AU3781300A

AU3781300A - Bituminous emulsions, and their use for the production of materials and of road pavements

Info

Publication number: AU3781300A
Application number: AU37813/00A
Authority: AU
Inventors: Giles Barreto; Dominique Rouet
Original assignee: Carbonisation et Charbons Actifs CECA SA
Current assignee: Carbonisation et Charbons Actifs CECA SA
Priority date: 1999-06-01
Filing date: 2000-05-31
Publication date: 2000-12-07
Also published as: NO20002711D0; MXPA00005310A; NZ504869A; KR20010069202A; BR0009624A; ATE279478T1; FR2794468A1; EP1057873A1; FR2794468B1; NO20002711L; EP1057873B1; ES2231137T3; DE60014765D1

Abstract

The addition of a specified surfactant to the bituminous emulsion enables the preparation of road surface coatings which stabilize quickly to allow re-opening to traffic. The bituminous emulsion comprises a binder, water, a cationic, anionic or non-ionic emulsifier and also a surfactant additive selected form : (a) a non-ionic polyoxyethylated surfactant conforming to the crude formula :- Rx(O(C2H4))yOH or RxCO(O(C2H4))yOH ; (b) a product of the formulae above; (c) an amphoteric surfactant, alone or mixed, of the crude formula :- Rx(N+(CH3)2)(CH2)yA or RxNH(CH2)yCOOH or RxNH(CH2)y B; (d) amphoteric surfactants of formulae as in (c); (e) an alkanolamide surfactant of crude formula :- RxCONH(CH2)yOH or RxCONH((CH2)yOH)((CH2)zOH) ; -Rx represents chains as in (a); (f) N amine oxide of crude formula :- Rx(CH3)2N---O -Rx represents chains as in (a) ; Rx = a carbyl chain(optionally unsaturated and substituted), an alkyl(ene)phenyl or either of these in which H is partially or totally substituted by F; a poly(dimethylsiloxane) chain (x is the number of Si atoms); x = number of C atoms in the chain; 7 - 22; y = number of ethylene oxide motifs; 0 - 8 (preferably less than or equal to 6) for the first formula; 2 - 8(preferably less than or equal to 6) for the second formula ; 0 - 4. A = COO-, OSO3- or OSO2- ; B = OSO3- or OSO2- ; C = a cationic ion of an alkali, alkaline earth, Fe, Cu, Mn or Zn, or ammonium to impart electrical neutrality; y = number of CH2 motifs ; x = 4 - 15 ; y, z = number of ethylene oxide motifs ; z = 1 - 4 ; Independent claims are also included for: (1) preparation of the emulsion; (2) the surface coating material; (3) the coating.

Description

S&FRef: 510132

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: CECA S.A.

4 8 Cours Michelet 92800Puteaux France Gilles Barreto Dominique Rouet Spruson Ferguson St Martins Tower 31 Market Street Sydney NSW 2000 Bituminous Emulsions, and their use for the Production of Materials and of Road Pavements The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c The present invention relates to the manufacture of bituminous emulsions and to road pavements obtained at ambient temperature generally between 0°C and 40'C) from aggregate and such emulsions.

The majority of bituminous emulsions comprise a bituminous binder; a cationic surfactant (in the case of cationic emulsions), an anionic surfactant (in the case of anionic emulsions) or a nonionic surfactant (in the case of nonionic emulsions); and water. Cationic emulsions are of particular interest, as a result of both the speed at which they break on aggregates and the adhesion properties which are generally obtained between the aggregate and the broken emulsion, giving the road pavements that have 10 just been produced good mechanical properties. In addition to the abovementioned components, cationic emulsions are often acidified by adding acid to the aqueous phase used in the manufacture of the emulsion and anionic emulsions are generally manufactured in an alkaline medium.

The bituminous materials obtained by coating or contacting aggregates with bituminous emulsions have been known for a long time. Those skilled in the art make a distinction, in particular, between poured cold, open-graded, semidense-graded, densegraded and storage-grade mixes, emulsion-stabilized gravel, surface coatings and bond coats.

A first type of bituminous material (type 1) used in the production of road pavements consists of cold poured mixes. In this case, the problem of application is Ssolved in most cases if the rules of the art are followed, since the mix is applied in the form of a "soup" a few seconds after it has been manufactured. It is, however, necessary to increase cohesion. This is generally performed without an external stress, by a chemical and physical change in the system, although in some cases a compacting operation is carried out. This change involves the coalescence of the bitumen of the emulsion and is accompanied by a spontaneous departure of the aqueous phase.

Although the first phenomenon is quite well controlled by those skilled in the art, who can control the formulation of the emulsion and the nature and amount of breaking additive, a technical solution for controlling the second lhenomenon does not exist.

This may lead to insufficient cohesion initially.

A second type of bituminous material (type 2) comprises open-graded, semidense-graded and dense-graded cold mixes, storage-grade cold mixes and emulsionstabilized gravel. In the majority of cases, optimizing the choice of emulsion (nature and amount of the emulsifier, bitumen concentration and pH) can solve, partially or completely, the problems associated with coating, transportation and application of the mix in its swollen form. However, once the swollen mix has been spread out in the form of a pavement, the compacting step is carried out. The purpose of this step is to increase the cohesion, that is to say to ensure good adhesion between bitumen and aggregate, so 10 as to allow the pavement to withstand traffic. This may be temporarily interrupted during application in the case of the repair or renovation of roadways. Cohesion is obtained by the material densifying, accompanied by the expulsion of the aqueous phase .ooo and air. Cold coated materials exhibit a high degree of friction, which impedes the densifying operation. The degree of compactness obtained cold is very often inferior to the degree of compactness obtained using the same materials coated hot with the same binder. However, it is well known to those skilled in the art that the degree of compactness and the extent of water expulsion during compacting allow assessment of the cohesion of the cold densified material. Thus, it is found that successful construction of roadways subjected to heavy traffic (T 1 or higher) depends not only on the technique 20 but also on the meteorological conditions on the day the work was carried out and even on the following day. Bright sunshine, high temperatures or strong winds contribute to the drying of the pavement and to its increased cohesion.

