Waterproofing chipless asphalt top seal composition Field of the invention The present invention relates to waterproofing chipless asphalt top seal compositions. The compositions provide a less rough surface, less bitumen contamination and less loose aggregate material after their application. The compositions can be employed under unfavourable environmental conditions such as high humidity and low temperature.

Background of the invention

Sealing of asphalt roads is important as this treatment will prolong the service life of the road. Various sealing techniques are available and surface dressing, slurry sealing and micro-surfacing are commonly used techniques for maintenance of asphalt roads.

Surface dressing of asphalt pavements is one of the most cost-effective solutions for road maintenance as material costs are low and the rate of application is relatively high. A thin layer of a surface dressing, e.g. a bitumen emulsion, a cutback bitumen or a vegetable oil modified bitumen, is applied onto a clean asphalt base layer by bitumen tankers equipped with a spray bar. Subsequently, aggregate material is applied and upon drying the chips adhere to and are embedded in the bituminous layer.

After compaction of the aggregate material, the road is reopened for traffic and the aggregate material will be embedded further into the bituminous layer as well as into the asphalt base layer. Due to the presence of loose aggregate material, traffic speed needs to be limited for a certain period of time, despite that the road is swept once or twice per month after the surface dressing and the aggregate material have been applied. Although this maintenance technology is fairly efficient and economical, surface dressing can create a nuisance to the public.

For example, speed restrictions are a nuisance to the public. Moreover, loose aggregate material is unpleasant to drive and the initial anti-skid performance of an un- swept road is not sufficient. The rough texture of a surface dressing can be noticed by the high level of noise and vibrations in the car and e.g. for skaters and cyclists the rough texture is for the same reason even a greater nuisance. Furthermore, on such surfaces, traffic generates noise at an unpleasant level for the public. Further disadvantages include bleeding of bitumen due to overspray giving rise to the formation of bitumen spots, wheel tracks due to local embedding of the aggregate material, formation of aggregate material partially coated soft bitumen which may stick to shoes and tires and which, especially in urban areas, can be dragged into the houses creating all kind of damages. Additionally, people, for instances playing children, may fall on these rough surfaces and may easily be wounded. For these reasons, surface dressing has become less popular in e.g. the Netherlands and especially in urban areas and other densely populated regions, so that the area of asphalt roads maintained in this manner is relatively small. But also in other highly developed countries like Japan, the volumes of surface dressing is small compared to other maintenance techniques. Asphalt overlays or thin asphalt overlays have therefore become very popular despite the less favourable economics of these systems.

In view of the above, there is a strong need for a maintenance technique which has more or less the same economics as surface dressing but which creates a less rough surface and which does not have the disadvantages associated surface dressing.

Low penetration grade bitumen (also known as hard bitumen) is very difficult to emulsify as is well known in the art. The harder the bitumen, the lower the needle penetration value and the higher the softening point, but also the more difficult it becomes to emulsify the bitumen into storage stable, fast breaking bituminous emulsions. Low storage stability is reflected in a fast rate of separation of an aqueous upper phase and a bitumen-rich lower phase when a bituminous emulsion is stored at room temperature under quiescent conditions. The difference in water content between the phases formed is the value for the so-called storage stability, which is determined according to standard method NEN-EN 12847. Hence, the lower this value, the better the storage stability is and a value of zero indicates perfect storage stability. The storage stability is often expressed in a percentage and to obtain such percentages, the values must be multiplied by 100%.

Slow breaking of a bituminous emulsion is reflected in a long period of time before a solid film is formed after application of the emulsion to the road surface. It is well accepted in the art that the breaking index, or sometimes also called filler index, is a good measure for the time to break the bituminous emulsion after application to a road surface. A high breaking index implies slow breaking. The breaking index is usually determined according to standard method NEN-EN 13075-1.

Storage stability can be improved by including more emulsifier in the bituminous emulsion. However, although improved storage stability is achieved, the breaking index also increases significantly which is obviously not desired.

A further advantage of bituminous emulsions having a low breaking index is that these emulsions will also break relatively quickly under humid and cold conditions allowing the product to be used under less favourable environmental conditions.

