 1 and 20% by weight relative to the mass of the bituminous composition, the ratio between the mass quantities of phosphoric acid salt and of polysaccharide being between 0.2 and 2, said bituminous composition being free of halogenated organic compounds.

Preferably, the phosphoric acid salt is ammonium phosphate or ammonium polyphosphate. Preferably, the ammonium polyphosphate is an ammonium polyphosate having a degree of polymerization greater than 1000.

Preferably, the polysaccharide is chosen from derivatives of starch and / or starch.

Preferably, the polysaccharide is native potato starch or native corn starch.

Preferably, the mass ratio of the amounts of phosphoric acid salt and polysaccharide is 1. Preferably, the bituminous composition further comprises a polymer, preferably from 1 to 20% by weight, relative to the weight of the bituminous composition, preferably from 2 to 15%, more preferably from 5 to 10%.

The invention also relates to a process for preparing a bituminous composition as defined above in which at least one bitumen is heated at a temperature of between 160 ^° C. and 200 ^° C., at least one salt of phosphoric acid, at least one polysaccharide and optionally at least one polymer, the phosphoric acid salt and the polysaccharide being preferably solubilized beforehand in water and dried before being added to the bitumen. The invention also relates to a bituminous mastic comprising a bituminous composition as defined above and fillers.

Preferably, the bituminous mastic comprises from 20 to 90% by weight of bituminous composition, relative to the weight of bituminous mastic, preferably from 30 to 80%, more preferably from 40 to 60%. The invention also relates to a waterproofing membrane comprising a bituminous mastic as defined above.

The invention also relates to an underside of carpet comprising a bituminous mastic as defined above.

The invention also relates to a bituminous mix comprising a bituminous composition as defined above and aggregates.

The invention also relates to the use of 1 to 20% by weight of a mixture of at least one phosphoric acid salt and at least one polysaccharide in bitumen to improve the fire resistance of a composition bituminous mastic, bituminous mastic, waterproofing membrane, underside of carpet or bituminous mix.

The invention also relates to the use of the bituminous composition as defined above to improve the fire resistance of a bituminous mastic, a waterproofing membrane, a carpet bottom or an asphalt bituminous. DETAILED DESCRIPTION The bituminous composition according to the invention comprises at least one phosphoric acid salt.

Phosphoric acid salt is understood to mean salts of phosphoric acid and salts of polyphosphoric acids such as diphosphates (also called pyrophosphates), triphosphates, etc. By way of illustration, mention may be made of phosphates of ammonium, ammonium pyrophosphates, ammonium polyphosphates, melamine phosphates, melamine pyrophosphates, melamine polyphosphates, sodium phosphates, sodium pyrophosphates, sodium polyphosphates. - AT -

Ammonium polyphosphates are preferably used.

Ammonium polyphosphates having a high degree of polymerization are also preferred. Thus for an ammonium polyphosphate of general formula

(NH ₄ POs) _n , ammonium polyphosphates are preferred such that the number n is greater than or equal to 5, preferably greater than or equal to 100, more preferably greater than or equal to 1000.

The ammonium polyphosphate according to the invention comprises from 10 to 60% of phosphorus, preferably from 20 to 50%, more preferably from 30 to 40%.

The ammonium polyphosphate according to the invention comprises from 5 to 30% of nitrogen, preferably from 10 to 25%, more preferably from 15 to 20%.

The bituminous composition according to the invention also comprises at least one polysaccharide.

Polyoside (or polyholoside or polysaccharide) means a polymer consisting of several monosaccharides linked together by O-osidic bonds. The polysaccharides include fructans, glucans such as starches, amylopectins, amyloses, celluloses and glycogens, galactans. The oses are distinguished by their chain length and can be trioses, tetroses, pentoses, hexoses such as glucose, mannose, galactose, fructose, heptoses.

The polysaccharide is preferably starch or starch. Starch (or starch) is a polysaccharide (or polysaccharide) of chemical formula (CeHi ₀ Os) _n , composed of glucose molecules linked by α (1-4) bonds. It can come from seeds (especially cereal seeds such as maize or wheat or legume seeds), roots, tubers and rhizomes such as potatoes, sweet potatoes, cassava, fruits such as banana. Starch or starch from maize, pea and potato is preferably used.