In all such cases of application of cold mixes (storage-grade, open-graded, semidense-graded, dense-graded and poured mixes and emulsion-stabilized gravel), rapidly (re)opening to traffic poses more problems the heavier the traffic. In the event of premature opening, the film of water generally present between the coarsest aggregate particles and the binder coat prevents the formation of adhesion contact between binder and aggregate. There is a loss of aggregate which weakens the pavement with respect to pounding and simultaneously degrades its surface quality. Only evaporative drying -3allows this aqueous film to disappear once the roadway has been (re)opened to traffic. It is therefore advantageous to be able to remove as much of the water as possible during the application period and to improve the effectiveness of the pavement compacting operation.

A third type of bituminous material (type 3) comprises surface coatings, obtained by successive application of one or more bituminous emulsion coats and of one or more aggregate courses which interpenetrate during compacting by a setting-in of the aggregate particles within the emulsion in the process of breaking up. In order to prevent the emulsion, once it has been applied on the ground, from flowing beyond the boundaries of the roadway that is in the process of being produced, particularly in the case of sloping roadways, it is necessary to increase its viscosity, for example by increasing the amount of bitumen that it contains to above 65% by volume or else by adding a viscosity modifier to it. Increasing the concentration of bituminous binder is generally detrimental to the fineness of the emulsion, which may lead to stability S 15 problems during its storage. Even without working at high bituminous binder concentrations, seeking high levels of emulsion reactivity for coatings means that little emulsifier is used, thus leading to long-term storage problems. The third type of bituminous material also includes bond coats obtained by spraying a rapidly breaking .ooo emulsion, often used hot on a support. Since breaking has to be rapid, the amount of 20 emulsifier used is small, which may also lead to stability problems during long-term storage. These problems are exacerbated when the bitumen is difficult to emulsify, a situation encountered in the case of bond coats without surface adhesion, for which the bonding emulsion contains a bituminous binder of low penetrability.

In practice, it appears that the behaviour of the cold mixes of the prior art is greatly influenced by the amount of water added. It is found that the useful watercontent range is narrow and therefore must be strictly controlled in order to be able to obtain road pavements of satisfactory quality, thereby requiring very rigorous control of the entire emulsion preparation process, then of the mix and finally of the road pavement in order to avoid any undesirable deviation which may irpair the quality of the final -4road pavement. It would therefore also be advantageous to be able to reduce such sensitivity to the amount of water added.

The present invention provides bituminous emulsions, cold mixes and emulsion-stabilized gravel (of types 1 and 2) which can be used for producing road pavements and which surprisingly exhibit improved water expulsion, spontaneously in the case of the first type immediately after application without compacting and during compacting in the case of the first and second types, as well as improved compactness with respect to the road pavements of the prior art, without changing the operating conditions during the steps of manufacturing the bituminous emulsions and the mixes, 10 during their storage and their possible transportation, their unloading, their application "and their possible compacting. The present invention also provides surface-coating emulsions and surface coatings, and bond-coat emulsions and bond coats (of type 3) which can be used for the production of road pavements. These emulsions have improved storage capabilities and may have higher viscosities without using the viscosity modifiers of the prior art and without increasing the concentration of bitumen.

The present invention is particularly advantageous, especially in the case of roadway *...renovation, insofar as it allows road pavements to be obtained which can be reopened very quickly to road traffic without it being necessary to wait several hours, or several days, for the evaporation of the residual aqueous phase not expelled during the breaking 20 of the emulsion and during the possible compacting. The rapid stabilization of the road pavements according to the invention is of obvious economic advantage.

Compared with the emulsions and the mixes of the prior art, whose behaviour and quality of the road pavement resulting therefrom are greatly influenced by the amount of water added, the emulsions and mixes according to the invention allow good-quality road pavements to be obtained, while allowing considerably large variations and deviations in the amount of water added. This operating margin assists the manufacture of the mixes of the present invention. The emulsions according to the invention are also easy to handle.

According to one aspect of the invention, there is provided a bituminous emulsion comprising at least one bituminous binder, water and at least one cationic, anionic or nonionic emulsifier, characterized in that it comprises at least one surfactant additive which is: a) a polyethoxylated nonionic surfactant of formula: Rx[O(C 2

H

4 )]yOH or RCO[O(C 2

H

4 )]yOH where Rx represents a substituted or unsubstituted, saturated or unsaturated, linear or branched carbon chain, or an alkyl(ene)phenyl, or one of the above chains in which the hydrogen is partly or completely substituted with fluorine; x represents the number of carbon atoms of the carbon chain or of the 10 alkyl(ene)phenyl; y represents the number of ethylene oxide units; 7 x 22 and 0 y 8 for surfactants corresponding to the first formula; and 7 x 22 and 2 y 8 for surfactants corresponding to the second formula; b) a polyethoxylated nonionic surfactant of formula: 15 R[O(C 2

H

4 )]yOH or R.CO[O(C 2

H

4 )]yOH where Rx represents a linear or branched poly(dimethylsiloxane) chain; x represents the number of silicon atoms; y represents the number of ethylene oxide units; and 4 x 15 and 4 y S 20 c) an amphoteric surfactant of formula: Rx[N (CH 3 2

(CH

2 )yA, RNH(CH 2 )yCOOH or RxNH(CH 2 )yB,C where Rx is as defined in a); A represents COO-, OSO3- or OSO2; B represents OSO- or OS02-; C represents the cationic counterion of an alkali metal or alkaline earth metal, iron, copper, manganese or zinc, or the ammonium cation, in a proportion such that the salt is electrically neutral, y represents the number of CH 2 units; and 7 s x 22 and 0 y 4;

SI

-6d) an amphoteric surfactant of formula: Rx[N+(CH 3 2 ](CH2)A, RxNH(CH 2 )yCOOH or RxNH(CH 2 )yB,C where Rx is as defined in b); A, B, C and y are as defined in and 4x 15and0 y <4; e) an alkanolamide surfactant of formula:

RCONH(CH

2 )yOH or RCON[(CH 2 )yOH] [(CH 2 )zOH] where Rx is as defined in a); y and z represent the number of CH 2 units; and 10 7 x 22, 1 y 4 and 1 z 4; or f) an amide-oxide surfactant of formula: Rx(CH 3 2

NO

where Rx is as defined in and 7 g x 22.

15 According to a second aspect of the invention, there is provided a process for preparing a bituminous emulsion according to the invention, which process comprises Smixing a surfactant additive with a cationic, anionic or nonionic emulsifier before the manufacture of the emulsifying or dispersed phase, either in the emulsifying phase before the manufacture of the emulsion or in the emulsion at any time between the end S 20 of emulsification of the emulsion and its use.