US 5.246.986 of Elf France, incorporated by reference herein, discloses an emulsion of a bituminous binder wherein a thickening agent is employed that contains at least 40% by weight of scleroglucan, wherein it is preferred that the aqueous phase of the emulsion comprises 100 to 5000 ppm, preferably 200 to 2000 ppm of scleroglucan. Examples 2 and 4 discloses cationic emulsions comprising bitumen having a penetration of 180 - 220 10 ^"1 mm and scleroglucan of a technical grade (which consists of 70 wt.% of scleroglucan and 30 wt.% of biomass), wherein the scleroglucan (calculated on actual scleroglucan content) is 0.021 wt.%. The penetration was determined according to NF Standard T 66004 which is equivalent to ASTM D5- 97 (cf. C. Garrigues and P. Vincent, "Sulfur/Asfalt binders for Road Construction", "New uses of Sulfur", Chapter 8, pages 130 - 153, 1975; DOI 10.1021/ba-1975- 0140.ch008, Advances in Chemistry, Vol. 140, ISBN13: 9780841202184, elSBN: 9780841223219). US 5.246.986 does not disclose waterproofing chipless asphalt top seal compositions comprising particulate material.

US 5.750.598 of Elf France, incorporated by reference, discloses vulcanizable bitumen/polymer compositions comprising bitumen, an elastomer that can be vulcanized, a sulfur-donating vulcanization agent, a vulcanization accelerator and a viscosity-reducing agent. These compositions can be used for manufacturing emulsions which optionally comprise a viscosity-controlling additive, e.g. a water soluble polyurethane or a gum such as xanthan or scleroglucan.

GB A 2452903 of Colas S.A., incorporated by reference, discloses an emulsion comprising an aqueous phase and an organic phase comprising a binder composition, wherein the binder composition comprises bitumen and a non-aromatic polymer, in particular polyisoprene. The emulsion is preferably cationic. The bitumen has preferably a penetration of 50 to 150 10 ^"1 mm. The emulsion is rapidly breaking as indicated by a breaking index (according to NFT 66-017 (tentative French National Standard December 1983) of 45 - 100. The emulsion preferably comprises 45 - 75 wt.% of the binder composition, based on the total weight of the emulsion.

WO 2009/1 13854 of Latexfalt B.V., incorporated by reference herein, discloses emulsions comprising a (1— >3)-P-D-glucan, preferably scleroglucan, a biodegradable emulsifier which may be non-ionic or cationic, and bitumen. The bitumen have a penetration in the range of about 10 to about 350 10 ^"1 mm according to ASTM D5-97, more preferably about 70 to about 220 10 ^"1 mm.

As explained above, there is a need in the art for bituminous emulsions having excellent storage stability which are fast breaking. In particular, there is a need in the art for such bituminous emulsions which incorporate low penetration bitumen (also known as hard bitumen). There is also a need in the art for a maintenance technique which has more or less the same economics as surface dressing but which does not have the disadvantages associated surface dressing.

Summary of the invention

The present invention relates to waterproofing chipless asphalt top seal composition comprising (a) a particulate material, wherein the average diameter of the particulate material is 3 mm or less, preferably less than 2 mm, and (b) an emulsion comprising a (1— »3)-P-D-glucan, a cationic emulsifier, and a bituminous binder having a penetration of less than 70 10 ^"1 mm according to ASTM D5-97.

The average diameter of the particulate material according to British standard BS 63. However, according to the current European standard NEN-EN 13043, two dimensions are used to characterize the size of particulate material (d/D; NEN-EN 13043). A size of 3 mm according to BS 63 is equal to a d/D of 1/4 (cf. Shell Bitumen Handbook, 5 ^th Ed., page 224, Table 11.2, 2003).

The present invention further relates to a process for chip sealing a road surface, wherein a composition according to the present invention is applied to said road surface.

The present invention also relates to a process for chip sealing a road surface, wherein an emulsion is applied to said road surface followed by embedding a finely graded aggregate material, wherein said emulsion comprises a (1— >3)-P-D-glucan, a cationic emulsifier, and a bituminous binder having a penetration of less than 70 10 ^"1 mm according to ASTM D5-97, and wherein the average diameter of the finely graded aggregate material is 3 mm or less, preferably less than 2 mm.

The present invention additionally relates to the use of an emulsion comprising a (1— »3)-P-D-glucan, a cationic emulsifier, and a bituminous binder having a penetration of less than 70 10 ^"1 mm according to ASTM D5-97 for applying a waterproofing top seal layer to an asphalt layer.