The starch or starch used may be starch or starch native or modified. Modified starch means a native starch or starch which has undergone chemical or physical transformations. The chemical transformations are, for example, operations or reactions of oxidation, dextrinification, fluidification (acid or enzymatic), esterification, etherification and / or crosslinking. The physical transformations are, for example, drum gelatinization operations, extrusion cooking treatments, microwave treatments and ultrasonic treatments. In the context of the invention, starches may be used resulting from one or more chemical transformations and from one or more physical transformations.

The starch or starch according to the invention is preferably chosen from native potato starch, cold-soluble potato starch, cornstarch starch and starch. pregelatinized carboxymethylated potato, native corn starch, high amylose corn starch, pea starch. Potato starch and corn starch, preferably native, are preferred.

The bituminous composition according to the invention comprises from 1 to 20% by weight of a mixture of phosphoric acid salt and of polysaccharide, relative to the weight of bituminous composition, preferably from 2 to 15%, more preferably from at 10%. A greater quantity of additives does not make it possible to increase the fire resistance of the bituminous compositions according to the invention and degrades the physical and mechanical properties of the products formulated from these bituminous compositions.

The ratio between the quantities by weight of phosphoric acid salt and of polysaccharide is between 0.2 and 2, preferably between 0.5 and 1.5, more preferably around 1. A ratio of 1 is preferred because that it allows to obtain an optimal fire resistance. In order to prepare the bituminous composition according to the invention, at least one bitumen is heated to a temperature of between 160 ^° C. and 200 ^° C., and the phosphoric acid salt and the polysaccharide are added, as such, in powder form.

The phosphoric acid salt and the polysaccharide may be added successively or simultaneously, the order of introduction or the manner of introducing them having a priori not much importance.

It is also possible to dilute the phosphoric acid salt in water and add the polysaccharide to inflate it. The water / salt mixture of phosphoric acid / polysaccharide is stirred until a homogeneous dispersion is obtained. The water is then evaporated, for example in a ventilated oven at 80 ^° C., until a dry residue of an intimate mixture of phosphoric acid salt and polysaccharide in which the polysaccharide is impregnated is obtained. of phosphoric acid salt. The dry residue can then be milled to obtain a powder of smaller possible particle size. The dry residue, optionally ground, is then added with stirring to the heated bitumen at a temperature of between 160 ^° C. and 200 ^° C. This method of preparation is preferred and the bituminous composition obtained is more resistant to fire than a bituminous composition in which the phosphoric acid salt and the polysaccharide were not premixed in water.

The bituminous composition comprises at least one bitumen. In the context of the invention, the bitumen may consist of a single type of bitumen or a mixture of bitumens. The bitumens that can be used according to the invention are chosen from bitumens of natural origin, that is to say, those contained in deposits of natural bitumen, natural asphalt or bituminous sands, bitumens derived from petroleum refining. raw materials such as bitumens from atmospheric distillation and / or vacuum oil, these bitumens can be optionally blown, vis-reduced and / or deasphalted. The bitumens used may also be fluxed bitumens by addition of volatile solvents, petroleum fluxes, carbo-chemical fluxes and / or fluxes of vegetable origin. It is also possible to use synthetic bitumens that are free of asphaltenes, also called clear, pigmentable or colorable bitumens.

The bitumen according to the invention is chosen from bitumens which have a penetrability according to EN 1426 of between 5 and 500 1/10 mm. The penetrability of the bitumen will be chosen according to the intended application. Thus for asphalt paving formulation, the bitumen has a penetrability of between 5 and 500 1/10 mm, preferably between 10 and 80, more preferably between 20 and 60, even more preferably between 35 and 50. For external coatings , in particular the waterproofing membranes, the bitumen has a penetrability of between 140 and 220, preferably between 160 and 200. For interior linings, in particular carpet tiles (or under carpets), the bitumen has a penetrability between 10 and 50.