The emulsions according to the invention are characterized in that they comprise, in addition to the usual cationic, anionic or nonionic emulsifier(s), the bituminous binder and water, at least one surfactant additive. These surfactant additives, used alone or in combination, may be mixed with the cationic, anionic or nonionic emulsifier(s) before the manufacture of the emulsifying or dispersed phase, either in the emulsifying phase as manufactured according to the art using cationic, anionic or nonionic emulsifiers before the manufacture of the emulsion, or in the emulsion manufactured according to the art using cationic, anionic or nonionic emulsifiers, at any time between the end of emulsification of the emulsion and its use. It is possible to add water, which serves to wet the aggregate. In this case, in order to facilitate dispersion, water may be added by means of a nonionic emulsifier, or this may be done in acid medium in the presence of a cationic emulsifier or in basic medium in the presence of an anionic emulsifier. It is also possible to incorporate part of the surfactant additive in the emulsion and the rest in the added water serving to wet the aggregate. In the present description, a distinction is made between an emulsifier and a surfactant additive (a surfactant): an emulsifier is a chemical which makes it possible, within the meaning of the prior art, to put a bituminous binder into an emulsion, whereas a surfactant additive is a chemical which, added to a bituminous emulsion formulation according to the prior 10 art, makes it possible to obtain a bituminous emulsion according to the present invention.

The surfactant additives employed in the cationic, anionic or nonionic Semulsions according to the invention may be especially chosen from: a) polyethoxylated nonionic surfactants, alone or as a mixture, of 15 formula:

R[O(C

2

H

4 )]yOH or R.CO[O(C 2

H

4 )]yOH where Rx represents either a substituted or unsubstituted, saturated or "unsaturated, linear or branched carbon chain, or an alkyl(ene)phenyl, or one of the above chains for which the hydrogen is partly or completely 20 substituted with fluorine; x represents the number of carbon atoms of the carbon chain or of the alkyl(ene)phenyl; and y represents the number of ethylene oxide units; with 7 x 22, 0 y 8 and preferably y 6 for the molecules corresponding to the first formula and with 7 x 22, 2 y 8 and preferably y 6 for the molecules corresponding to the second formula.

Preferred nonionic surfactants for use according to the present invention include polyethoxylated alkyl(ene) ethers for which 6 c 22 and 2 s y s 6, 1 polyethoxylated alkyl(ene) esters for which 5 g x g 21 and 2 y 6, and polyethoxylated alkyl(ene) phenols for which 6 s x 22 and 2 s y g 6, alone or as a mixture; b) polyethoxylated nonionic surfactants, alone or as a mixture, of formula: Rx[O(C 2

H

4 )]yOH or RCO[O(C 2

H

4 )]yOH where Rx represents a poly(dimethylsiloxane) chain for which x represents the number of silicon atoms, the chain being linear or branched; and y represents the number of ethylene oxide units; 10 with 4 x 15 and 4 s y c) amphoteric surfactants, alone or as a mixture, of formula:

R[N'(CH

3 2

](CH

2 )yA or RNH(CH 2 )yCOOH or RNH(CH 2 )yB,C where Rx is as defined in a), A represents either the COO- group or the OSO3" group or the OSO"- group, 15 B represents either the OSO3 group or the OSO2 group, C represents either the cationic counterion of an alkali metal or alkaline earth metal, iron, copper, manganese or zinc, or the ammonium cation, in a proportion such that the salt is electrically neutral, and y represents the number of CH 2 units, 20 with 7 x 22 and 0 y s 4; d) amphoteric surfactants, alone or as a mixture, of formula: Rx[N+(CH 3 2

](CH

2 )yA or RxNH(CH 2 )yCOOH or RxNH(CH 2 )yB,C where Rx is as defined in b), A, B and C are as defined in c) and C is present in a proportion such that the salt is electrically neutral, and y represents the number of CH 2 units, with 4 g x 15 and 0 y 4; e) alkanolamide surfactants, alone or as a mixture, of formula: RxCONH(CH 2 )yOH or RxCON[(CH 2 )yQH][(CH 2

),OH]

*L -9where Rx is as defined in a), with 7 x 22, 1 y 4 and 1 z 4; f) amine-oxide surfactants, alone or as a mixture, of formula: Rx(CH 3 )2NO where Rx is as defined in a), with 7 x 22.

The concentration of nonionic surfactant additive(s) of the emulsions according to the invention will generally not be less than 0.2 kg per tonne of emulsion nor greater than 8 kg per tonne of emulsion. The amount of surfactant additive added is 10 assessed with respect to the concentration of cationic, anionic or nonionic emulsifier(s) used by those skilled in the art. The concentration of surfactant additive(s) used therefore depends on the type of bituminous material. Generally, this concentration will not exceed the concentration of cationic, anionic or nonionic emulsifier(s) of the emulsion.

The chemical nature and the amount of surfactant additive(s) allowing the abovementioned applicative properties to be optimized depend on the aggregate used for the type 1 and type 2 bituminous materials.

Cationic emulsifiers suitable for manufacturing the cationic emulsions and the bituminous materials according to the invention include the usual cationic emulsifiers, especially: alkyl(ene) polyamines, and more particularly tallow (poly)propylene polyamines such as tallow propylenediamine (EINECS definition: amines, N-tallow alkyltrimethylenedi-, RN 61791-55-7) represented from an industrial standpoint by DINORAMI S from Ceca tallowdipropylenetriamine (amines, (N-tallow) alkyldipropylenetri-, RN 61791-57-9) and tallow tripropylenetetramine (amines, (N-tallow) alkyltripropylenetetra-, RN 68911-79-5), the latter being well represented from an industrial standpoint by POLYRAM®S from Ceca S.A.; alkoxylated alkyl(ene) polyamines and more particularly propoxylated tallowdipropylenetriamine (amines, (N-tallow) 2-propanol-[[[(3-aminopropyl)amino]-3-propyl]imino]-1,1'bis, RN 97592-79-5), the latter being well represented from an industrial standpoint by POLYRAM®SL from Ceca S.A.; quaternary ammonium salts such as tallow propylenediamine quaternized to methyl chloride (composed of the quaternary ammonium ion, pentamethyl tallowalkyltrimethylenedi-, chloride, RN 68607-29-4) well represented, for example, by 10 STABIRAM®MS3 from Ceca S.A.; alkyl(ene)amidoamines and more specifically tallow or tall-oil alkyl(ene)amidoamines, their alkylimidazoline cyclization derivatives, or their mixtures (produced from the condensation of

C

8

-C

2 2 fatty acids with C 2

-C

3 polyalkylene polyamines and with 15 ethanolamines, their mixtures and amide cyclization products ~obtained), these being well represented by the emulsifier from Ceca S.A.