Detailed description of the invention

The verb "to comprise" as is used in this description and in the claims and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there is one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one".

The term "emulsion" is to be understood as a system in which liquid droplets and/or liquid crystals are dispersed in a liquid. In emulsions the droplets often exceed the usual limits for colloids in size. An emulsion is denoted by the symbol O/W if the continuous phase is an aqueous solution and by W/O if the continuous phase is an organic liquid (an "oil"). More complicated emulsions such as 0/W/O (i.e. oil droplets contained within aqueous droplets dispersed in a continuous oil phase or three-phase emulsions) are also included by the term "emulsion". Photographic emulsions, although colloidal systems, are not emulsions in the sense of the term "emulsions" as used in this document (cf. International Union of Pure and Applied Chemistry, Manual of Symbols and Terminology for Physiochemical Quantities and Units, Appendix II, Definitions, Terminology, and Symbols in Colloid and Surface Chemistry, Part 1, web version 2001). The type of emulsion (O/W or W/O) is determined by the volume ratio of the two liquids. For example, with 5% water and 95% oil (an O/W phase ratio of 19), the emulsion is usually W/O.

In this document, "hard" bitumen is to be understood as a bitumen having a penetration of about 10 to about 100 10 ^"1 mm according to ASTM D5-97. On the other hand, "soft" bitumen is to be understood as having a penetration of about more than about 100 to about 350 10 ^"1 mm according to ASTM D5-97. As is well known in the art, the unit for penetration according to ASTM D5-97 is "10 ^"1 mm". The (l→3)-P-D-glucan

As is known in the art, (1— »3)-P-D-glucans may have different types of linkages. According to the invention, it is preferred that the (1— »3)-P-D-glucan has also (1—6)- β-D-linkages. It is also preferred that the polymer has glucopyranose side chains.

According to the present invention, it is preferred that the (1— »3)-P-D-glucan is a non-modified (1— >3)-P-D-glucan.

According to the invention, the glucan is selected from the group consisting of scleroglucan (CAS No. 39464-87-4), schizophyllan (CAS No. 9050-67-3), laminaran (CAS No. 9008-22-4), cinerean, lentinan (CAS No. 37339-90-5) and curdlan (CAS No. 54724-00-4). However, curdlan is less preferred because of its low water solubility at acidic pH. Most preferably, the glucan is scleroglucan.

Suitably, the glucan is used in an admixture with an oil, preferably vegetable oil, more preferably a food grade vegetable oil, to protect glucan particles to conglomerate when they are contacted with an aqueous medium.

The cationic emulsifier

Cationic emulsifiers are well known in the art. Preferred emulsifiers are selected from the group consisting of quaternary amines, quaternary amino-amines and quaternary imidazolines. Quaternary amines include products such as diquaternary amines, e.g. the Redicote® products manufactured by AkzoNobel. A particularly preferred group of such cationic emulsifiers are derived from amines having the formula: R-NH-(C _m H2 _m -NH)p-(C„H2 _n )-NH ₂ wherein R is a C ₁ -C30 aliphatic group, m is an integer in the range from 1 to 8, p in an integer in the range of 0 to 6, and n is an integer in the range of 1 - 8. Another particularly preferred group of such cationic emulsifiers are derived from amidoamines having the formula:

R-C(0)NH-(C _m H2 _m -NH) _p -(C„H2 _n )-NH ₂ wherein R is a C1 -C30 aliphatic group, m is an integer in the range from 1 to 8, p is an integer in the range of 0 to 6, and n is an integer in the range of 1 - 8.

Imidazoline emulsifiers may for example be obtained by heating amidoamines as is for example disclosed in US 5.352.285, incorporated by reference.

Yet another particularly preferred group of cationic emulsifiers are biodegradable emulsifiers. These biodegradable emulsifiers are preferably selected from the group consisting of alkylpolyglycosides according to formula (I), betaine glycines according to formula (II) and choline esters according to formula (III). These biodegradable emulsifying agents are disclosed in more detail below.

US 6. 1 17.934, incorporated by reference herein, discloses the non-ionic emulsifying agents of the group of alkylpolyglycosides of formula (I):

R'0(R ² 0)b(Z). (I) wherein R ¹ is an alkyl group having 5 to 24 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms and Z is a saccharide group having 5 or 6 carbon atoms, b is an integer having a value of 0 to 12 and a is an integer having a value of 1 to 6. Preferably, b is 0 and Z is a glucose residue. The alkyl group is preferably linear and may optionally contain up to three carbon-carbon double bonds. As is disclosed in US 6.117.934, the number of saccharide groups, i.e. a, is a statistical mean value.