The bituminous composition according to the invention preferably comprises from 60 to 99% by weight of bitumen, relative to the weight of the bituminous composition, preferably from 70 to 95%, more preferably from 75 to 90%. The bituminous composition according to the invention may also comprise at least one polymer. The polymers that can be used according to the invention are elastomers or plastomers, preferably elastomers. For example, thermoplastic elastomers such as styrene and butadiene random or block copolymers, linear or star (SBR, SBS) or styrene and isoprene (SIS), copolymers, may be mentioned in an indicative and nonlimiting manner. of ethylene and vinyl acetate, copolymers of ethylene and methyl acrylate, copolymers of ethylene and butyl acrylate, copolymers of ethylene and maleic anhydride, copolymers of ethylene and glycidyl methacrylate, copolymers of ethylene and glycidyl acrylate, copolymers of ethylene and propene, ethylene / propene / diene terpolymers (EPDM), acrylonitrile / butadiene / styrene terpolymers (ABS), ethylene / acrylate or alkyl methacrylate / acrylate or glycidyl methacrylate terpolymers and in particular ethylene / methyl acrylate / glycidyl methacrylate terpolymers and ethylene / acrylate or methacrylate terpolymers of alkyl / maleic anhydride and in particular ethylene / butyl acrylate / maleic anhydride terpolymer, olefinic homopolymers and copolymers of ethylene (or propylene or butylene), polyisobutylenes, polybutadienes, polyisoprenes, polyvinyl chloride rubber crumbs, butyl rubbers, polyacrylates, polymetacrylates, polychloroprenes, polynorbornenes, polybutenes, polyisobutenes, polyethylenes or any polymer used for the modification of bitumens, and mixtures thereof.

The preferred polymers are copolymers based on styrene units and butadiene units.

The bituminous composition according to the invention preferably comprises from 1 to 20% by weight of polymer, relative to the bituminous composition, preferably from 2 to 15%, more preferably from 5 to 10%.

The polymer can be crosslinked with crosslinking agents. The crosslinking agents that can be used are of a very varied nature and are chosen as a function of the type (s) of polymer (s) contained in the bituminous composition according to the invention. Preferably, the crosslinking agent is selected from sulfur alone or in admixture with vulcanization accelerators. These vulcanization accelerators are either hydrocarbyl polysulfides, sulfur-donor vulcanization accelerators, or non-sulfur donor vulcanization accelerators. The hydrocarbyl polysulfides may be chosen from those defined in the patent FR2528439. The sulfur-donor vulcanization accelerators may be chosen from thiuram polysulfides, for example, tetrabutylthiuram disulfides, tetraethylthiuram disulfides and tetramethylthiuram disulfides. The non-sulfur-donor vulcanization accelerators that may be used according to the invention may be sulfur-containing compounds chosen in particular from mercaptobenzothiazole and its derivatives, dithiocarbamates and its derivatives, and thiuram monosulfides and its derivatives. For example, zinc-2-mercaptobenzothiazole, zinc dibutyldithiocarbamate and tetramethylthiuram monosulphide may be mentioned. For more details on the sulfur-donor and non-sulfur-donor vulcanization accelerators that can be used according to the invention, reference can be made to patents EP0360656, EP0409683 and FR2528439. Preferably, the bituminous composition according to the invention comprises from 0.1 to 2% by weight of crosslinking agent, relative to the weight of the bituminous composition. The invention also relates to a bituminous mix comprising the bituminous composition described above and aggregates, optionally fillers. The aggregates are inorganic and / or synthetic aggregates, in particular recycling costs, of dimensions greater than 2 mm, preferably of between 2 mm and 14 mm. The mineral fillers consist of fines (particles less than 0.063 mm in size), possibly sand (particles with dimensions of between 0.063 mm and 2 mm) and possibly chippings (particles greater than 2 mm in size, preferably between 2 mm and 4 mm). The bituminous mix according to the invention comprises from 1 to 10% by weight of bituminous composition as defined above, relative to the total weight of the bituminous mix, preferably from 4 to 8% by weight, the rest consisting of aggregates (which may include fillers). The mix according to the invention may be used in road application for the manufacture of roads, as sub-base layers, base layers, base layers, surface layers such as the tie layers and / or the wearing courses. The mix according to the invention having improved fire resistance, may be used in tunnels. In case of fire, the mix according to the invention will allow a less spread of fire and reduced emissions of fumes.