The concentration of cationic emulsifier(s) of the emulsions according to the invention will generally not be less than 0.8 kg per tonne of emulsion nor greater than 20 kg per tonne of emulsion. The concentration of cationic emulsifier(s) used also depends on the type of bituminous material.

Usually it is preferred to add a certain amount of acid to the aqueous phases of the cationic emulsifier(s).

Anionic emulsifiers suitable for manufacturing the anionic emulsions and bituminous materials according to the invention include the usual anionic emulsifiers, especially alkyl(ene)carboxylates, alkyl(ene)sulphates and alkyl(ene)sulphonates, alkyl(ene)aryl(ene)carboxylates, alkyl(ene)aryl(ene)sulphates and alkyl(ene)aryl(ene)sulphonates as well as alkyl(ene)(aryl(ene)) phosphoric esters with an alk(en)yl or alkyl(ene)(aryl(ene)) chain comprising between 8 and 22 carbon atoms.

-11- Usually it is preferred to add a certain amount of base to the aqueous phases of the anionic emulsifier(s).

The concentration of anionic emulsifier(s) of the emulsions according to the invention will generally not be less than 0.8 kg per tonne of emulsion nor greater than kg per tonne of emulsion. The concentration of anionic emulsifier(s) used also depends on the type of bituminous material.

Nonionic emulsifiers suitable for manufacturing the nonionic emulsions and the bituminous materials according to the invention include the usual nonionic emulsifiers, especially alkyl(ene) poly(oxyethylene)alcohols and alkyl(ene)-aryl(ene)- *o*o4 poly(oxyethylene) alcohols, with an alk(en)yl chain comprising between 8 and 22 carbon atoms and a number of ethylene oxide units greater than or equal to 9.

i The concentration of nonionic emulsifier(s) of the emulsions according to the invention will generally not be less than 0.8 kg per tonne of emulsion nor greater than 20 kg per tonne of emulsion. The concentration of nonionic emulsifier(s) used also depends on the type of bituminous material.

Bituminous binders suitable for use according to the present invention include the bituminous binders usually employed in bituminous emulsions for type 1, type 2 and type 3 materials; their penetrability is generally between 20/30 and 500.

The emulsions may be prepared with one or more binders; in the latter case, 20 either the various binders are mixed hot before emulsification, or 2 (or more) emulsions are prepared, each containing a binder that will be subsequently mixed to give a socalled hybrid emulsion which will be brought into contact with the aggregate in order to produce the mix. An example of the preparation of a hybrid bituminous emulsion is explained in detail in European patent specification EP 589,740 in the name of CECA the content of which is incorporated as reference. This patent describes hybrid emulsions one based on a soft bituminous binder and the other based on a hard bituminous binder in order to improve the workability of the mix while still maintaining good mechanical strength of the final road pavement.

The present invention also relates to type 1 nd type 2 bituminous materials and road pavements obtained: either from the bituminous emulsions according to the invention, as defined above, and from aggregate which may be wetted with added water, the water itself possibly containing at least one surfactant additive; or from usual bituminous emulsions not containing any surfactant additive as defined above) and from aggregate wetted with the added water containing at least one surfactant additive.

According to a 1hird aspect of the invention, there is provided a material obtainable by coating or contacting a) an aggregate or road support with a bituminous emulsion as defined above, and/or Sb) an aggregate wetted with water or an aqueous solution comprising at least one surfactant additive as defined above, with a bituminous emulsion as defined above.

15 According to a fourth aspect of the invention, there is provided a material obtainable by contacting an aggregate wetted with an aqueous solution comprising at least one surfactant additive as defined above, with a bituminous emulsion which does •o o not contain a surfactant additive as defined above.

I These types of cold mix (1st and 2nd types), namely poured mixes, opengraded, semidense-graded and dense-graded mixes, storage-grade mixes and emulsionstabilized gravel, are obtained by mixing the aggregate wetted with the added water and the bituminous emulsion according to known techniques and by means of known equipment. The aim in these cases, is to obtain improved compactness and a greater amount of water removed, once all the steps before opening to traffic have been carried out. According to the invention, in the case of emulsion-stabilized gravel, storage-grade or cold open-graded mixes, cold semidense-graded mixes and cold dense-graded mixes, the improved expulsion of water takes place during compacting. The improvement in the compactness is visible at the end of compacting. According to the invention, in the case of cold poured mixes, the improved water expulsion takes place without external stress, -13in a spontaneous manner. In the latter case, there may also be an improvement in the compactness, although there is virtually no external stress, by self-compacting due to the effect of gravity. To improve the immediate and final cohesion, it is possible to carry out a compacting step: in this case, the reduction in porosity and the increase in water expulsion are greater in the case of type 1 mixes according to the invention. For these types (1 and 2) of material, the coating, emulsion-breaking, possible transportation, unloading and application steps are carried out in the same way and therefore do not require any modification to the equipment or modifications to the settings.

The materials of the present invention may be of the bond-coat type. The 10 bond-coat may be obtained by spraying a bituminous emulsion on a road support.

.The cold (type 3) surface coatings are prepared by applying one or more aggregate courses and one or more coats of bituminous emulsion by means of which the surface intended to receive the road pavement is successively covered using the standard techniques and apparatus; the road pavement is obtained after breaking of the emulsion 15 and compacting. In the case of a steeply sloping support, high emulsion viscosities are required. The solutions currently used consist in increasing the bitumen concentration above 65% and/or adding thickeners to the continuous phase. Given also the high reactivities required of the emulsion, and therefore the small amounts of emulsifier used, there is often the problem of storage stability of emulsions for coatings. The problems 20 encountered during the manufacture and use of emulsions for bond coats (type 3) are the same. They are even exacerbated when it is desired to use a binder having a very low penetrability since this binder is more difficult to emulsify: this is the case with emulsions for "tack-free" bond coats. According to the present invention, a sufficient addition of the surfactant additives described above to a formulation used by those skilled in the art allows the viscosity to be increased without modifying the emulsification (if it is added to the emulsifying phase): the breaking kinetics are hardly modified. In addition to even larger amounts of surfactant additive added, it may be necessary to revise upwards the amount of nonionic, anionic or cationic emulsifier used by those skilled in the art so as to keep the breaking kinetics constant. In this case, the

I

-14emulsification and the storage stability are greatly improved and the viscosity increased.