Betaine has the formula Me ₃ N ⁽⁺⁾ -CH ₂ -COO ^w . In the art quaternary N ⁽⁺⁾ -(CH ₂ ) _n - compounds (i.e. combinations of a cationic group and an anion group at close distance from each other within one molecule are generally called "betaines", wherein is an anion, e.g. a halide, a sulfonate or a phosphonate. However, since N- quaternised glycine (H ₂ N-CH ₂ -COOH) is betaine, compounds having the formula Me ₃ N -CH2-COOR are in this document indicated as "betaine esters" or "betaine ester derivatives", despite the fact that they lack an anionic group.

Choline has the formula and the esters thereof are in this document indicated as "choline esters" or "choline ester derivatives".

US 2007/0243321, incorporated by reference herein, discloses cationic emulsifying agents of the group of betaine esters of formula (II):

X ^~ (R ³ ) ₃ N ⁺ -C(R ⁴ ) ₂ -C(0)-Z-R ⁵ (II) wherein X is a sulphonate group, R ³ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁴ is either hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms, Z is either O or NH, and R ⁵ is a group having the formula C _n H ₂ (2n - m)+i , wherein m denotes the number of carbon carbon double bonds, with 6≤ n≤ 12 and 0≤ m≤ 3. If the alkyl group comprises 3 - 6 carbon atoms, it may also have a cyclic structure and may include one to two heteroatoms selected from the group of nitrogen and oxygen.

Other betaine esters of formula (II) include (not disclosed in US 2007/0243321) those compounds wherein X is an anion other than a methane sulphonate, a paratoluene sulphonate or a camphor sulphonate anion, e.g. a halide, preferably chloride.

US 2005/0038116, incorporated by reference herein, discloses CH ₃ -(CH ₂ )i7- C(0)-0-(CH ₂ )2- ⁺ N(CH ₃ ) ₃ Cr (stearoyl choline chloride) and its use for the treatment of certain diseases. This compound can also be used as an emulsifier according to the present invention.

WO 2006/066643, incorporated by reference herein, discloses esters of choline and fatty acids and cosmetic products comprising such esters. The esters are said to have bactericide activity and have the formula R-C(0)-0-(CH2)2- ⁺ N(CH ₃ ) ₃ X ^" , wherein R C ₆ - C ₃ 6 alkyl group and X ^" is a halogenide, nitrate, phosphate, tosylate or methanesulphonate. Also these esters can be used as an emulsifier according to the present invention. Another group of cationic emulsifiers are the group of choline ester derivatives of formula (III):

X ^" (R ³ ) ₃ N ⁺ -[C(R ⁴ ) ₂ ] _p -Z-C(0)-R ⁵

(III) wherein X ^" is a counter ion, e.g. a sulphonate group or a halide, R ³ is a linear or branched alkyl group having 1 to 6 carbon atoms, p is 1 or 2 (preferably 2), R ⁴ is either hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms, Z is either O or NH, and R ⁵ is a group having the formula C _n H _2(2n _ _m )+i , wherein m denotes the number of carbon carbon double bonds, with 6≤ n≤ 12 and 0≤ m≤ 3, or a group having the formula C _n H _2n+1 , wherein 1 ≤ n≤ 24. If the alkyl group comprises 3 - 6 carbon atoms, it may also have a cyclic structure and may include one to two heteroatoms selected from the group of nitrogen and oxygen. When X- is a sulphonate, it is preferred that X- is a Ci - C ₁₂ monoalkyl sulphonate, wherein the alkyl group may be linear or branched and/or may optionally be interrupted by one or more hetero-atoms selected from O and N. If X ^" is a halide, it can in principle be F ^" , CI ^" , Br ^" or Γ. However, it is preferred that X ^" is CI ^" .

The bituminous binder

The bitumen employed in the emulsions of the present invention may either be straight run products or processed products (cf. Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., Vol. 3, pages 689 - 724).