The invention also relates to a bituminous mastic comprising the bituminous composition described above and fillers. The bituminous mastic may be used as internal or external coatings used for sealing, vibration damping, thermal insulation and / or sound insulation. Such coatings are particularly used in the building (exterior / interior), in automobile bodies or in cold-production machines (refrigerators, freezers, air conditioners, etc.). Among the interior claddings of buildings, there may be mentioned floor coverings such as under carpets or wall coverings. Among the exterior claddings of buildings, there may be mentioned waterproofing membranes (or screeds) for roofs, terraces, facades, walls.

The filler is generally selected from mineral fillers such as chalk (or calcium carbonate). The filler may also be constituted (at least in part) by fibrous fillers, which are advantageously chosen from the group comprising mineral fibers, preferably glass fibers, carbon fibers, synthetic fibers, preferably polyester fibers. polyesters, polyolefins or polyamides, and mixtures thereof.

Typically, a bituminous mastic comprises from 15 to 85% by weight of fillers, such as chalk, relative to the weight of bituminous mastic, preferably from 25 to 65%, more preferably from 35 to 55%, even more preferably from 40 to 65% by weight. at 50%.

The bituminous mastic according to the invention comprises less fillers such as chalk since it comprises a mixture of phosphoric acid salt and polysaccharide which can act as flame retardants and fillers. Preferably, the bituminous mastic according to the invention comprises from 5 to 75% of mineral fillers such as chalk, preferably from 15 to 55%, more preferably from 25 to 45%, even more preferably from 30 to 40%. Preferably, the bituminous mastic comprises from 20 to 90% by weight of bituminous composition according to the invention, relative to the weight of bituminous mastic, preferably from 30 to 80%, more preferably from 40 to 60%.

Preferably, the bituminous mastic comprises from 1 to 20% by weight of polymer, relative to the weight of bituminous mastic, preferably from 5 to 10%.

Typically a bituminous mastic for a waterproofing membrane according to the invention comprises:

50 to 60% of bitumen, 1 to 15% of phosphoric acid salt and of polysaccharide, 5 to 10% of polymer, 5 to 20% of filler, bitumen, phosphoric acid salt the polysaccharide, the polymer and the filler being as defined above.

Typically a bituminous mastic for a carpet underlay according to the invention comprises: - from 15 to 25% of bitumen, from 1 to 15% of phosphoric acid salt and of polysaccharide, from 1 to 5% of polymer, from 50 to 70% filler, the bitumen, the phosphoric acid salt, the polysaccharide, the polymer and the filler being as defined above. EXAMPLES

The products used are as follows: a bitumen of penetrability, according to EN 1426, equal to 190 1/10 mm, of the ammonium polyphosphate of general formula (NH ₄ POs) _n with n greater than 1000, - different polysaccharides such as native potato starch, cold-soluble potato starch, pregelatinized carboxymethyl potato starch, native corn starch, amylose-rich corn starch and pea starch, a plugged block polymer based on styrene and butadiene units having a styrene content of 30% by weight, and as a filler, chalk.

Various control bituminous compositions (Ti to T ₄ ) and according to the invention (Ci) are prepared. The bituminous compositions have the compositions (% by weight) given in Table I, below: Table I

The bituminous compositions are prepared in the following manner: In a stirred reactor at 180 ^° C., the bitumen, the ammonium polyphosphate and native potato starch are mixed. The mixture is mixed for about 2 hours at about 180 ^° C. The ammonium polyphosphate and the native potato starch are suspended in the bitumen.