There is thus the possibility, by adding surfactant additives according to the invention, of obtaining modified breaking kinetics a viscosity high enough to avoid the problems of streaking as well as improved storage stability.

EXAMPLES

Preparation of the emulsion In Examples 1 to 4, cationic bituminous emulsions are prepared from a 10 mixture of cationic emulsifier, acid, bituminous binder and water, to which the surfactant S•additive is added just before the start of the phase of mixing with the aggregate in order to prepare the mix.

In Examples 5, 7 and 8, a cationic bituminous emulsion is prepared from water to which the nonionic surfactant additive has been added cationic emulsifier, S 15 acid and bituminous binder.

In Example 6, a cationic bituminous emulsion containing no nonionic surfactant additive is prepared, a mix according to the invention being prepared from this emulsion by mixing it with aggregate wetted with added water to which nonionic surfactant additive, cationic surfactant and acid are added.

20 In Example 9, a cationic bituminous emulsion is prepared from a mixture of cationic emulsifier, acid, bituminous binder and water, to which a nonionic surfactant additive based on a fluoroalkyl chain is added just before the start of the phase of mixing with the aggregate in order to prepare the mix.

Preparation of the mix The aggregate is placed in a planetary mixer (SR Consulting, type speed of rotation 30 rpm) and mixed for 30 s. Next, the added water is poured in and mixing is resumed for a further 30 s before the emulsion is added. The mixing of all the components of the mix is continued for one minute and then the mix thus obtained is stored for one hour in a kettle before it is introduced into the mould and compacted.

Preparation of the road pavement The mixes are compacted using a Gyratory Shear Compactor (Invelop Oy ICT-100RB model): On leaving the kettle, the mix is placed in a GSC mould (cylindrical mould 100 mm in diameter and 25 cm in height) and then subjected to a compressive load of 0.6 MPa, with a 10 clearance angle, for N revolutions or gyrations. The number of revolutions carried out depends on the type of application: 30 revolutions for cold open-graded mixes and 120 gyrations for cold dense-graded mixes. At the end of compacting, the test piece i. again weighed, thereby allowing the percentage of water expelled during the compa6ting to be calculated. The void content is calculated by 10 measuring the height of the pavement before and after compacting.

Performance evaluation i°o ~The improvement in the performance of the emulsions and road products according to the present invention was assessed by comparing formulations according to the prior art (containing no surfactant additive) with formulations according to the 15 invention (containing surfactant additive). In order for the comparison to be valid in the following tests, the same cationic emulsifier was used in both formulations. On the other hand, in some cases the concentration of cationic emulsifier is not the same for both formulations so as to maintain similar breaking kinetics and therefore to keep the S: .settings used in the field constant. The expression "similar breaking kinetics" should be 20 understood to mean kinetics such that the times taken for the emulsion to break (determined visually) do not differ by more than 25%. It is in fact possible that, when a surfactant additive is present, at a constant concentration of cationic emulsifier, the breaking kinetics are modified, which would therefore require the settings used in the field to be modified, something which is not desirable.

Example 1 (cold open-graded mix) A cold open-graded mix is prepared according to the operating method described above. The aggregate used is a hornfels, the particle size distribution of which is as follows: -16- 0/2 mm 44% 2/4 mm 12% 6/10 mm 44% The filler content (aggregate particles passing through an 80 lim screen) is about 8% by weight.

The added-water content in the mix is 4 g per 100 g of aggregate.

The bituminous emulsion contains: 61% by volume of a 70 penetrability bitumen sold by Elf; 6 kg of cationic emulsifier (POLYRAMv®SL sold by Ceca, which has 10 been acidified with hydrochloric acid so that the pH of the soap is 2) per 1000 kg of water bitumen; S- 1.3 kg of nonionic surfactant (alcohol with a fatty chain of 18 carbon atoms (oleic chain), sold under the brand name ROFANOL®, ethoxylated with 4.5 mol of ethylene oxide per mole of alcohol on average) per 1000 kg of added water bitumen cationic surfactant acid. The bitumen content in the mix is 6 g per 100 g of aggregate.

Under the same operating conditions and by way of comparison, a cold mix is prepared using aggregate, added water and a bituminous emulsion which differs from the bituminous emulsion described above in that it contains no nonionic surfactant.

20 Three compacting tests were carried out with each cold mix according to the operating method described above. For each test, the porosity and the water expulsion at the end of the compacting operation, after 30 gyrations, is determined and the average calculated over these 3 tests. The results are given in Table 1.

-17- Table 1 10 Type of mix Test No. Porosity Expelled water Open-graded mix 1 1 17.3 without nonionic 1 -2 17.7 17 surfactant 1-3 17.4 18.4 Average 17.5 16.8 Open-graded mix 1 -4 16.7 25.4 according to the 1 5 16.3 23.7 invention 1-6 16.5 23.3 SAverage 16.5 24.1 It is found that the presence of nonionic surfactant increases the final compactness and the water expulsion of the mix.

It may also be pointed out that, on average, the appearance of water occurs earlier in the case of the mix containing the nonionic surfactant, but that the breaking kinetics of the 2 emulsions are similar.

Example 2 (cold open-graded mix) A cold open-graded mix is prepared according to the operating method described above. The aggregate, the bitumen and the cationic emulsifier used are identical to those of Example 1; the contents of aggregate, added water, bitumen and cationic emulsifier employed are identical to those of the mix of Example 1. On the other hand, the nonionic surfactant used is an acid based on a fatty chain having 18 carbon atoms (oleic chain), the acid being ethoxylated with 6 mol of ethylene oxide per mole of acid on average; it is added to the emulsion already manufactured in an amount of 1.6 kg per 1000 kg of water bitumen cationic surfactant acid.

Under the same operating conditions and by way of comparison, a cold mix is prepared from a bituminous emulsion which differs from the bituminous emulsion described above in that it contains no nonionic surfactant.