According to the present invention, the bituminous binder has a penetration of less than 70 10 ^"1 mm according to ASTM D5-97, preferably less than 65 10 ^"1 mm, more preferably less than 60 10 ^"1 mm and most preferably 55 10 ^"1 mm or less. It is furthermore preferred that the bituminous binder has a penetration of more than 10 ^"1 mm, more preferably 15 10 ^"1 mm or more and most preferably 20 10 ^"1 mm or more. Well known penetration grades include 20/30, 35/50 and 40/60.

According to the present invention, the bituminous binder may comprise a blend of bituminous binders having different penetration grades, provided that the blend has a penetration of less than 70 10 ^"1 mm according to ASTM D5-97. According to a preferred embodiment, the bituminous binder comprises a blend of a soft bitumen, i.e. a soft bitumen having a penetration of more than about 100 10 ^"1 mm according to ASTM D5-97, preferably more than about 100 or about 350 10 ^"1 mm, more preferably of more than about 100 to about 220 10 ^"1 mm, even more preferably about 160 to about 220 10 ^"1 mm, and a hard bitumen, i.e. a hard bitumen having a penetration of about 100 10 ^"1 mm or less according to ASTM D5-97, preferably about 100 or less to about 10 10 ^"1 mm, more preferably of about 60 to about 10 10 ^"1 mm, even more preferably about 50 to about 20 10 ^"1 mm, The blend preferably comprises a weight ratio of a soft bitumen to a hard bitumen in the range of 1 to 30, more preferably in the range of 1 to 10

According to an embodiment the present invention, it is preferred that the bituminous binder is selected from the group consisting of paraffinic and naphtenic bitumen. Further components

The emulsions according to the present application further preferably comprise an elastomer and/or a petroleum resin and/or a natural resin. The addition of an elastomer and/or a petroleum resin and/or a natural resin has the advantage that life of the road surface coated with the emulsion according to the present invention is enhanced. Elastomers, petroleum resins and natural resins are also beneficial for the flexibility of the coated road surface. The addition of an elastomer and/or a petroleum resin and/or a natural resin further reduces the temperature dependence of visco-elastic properties.

According to the present invention, the elastomer is preferably selected from the group consisting of ethylene-vinyl acetate copolymers, polybutadienes, polyisoprenes, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, styrene- ethylene-butadiene-styrene copolymers, styrene-propylene-butadiene-styrene copolymers, butadiene-styrene diblock copolymers, styrene-butadiene styrene triblock copolymers, isoprene-styrene diblock copolymers, styrene-isoprene-styrene triblock copolymers, wherein the diblock or triblock copolymers may occur in morphological shapes as star-shaped polymers wherein a cross-linking agent such as divinyl benzene is employed in the manufacturing process. However, according to the present invention, it is preferred that the elastomer is a polymer comprising two adjacent, optionally substituted butadiene units such as isoprene, most preferably a polybutadiene, a polyisoprene, a styrene-ethylene-butadiene-styrene copolymer, a styrene-propylene-butadiene-styrene copo lymer, a butadiene-styrene diblock copolymer, a styrene-butadiene-styrene triblock terpolymer, a isoprene-styrene diblock copolymer or a styrene-isoprene-styrene triblock terpolymer. More preferably, the elastomer is a polybutadiene, a polyisoprene, a styrene-ethylene-butadiene-styrene copolymer, a styrene-propylene-butadiene-styrene copolymer or a styrene-butadiene- styrene triblock terpolymer. According to another preferred embodiment of the present invention, the elastomer is an ethylene-vinyl acetate copolymer.

The petroleum resin is preferably selected from the group consisting of resins manufactured by polymerisation of unsaturated hydrocarbons present in unsaturated petroleum fractions, coumarone-indene resins, hydrogenated petroleum resins, modified petroleum resins, cyclopentadiene-based resins, thermoplastics, or a mixture thereof. Most preferably, the petroleum resin is a C5 - C9 petroleum resin, a C9 - petroleum resin, a C5 - petroleum resin or a mixture thereof.

The natural resin is preferably selected from the group of rosin resins and terpene resins.

The particulate material

According to the present invention, the particulate material can be selected from the group consisting of aggregate material (e.g. chippings), rubber crumbs, fibres of e.g. vegetable origin, wood chips, waste biomass such as Empty Fruit Bunch, and mixtures thereof.