The fire resistance of the bituminous compositions according to the invention is evaluated by thermogravimetric analysis (TGA). It is known in fact that the fire performance of a compound is correlated with its thermal stability. The tests are carried out under air using a microbalance under the following conditions: heating rate: 10 ° C / min, mass of the sample: 10 mg, temperature: 20 ^° C. - 800 ^° C. then trace for each composition, an interaction curve of the various constituents of a composition as a function of temperature. This curve represents, at different temperatures, the difference between the experimental residual mass (in%) of the composition under consideration and the theoretical residual mass (in%) of the various constituents of the composition weighted by their concentration. The difference of the residual masses Δ (M (T)) is calculated as follows:

A (M (T)) = M _exp (T) - Mthéo (T) with: M _exp (T): experimental residual mass of the composition as a function of the temperature T,

Mthéo (T): theoretical residual mass of the composition as a function of temperature T, calculated by linear combination of experimental residual masses of bitumen and additives as a function of temperature T and weighted by their concentrations, as follows:

M _the0 (T) = (1 - x) * Mb ₁₄ (T) + x * M _add (T) with: x the additive content,

Mbit (T): experimental residual mass of bitumen as a function of temperature T, M _a dd (T) experimental residual mass of additives as a function of temperature T. The interaction curves make it possible to observe a possible increase (positive values) or decrease (negative values) of the thermal stability and therefore of the fire resistance, related to the presence of the additives in the bitumen (see Figure I).

It is found under air, a stabilizing effect of the mixture of ammonium polyphosphate and native potato starch on the bitumen, and over the entire temperature range, from 50 ⁰ C and up to 800 ⁰ C, the stabilizing effect is really important around 600 ^° C. In particular potato starch has a stabilizing effect on the bitumen between 50 ⁰ C and 700 ⁰ C and the ammonium polyphosphate has a stabilizing effect on the bitumen between 300 ^° C. and 800 ^° C. A concentration of 30% by weight of a mixture of ammonium polyphosphate and native apple starch in the bituminous composition does not give better results than a concentration of 20% by weight, the interaction curves of the compositions T ₄ and Ci being almost superimposed.

The various polysaccharides such as cold-soluble potato starch, pregelatinized carboxymethyl potato starch, native corn starch, high amylose corn starch and pea starch are as effective as native potato starch and give similar results.

Fire tests are also carried out on the various bituminous compositions. For this, samples of bituminous compositions approximately 1 cm ² and 2 mm thick are deposited on a metal plate, then subjected to the hottest part of a Bunsen burner (temperature above 800 ^° C.) for 10 seconds. . The observations are as follows: for the bituminous control composition T ₁ , a fluidification of the bitumen is observed, - for the bituminous composition according to the invention C ₁ , the formation of a foam which is viscosified is observed and forms a protective layer with an alveolate characteristic of intumescence which avoids the spread of fire. Various bituminous mastics are then prepared from the bituminous compositions above. The bituminous mastics have the compositions (% by weight) given in Table II, below:

Table II

Les mastics bitumineux sont préparés de la manière suivante : Dans un réacteur sous agitation à 180⁰C, on mélange le bitume et le polyphosphate d'ammonium et la fécule de pomme native avec le polymère à base de styrène et de butadiène. On mélange pendant environ 2h à environ 180⁰C. On introduit ensuite dans le mélange obtenu, la craie. On mélange pendant environ 30 mn à l80°C.

The bituminous mastics are prepared in the following manner: In a stirred reactor at 180 ^° C., the bitumen and the ammonium polyphosphate and the native apple starch are mixed with the styrene-butadiene-based polymer. It is mixed for about 2 hours at about 180 ^° C. The chalk is then introduced into the mixture obtained. Mix for about 30 minutes at 180 ° C.

The properties of bituminous mastics are given in Table III:

Table III

(*) NM: Not measurable.

(1) Penetration at 25 ° C according to EN 1426. (2) Penetration at 50 ^° C. according to EN 1426. (3) Ring-ball softening temperature according to EN 1427. (4) Cold bendability according to the standard NF EN 495-5. (5) Retention according to standard NF ISO 2289. (6) Traction according to the standard EN 13587. (?) PAV (Pressure Aging Vessel) according to standard NF EN 14769, accelerated aging test carried out in autoclave at 100 ⁰ C under an air pressure of 21 bar for 44 hours.