Three compacting tests were carried out with each cold mix according to the -18a a 10 operating method described above. For each test, the porosity and the water expulsion at the end of the compacting operation, after 30 gyrations, are determined and the average calculated over these 3 tests. The results are given in Table 2.

Table 2 Type of mix Test No. Porosity Expelled water Open-graded mix 2 1 16.55 18 without nonionic 2 2 17.8 17 surfactant 2-3 18.6 16.3 Average 17.65 17.1 Open-graded mix 2 4 16.3 27.55 according to the 2 5 17.1 19 invention 2-6 16.8 Average 16.7 22.2 It is found that the mix according to the invention of Example 2 leads to higher levels of expulsion of the aqueous phase and higher final compactness values than those of the mix without a nonionic surfactant, but these are, however, lower than those of the mix according to the invention described in Example 1.

It should be pointed out that the water expulsion is much more rapid in the case of the mix containing a nonionic surfactant than in the case of a mix not containing a nonionic surfactant but that the breaking kinetics of the 2 emulsions are similar.

Example 3 (cold open-graded mix) A cold open-graded mix is prepared according to the operating method described above, with the same aggregate as that used for preparing the mixes of Examples 1 and 2 and used in the same proportions as in the previous examples; the added-water content of the mix is identical to those of the mixes of Examples 1 and 2.

According to the method described in European patent specification EP 589,740, a hybrid emulsion is prepared whose residual binder penetrability is equal to 70, containing 61% by volume of bitumens and obtained by mixing 60 parts by weight -19of a 1st emulsion containing 61% by volume of a 20/30 penetrability bitumen and parts by weight of a 2nd emulsion containing 61% by volume of a 300/400 penetrability bitumen, the 2 bitumens being sold by Elf, the 1st and the 2nd emulsions each containing 6 kg of POLYRAM® SL (acidified with hydrochloric acid so that the pH of the soap is 2) per 1000 kg of water bitumen.

Once the hybrid emulsion has been manufactured from the 2 emulsions described above, a nonionic surfactant is added to it, this being an alcohol based on a fatty chain containing 10 carbon atoms, NACOL®, with 4 mol of ethylene oxide per mole of alcohol, called hereafter NACOL® 4 OE in an amount of 1.8 kg of nonionic 10 surfactant per 1000 kg of water bitumen cationic surfactant acid. Under the operating conditions explained above, a mix based on this hybrid emulsion is manufactured and then compacted. The bitumen content is 6 g per 100 g of aggregate.

By way of comparison and under the same operating conditions, a mix obtained from an emulsion to which no nonionic surfactant was added is prepared and 15 compacted.

The compacting results are given in Table 3, the porosity and the water expulsion being calculated at the end of the compacting after 30 gyrations.

Table 3 ••:Table 3 Type of mix Test No. Porosity Expelled water Open-graded mix 3 1 17.7 15.2 without nonionic 3 2 18.05 12.7 surfactant 3 3 18 14 Average 17.9 14 Open-graded mix 3 -4 17.1 18.3 according to the 3 5 17.4 18.4 invention 3-6 17.2 17.7 Average 17.2 18.1 The expulsion of the aqueous phase and the compactness are improved in the presence of the nonionic surfactant; it should be pointed out that the water expulsion occurs on average after 4 gyrations, whereas, for the mix not containing nonionic surfactant, expulsion occurs on average only after 26 gyrations, but that the breaking kinetics of the 2 emulsions are similar.

Example 4 (cold semidense-graded-to-dense-graded mix) A cold semidense-graded-to-dense-graded mix is prepared according to the operating method explained in Example 3.

The aggregate used, granitic in nature, has the following particle size 10 distribution: 0/2 mm 39% 6/10 mm 61% and its filler content is about The amount of water added is 6 g per 100 g of aggregate.

15 A hybrid emulsion with a residual binder penetrability of 80 is prepared, this emulsion containing 63% by volume of bitumens and being obtained by mixing 60 parts by weight of a 1st emulsion containing 63% by volume of a 20/30 penetrability bitumen and 40 parts by weight of a 2nd emulsion containing 63% by volume of a 500 penetrability bitumen, the 2 bitumens being sold by Elf, the 1st and the 2nd emulsions t*o 20 each containing 6 kg of POLYRAM® SL (acidified with phosphoric acid so that the pH of the soap is 2) per 1000 kg of water bitumen. The bitumen content is 5.7 g per 100 g of aggregate.

By way of comparison, a mix based on this hybrid emulsion, aggregate and added water is prepared and compacted.

Using this hybrid emulsion, 3 hybrid emulsions are prepared by adding in the case of the 1st emulsion, NACOL® 4 OE in an amount of 1.85 kg per 1000 kg of water bitumen cationic surfactant acid (emulsion according to the invention), in the case of the 2nd emulsion, an alcohol based on a fatty chain containing 0*

S.

S t@ S. *S

S

carbon atoms, NACOL®, with 12 mol of ethylene oxide per mole of alcohol, called hereafter NACOL® 12 OE, in an amount of 1.85 kg per 1000 kg of water bitumen cationic surfactant acid, in the case of the 3rd emulsion, an alcohol based on an essentially oleic fatty chain, ROFANOL® 70/75, in an amount of 2 kg per 1000 kg of water bitumen cationic surfactant acid (the emulsion according to the invention).

Three mixes each based on these 3 emulsions, aggregate and added water in the proportions indicated above were then prepared and compacted. The results are given in Table 4. The porosity and the water expulsion arecalculated at the end of the 10 compacting after 120 gyrations.

Table 4 Type of mix Test No. Porosity Expelled water Semidense-graded mix 4 1 11.15 53.7 without nonionic 4-2 10.7 54.6 surfactant 4-3 11.6 50.4 Average 11.2 52.9 Semidense-graded mix 4 4 9.8 62.5 20 with NACOL 4 OE according 4-5 9.63 63.5 to the invention 4 6 10.4 61.75 Average 9.9 62.6 Semidense-graded mix 4- 7 10.9 49.6 4-8 11.4 53.1 with NACOL 4 OE 4-9 11.1 52.6 Average 11.1 51.8 Dense-graded mix 4 10 9.1 65.3 according to the 4 11 9.2 67.6 invention with 4 12 8.9 66.8 ROFANOL® 70/75 Average 9.1 66.6 55555

S

0 -22- It is found that the compactness and the water expulsion obtained by compacting the mix according to the invention prepared from the emulsion containing the NACOL® 4 OE nonionic surfactant and from the emulsion containing the ROFANOL® 70/75 surfactant are greater than those obtained by compacting the mix prepared from the emulsion containing the NACOL® 12 OE nonionic surfactant or the mix prepared from the hybrid emulsion not containing any nonionic surfactant.