The emulsion

According to the present invention, the emulsion comprises about 25 to about 75 wt.% of an aqueous phase and about 75 to about 25 wt.% of an oil phase, based on the total weight of the emulsion. More preferably, the emulsion comprises about 30 to about 70 wt.% of an aqueous phase and about 70 to about 30 wt.% of an oil phase, based on the total weight of the emulsion. The oil phase essentially comprises the bituminous binder. The amount of the (1— »3)-P-D-glucan in the emulsion is preferably 0.0005 wt.% to 0.1 wt.%), based on the total weight of the emulsion, more preferably 0.0005 wt.% to 0.05 wt.%, even more preferably 0.0005 wt.% to 0.02 wt.%

The amount of the cationic emulsifier in the emulsion is preferably 0.01 wt.% to 20.0 wt.%), more preferably 0.01 wt.% to 10.0 wt.%, even more preferably 0.01 wt.% to 5.0 wt.%, yet even more preferably 0.02 wt.% to 2.5 wt.% even yet more preferably 0.02 wt.%) to 0.5 wt.%) and in particular 0.02 to 0.2 wt.%, based on the total weight of the emulsion.

When present in the emulsions according to the present invention, the elastomer and/or the petroleum resin and/or the natural resin content is preferably 0.01 to 10.0 wt. %, more preferably 0.05 to 7.5 wt. %, of the elastomer and/or the petroleum resin and/or the natural resin, based on the total weight of the emulsion.

The bituminous emulsions according to the present invention are fast breaking and have excellent storage stabilities. Accordingly, the bituminous emulsions according to the present invention are characterized by a breaking index of 150 or less, preferably of 130 or less. A breaking index of 150 or less, preferably 130 or less, ensures in a sufficiently low breaking time of the emulsion when it is applied to a road surface, even under relatively humid and cold conditions which allows the use of such emulsions under less advantageous weather conditions.

In addition, the bituminous emulsions according to the present invention are characterized by a C-factor of 200 or less, preferably 150 or less and even more preferably 115 or less. The C-factor is defined herein as:

C-factor = Penetration recovered binder (10 ¹ mm) x (100 x Storage stability) ³ ' ⁵ wherein the penetration is determined according to ASTM D D5-97 and the storage stability is determined according to NEN-EN 12847. The storage stability is the difference between the water content of the aqueous phase and the oil phase formed after separation. The lower the value of the difference, the better the storage stability. The storage stability is often expressed in a percentage and then this value must be multiplied by 100%.

The present invention also relates to a process for chip sealing a road surface, wherein an emulsion is applied to said road surface followed by embedding a particulate material, wherein said emulsion comprises a (1— »3)-P-D-glucan, a cationic emulsifier, and a bituminous binder having a penetration of less than 70 10 ^"1 mm according to ASTM D5-97, wherein the average diameter of the particulate material is 3 mm or less, preferably less than 2 mm, and wherein the application rate of the particulate material is 0.1 - 0.6 kg/m ³ .

Examples

Example 1

A mixture of scleroglucan (Actigum® CS 6 purchased from IMCD, the Netherlands; scleroglucan content is about 83 wt.%) and a food grade vegetable oil (purchased from Mosselman N.V., Belgium, or Heybroek B.V., the Netherlands) was prepared by mixing the two components at room temperature in a weight ratio of 1 : 2. The food grade vegetable oil protects the scleroglucan particles to conglomerate in an aqueous medium and hence a homogenous dispersion is obtained when this mixture is added to water whilst stirring.

Emulsions were produced according the following procedure. To 99.232 units of weight of water at a temperature of about 60°C, 0,428 units of weight of a 30%> hydrochloric acid solution was added whilst gently stirring. After the addition of 0.24 units of weight of Redicote® E9 fatty amine emulsifier (purchased from Akzo Nobel) to the water, 0.1 units of weight of the scleroglucan- food grade oil (1 : 2) mixture was added. Both the water and a hard bitumen were fed to an Atomix emulsification unit (Emulbitume, France) and were emulsified to an oil in water (O/W) emulsion having a water content of about 40 wt.% water. The emulsions were prepared with the following hard bitumen: 40 - 60 10 ^"1 mm (ex-Total Antwerp Belgium refinery), 35 - 50 10 ¹ mm and 20 - 30 10 ^"1 mm (both from ex-Total Dunkirk France refinery. For these emulsions, a double amount of the Actigum® CS 6 - food grade oil (1 : 2) mixture was used (0.2 wt. %) Emulsion properties are listed in Table 1 below. Table 1

Table 2

The storage stability was measured according to NEN-EN 12847 after 7 days of storage at ambient temperatures (18 - 22°C) and the results are presented in Table 2.