(8) Specifications of the European Union for Technical Approval in Construction. The MTi control bituminous mastic is the reference sealant, it does not include flame retardant additives. Bitumen additive with flame retardant additives provides improved fire resistance, but should not be at the expense of other properties of the sealant. It is sought to obtain properties as close as possible to the MTi control which has properties in accordance with UEAtc specifications. It can be seen that: the viscosity at 180 ^° C. of the control putty MT ₄ is not measurable. MT ₄ control putty is much more viscous than MCi and MTi sealants. This is due to too much ammonium polyphosphate and native potato starch in the MT ₄ control putty. the penetrability at 25 ⁰ C and 50 ⁰ C of the three mastics is similar and the ball and ring temperature of the three mastics is similar, the consistency of the three mastics is therefore similar and the hot behavior of the three mastics is therefore similar. the cold crease temperature of the MT ₄ sealant is out of specification. The mastics MTi and MCi do not crack up to -24 ° C and -22 ° C, respectively, whereas the mastic MT ₄ starts to crack from -19 ° C. The cold behavior of the mastic MT ₄ is really degraded while the cold behavior of mastic MCi is comparable to that of mastic MTi. the elastic behavior of the three mastics is similar according to the stains of remanence and traction. MT ₄ sealant is much more sensitive to aging than MTi or MCi sealants. There are large variations in penetrability and cold pliability. The MT ₄ sealant has hardened immensely after this aging test and its cold pliability temperature has become positive. The MT ₄ putty, after a few years of use, will therefore have properties that are much more degraded than the MTi and MCi sealants. The amount of phosphoric acid salt and polysaccharide in the bituminous composition must therefore be less than 20% by weight. This amount improves the fire resistance of the bituminous composition while maintaining the other properties intact.

Claims

A bituminous composition comprising at least one bitumen, at least one phosphoric acid salt, at least one polysaccharide, the amount of phosphoric acid salt and of polysaccharide being between 1 and 20% by weight relative to the mass of the bituminous composition, the ratio between the mass quantities of phosphoric acid salt and polysaccharide being between 0.2 and 2, said bituminous composition being free from halogenated organic compounds. The bituminous composition of claim 1 wherein the phosphoric acid salt is ammonium phosphate or ammonium polyphosphate. The bituminous composition of claim 2 wherein the ammonium polyphosphate is an ammonium polyphosate having a degree of polymerization greater than 1000. 4. Bituminous composition according to any one of claims 1 to Wherein the polysaccharide is selected from starch and / or starch derivatives. Bituminous composition according to any one of claims 1 to Wherein the polysaccharide is native potato starch or native corn starch. 6. Bituminous composition according to any one of claims 1 to Wherein the mass ratio of phosphoric acid salt and polysaccharide amounts to 1. 7. bituminous composition according to any one of claims 1 to 6 further comprising a polymer, preferably 1 to 20% by weight, relative to the weight of the bituminous composition, preferably from 2 to 15%, more preferably from 5 to 10%. 8. Process for the preparation of a bituminous composition according to any one of claims 1 to 7 wherein at least one bitumen is heated to a temperature between 160 ⁰ C and 200 ⁰ C, is added at least one salt of phosphoric acid, at least one polysaccharide and optionally at least one polymer, the phosphoric acid salt and the polysaccharide being preferably solubilized beforehand in water and dried before being added to the bitumen. 9. A bituminous mastic comprising a bituminous composition according to any one of claims 1 to 7 and fillers. 10. A bituminous mastic according to claim 9 comprising from 20 to 90% by weight of bituminous composition, relative to the weight of bituminous mastic, preferably from 30 to 80%, more preferably from 40 to 60%. 11. A waterproofing membrane comprising a bituminous mastic according to any one of claims 9 to 10. Carpet floor comprising a bituminous mastic according to any one of claims 9 to 10. 13. bituminous mix comprising a bituminous composition according to any one of claims 1 to 7 and aggregates. 14. Use of 1 to 20% by weight of a mixture of at least one phosphoric acid salt and at least one polysaccharide in bitumen to improve the fire resistance of a bituminous composition, a bituminous mastic, waterproofing membrane, underlay carpet or bituminous mix. 15. Use of the bituminous composition according to any one of claims 1 to 7 for improving the fire resistance of an asphalt mastic, a waterproofing membrane, a carpet bottom or a bituminous mix. .