Furthermore, it should be pointed out that the rate of breaking of the emulsion containing the NACOL® 12 QE is slower than that of the emulsion containing the NACOL® 4 OE (in the same proportions) and than that not containing any nonionic surfactant. The 10 breaking kinetics of the emulsion with ROFANOL® 70/75 differs little from those of the reference emulsion.

When another mix based on a hybrid emulsion containing NACOL® 12 OE, which is distinguished from the emulsion containing NACOL® 12 OE described above in that it contains 0.5 kg of NACOL® 12 OE per 1000 kg of water bitumen cationic emulsifier acid instead of 1.85 kg, is prepared and compacted, it is noted that this emulsion breaks more rapidly than the emulsion containing almost 3 times as much nonionic surfactant but still breaks more slowly than the emulsion without nonionic surfactant. In addition, if a mix based on a hybrid emulsion containing 0.5 kg of NACOL® 12 OE per 1000 kg of added water bitumen cationic emulsifier acid is prepared and compacted, it is found that the compactness and the water expulsion remain at the level of the control without nonionic surfactant.

Example 5 (cold open-graded mix) The aggregate used is identical to that of Example 1.

The aggregate, bitumen and added-water contents are identical to those of Example 1.

The emulsion contains: 60% by volume of the bitumen described in Example 1; 6 kg of POLYRAM® SL (acidified with hyfrochloric acid so that the pH of -23the soap is 2) per 1000 kg of water bitumen; 3 kg of ROFANOL® per 1000 kg of water bitumen cationic emulsifier acid.

A mix according to the invention based on the emulsion, aggregate and added water described above and, by way of comparison, a mix based on an emulsion without nonionic surfactant are prepared and compacted.

The results are given in Table Table Type of mix Test No. Porosity Expelled water Open-graded mix 5 1 17.5 22.8 without nonionic 5 -2 16.9 23.2 surfactant 5-3 17.1 23 15 Average 17.2 23 Open-graded mix 5-4 16 30.7 according to the 5-5 15.8 30.9 invention 5-6 16.1 30.5 Average 16 30.7 It is found that the compactness and the expulsion of the aqueous phase are improved for the compacted mix according to the invention compared with the compacted mix not containing any nonionic surfactant.

Expulsion of the fluid occurs earlier in the case of the compacted mix according to the invention than in the case of the compacted mix not containing any nonionic surfactant: on average, after 5 gyrations instead of 22 gyrations. The breaking kinetics of the 2 emulsions are similar.

Example 6 (cold open-graded mix) Here, the compacting of the mix prepared with the emulsion without nonionic -24surfactant of Example 5 is compared with that of a mix prepared from the same proportions of an emulsion which is distinguished from that without nonionic surfactant of Example in that it contains 5 kg of POLYRAM® SL instead of 6 kg, from the same aggregate and from water added beforehand with, per 100 parts by weight of water, 0.37 parts by weight of POLYRAM® SL (cationic emulsifier), 0.37 parts by weight of ROFANOL®, and hydrochloric acid in an amount such that the pH of the added aqueous solution is equal to 5. The aggregate,,bitumen and added-aqueous-solution contents are identical to those of Example 1.

10 The results are combined in Table 6.

*Table 6 Table 6 15 Type of mix Test No. Porosity Expelled water Mix without nonionic 1 17 22 surfactant Mix according to the 1 15.9 25.6 invention The porosity and the water expulsion are calculated at the end of the compacting after 30 gyrations: it is found that the water expulsion and the compactness of the mix according to the invention are superior to those of the mix not containing any nonionic surfactant.

The fluid is expelled earlier in the case of the compacted mix according to the invention than for the compacted mix without nonionic surfactant: on average, after gyrations instead of 22 gyrations. The breaking kinetics are similar.

Example 7 (cold poured mix) A cold poured mix is prepared according to the operating method described above.

The aggregate used is microdiorite, the particle size distribution of which is as follows: 0/2 mm 2/6 mm which falls within a Type III ISSA grading range and has a filler content of 10% by weight.

The added-water content is 10 g of water per 100 g of aggregate.

The bituminous emulsion according to the invention contains: S- 61% of 70/100 penetrability Via Total bitumen; 10 10 kg ofPOLYRAM® S (acidified with hydrochloric acid so that the pH ofthe soap is 2) per 1000 kg of water bitumen, these being mixed with 2.5 kg of ROFANOL® per 1000 kg of water bitumen cationic emulsifier acid. The bitumen content is 7 g per 100 g of aggregate.

By way of comparison, an emulsion is prepared which is distinguished from the previous one in that it does not contain any nonionic surfactant.

The aggregate wetted with the added water is mixed with one or other of the above emulsions using a spatula in a kettle until the emulsion breaks.

It is found that breaking occurs sooner for the mix prepared from the emulsion according to the invention (1 min 40 s) than for that prepared from the emulsion according to the prior art (2 min 10 s).

Two mixes based on the same ingredients, used in the same proportions, are prepared in a kettle; manual mixing is stopped just before the emulsion breaks and the kettle is tilted and the time taken for the first drop of breaking water to appear below the mass of mix is measured.

In the case of the mix according to the invention, the first drop of breaking water appears after 2 minutes, whereas it appears after 4 minutes for the mix according to the prior art.

In the case of the 2 mixes tested, the amounts of breaking water are comparable.

Example 8 (surface coating) A bituminous emulsion is prepared which contains: 69% by volume of an 180/220 penetrability Elf bitumen sold by the company; 3 kg ofa cationic emulsifier sold underthe brand name DINORAM® S per 1000 kg of water bitumen. The breaking index of this emulsion is equal to 100 and its viscosity equal to 6 which is considered as too low a viscosity in the case in question. The D-S difference, equal to the difference in water concentration of the emulsion between top and bottom of the storage container, and which represents the storage sensitivity according to the ASTM D 244-89 test, is 4% of water at 7 days.