This example clearly demonstrates that very storage stable bitumen emulsions can be produced by using only a small amount of Actigum® CS 6 in the aqueous phase.

Example 2

A bitumen emulsion was prepared according to the procedure as described in Example 1. A 40 - 60 10 ^"1 mm bitumen was used (ex-Total Antwerp Belgium refinery) and 0.14 units of weight of a Actigum® CS 6 - food grade oil (1 :2) mixture was used. Prior to emulsification, the water mixture was filtered using a glass wool filter so Actigum® CS 6 particles, which were not dissolved, were removed from the aqueous phase. It was not possible to quantify the amount of Actigum® CS 6 recovered by filtration as most of the material was filtered off. However, the storage stability of the emulsion used was similar as the storage stability for the unfiltered material. The results are presented in Table 3.

Table 3

Table 4

Example 3

An emulsion was prepared according to the method of Example 1 from a 10 - 20 10 ^"1 mm bitumen (ex Total Dunkirk France refinery). This material is a glass-like material with a relatively high softening point (ring & ball temperature » 55 °C).

The emulsification process with the 0 % Actigum® CS 6 addition (Sample I) was not stable. However, it was possible to collect a sample which was stable for at least one day. The properties of the sample are presented in the Table 5. The emulsification with the 0.2 wt. % addition of an Actigum® CS 6 - food grade vegetable oil (1 : 2) mixture (Sample II) went much more smoothly and it was possible to continuously produce a homogeneous emulsion.

Table 5

The storage stability of these samples was judged visually (Table 6). Table 6

Example 4

A mixture of scleroglucan (Actigum® CS 6 purchased from Cargill, France; scleroglucan content about 83 wt.%) and a food grade vegetable oil (purchased from Mosselman N.V., Belgium, or Heybroek B.V., the Netherlands) was prepared by mixing the two components at room temperature in a weight ratio of 1 : 2. The food grade vegetable oil protects the scleroglucan particles to conglomerate in an aqueous medium and, hence, a homogenous dispersion is obtained when this mixture is added to water whilst stirring. Emulsions were produced according the following procedure. To 99.009 units of weight of water at a temperature of about 60°C, 0,467 units of weight of a 30% hydrochloric acid solution was added whilst gently stirring. After the addition of 0.324 units of weight of Redicote® E9 fatty amine emulsifier (purchased from Akzo Nobel) to the water, 0.2 units of weight of the scleroglucan- food grade oil (1 : 2) mixture was added. Both the water and a hard bitumen, i.e. Total bitumen with a penetration ranging from 20-30 10 ^"1 mm (Total refinery Dunkirk) were fed to an emulsion mill (a Trigonal Mill obtained from Siefer Machinenfabrik GmbH & Co KG) and were emulsified to an oil in water (O/W) emulsion having a water content of about 41 wt.% water. The storage stability was determined after seven days. The compositions and properties of the emulsions are summarised in Table 7.

Table 7

^(a) Equivalent to ASTM D5-97.

After production the emulsion was packed in 1000 liter containers. Ten days later, the emulsion was re-packed in 25 kg buckets and brought to a job site where it was applied to an old DAB asphalt top layer of seven years old under the following weather conditions: asphalt temperature was about 20°C, air temperature was about 22°C and relative humidity was about 61%. The rate of application using a roller brush was about 0.6 kg/m ² . After 5 minutes when the emulsion started to break visually, sand (average diameter of less than 2 mm) was applied at a rate of 0.05 - 0.1 kg/m ² . After 30 minutes, the emulsion coagulated fully and the job was opened for traffic. No wheel tracks were visible and both sides of the job, so a surface was obtained without the use of aggregates with an average diameter of 2 mm or more.

The same emulsion was used in a different project as a surface treatment on recently constructed but damaged DAB. The treatment was performed under the following weather conditions: environmental temperatures between 1 1.2° - 16.6°C, relative humidity 68%. The emulsion was sprayed using a standard tack coat emulsion spraying unit; the spraying temperature was 64°C, spraying rate was 0.6-0.8 kg/m ² . Shortly after application (before the emulsion was fully broken) the surface was sanded (0.3-0.5 kg/m ² ) using crushed stone (about 0-3 mm).