10 Based on the same ingredients, a more viscous emulsion, containing the same i proportion of bitumen but containing 4.5 kg ofDINORAM® S and 2 kg ofROFANOL® per o* 1000 kg of water bitumen cationic emulsifier acid, is prepared. The breaking index of this emulsion is equal to 90 and its viscosity equal to 12 OE, the D-S difference being 1% of water at 7 days.

Example 9 (cold open-graded mix) The aggregate used is identical to that of Example 1.

The emulsion contains 60% by volume of the bitumen described in Example 1, 6 kg of POLYRAM® SL (acidified with hydrochloric acid so that the pH of the soap is 2) per 1000 kg of water bitumen, 0.3 kg ofFORAFAC 111 OD® sold by Atofina (a nonionic surfactant based on a perfluoroalkyl chain containing 8 carbon atoms, with 10 ethylene oxide units) per 1000 kg of water bitumen cationic emulsifier acid.

A mix according to the invention, using the emulsion, the aggregate and the added water which are described above, and, by way of comparison, a mix using an emulsion without a nonionic surfactant are prepared and compacted.

.'7

C

-27- The results are given in Table 7.

Table 7 Type of mix Test No. Porosity Expelled water Open-graded mix 1 1 17.3 without 1-2 17.7 17 nonionic 1-3 17.4 18.4 surfactant 'Average 17.5 16.8 Open-graded 9-4 16.5 22.2 mix 9-5 16.3 21 according 9 6 16.7 24.3 to the Average 16.5 22.5 invention

Claims

1. A bituminous emulsion comprising at least one bituminous binder, water and at least one cationic, anionic or nonionic emulsifier, characterized in that it comprises at least one surfactant additive which is: a) a polyethoxylated nonionic surfactant of formula: Rx[O(C 2 H 4 )]yOH or RxCO[O(C 2 H 4 )]yOH where Rx represents a substituted or unsubstituted, saturated or unsaturated, linear or branched carbon chain, or an alkyl(ene)phenyl, or one of the above chains in which the hydrogen is partly or completely substituted with fluorine; 10 x represents the number of carbon atoms of the carbon chain or of the alkyl(ene)phenyl; Sy represents the number of ethylene oxide units; 7 x 22 and 0 y 8 for surfactants corresponding to the first formula; and 7 x 22 and 2 y 8 for surfactants corresponding to the second formula; b) a polyethoxylated nonionic surfactant of formula: .Rx[O(C2H4)]yOH or RxCO[O(C 2 H4)]yOH where Rx represents a linear or branched poly(dimethylsiloxane) chain; x represents the number of silicon atoms; y represents the number of ethylene oxide units; and 4 x 15 and 4 y c) an amphoteric surfactant of formula: Rx[N'(CH 3 2 (CH 2 )yA, RNH(CH 2 )yCOOH or RNH(CH 2 )yB,C where Rx is as defined in a); A represents COO-, OSO 3 or OSO2; B represents OSO 3 or OSO2; C represents the cationic counterion of an alkali metal or alkaline earth metal, iron, copper, manganese or zinc, or the ammonium cation, in a proportion such that the salt is electrically neutral, y represents the number of CH 2 units; and -29- 7 x s 22 and 0 y 4; d) an amphoteric surfactant of formula: Rx.[N(CH 3 2 ](CH 2 )yA, RIxNH(CH 2 )yCOOH or R,NH(CH 2 )yB,C where Rx is as defined in b); A, B, C and y are as defined in and 4 x 15 and 0 y 4; e) an alkanolamide surfactant of formula: RxCONH(CH 2 )yOH or RxCON[(CH 2 )yOH] [(CH 2 )zOH] where Rx is as defined in a); 10 y and z represent the number of CH 2 units; and 7 x 22, 1 y 4 and 1 g z 4; or f) an amide-oxide surfactant of formula: Rx(CH 3 2 NO where Rx is as defined in and 7 x 22.

2. An emulsion according to claim 1, in which y 6 in the polyethoxylated nonionic surfactant a) corresponding to the first formula.

3. An emulsion according to claim 1 or 2, in which y 6 in the polyethoxylated nonionic surfactant a) corresponding to the second formula.

4. An emulsion according to any one of the preceding claims in which the concentration of surfactant additive is between 0.2 kg and 8 kg per tonne of emulsion. An emulsion according to any one of the preceding claims which is cationic and comprises at least one cationic emulsifier which is an alkyl(ene) polyamine, alkoxylated alkyl(ene) polyamine, quaternary alkylammonium salt or alkyl(ene)amidoamine or an alkylimidazoline cyclization derivative thereof, having an alk(en)yl chain comprising between 8 and 22 carbon atoms.

6. An emulsion according to claim 5 comprising at least one acid.

7. An emulsion according to any one of claims 1 to 4 which is anionic and comprises at least one anionic emulsifier which is an alkyl(ene)carboxylate, alkyl(ene)sulphate, alkyl(ene)sulphonate, alkyl(ene)aryl(ene)carboxylate, alkyl(ene)aryl(ene)sulphate, alkyl(ene)aryl(ene)sulphonate or alkyl(ene)(aryl(ene)) phosphoric ester, having an alk(en)yl or alkyl(ene)(aryl(ene)) chain comprising between 8 and 22 carbon atoms.

8. An emulsion according to claim 7 comprising at least one base.

9. An emulsion according to any one of claims 1 to 4 which is nonionic and comprises at least one nonionic emulsifier which is an alkyl(ene)poly(oxyethylene) alcohol or alkyl(ene)aryl(ene)poly(oxyethylene) alcohol, having an alk(en)yl chain comprising between 8 and 22 carbon atoms and at least 9 ethylene oxide units. 10 10. An emulsion according to claim 1 substantially as hereinbefore described.

11. An emulsion according to claim 1 substantially as described in the Examples.

12. A process for preparing a bituminous emulsion as defined in any one of claims 1 to 11, which process comprises mixing a surfactant additive with a cationic, anionic or nonionic emulsifier before the manufacture of the emulsifying or dispersed phase, either in the emulsifying phase before the manufacture of the emulsion or in the emulsion at any time between the end of emulsification of the emulsion and its use.

13. A material obtainable by coating or contacting a) an aggregate or road support with a bituminous emulsion as defined in any one of claims 1 to 11, and/or b) an aggregate wetted with water or an aqueous solution comprising at least one surfactant additive as defined in any one of claims 1 to 3, with a bituminous emulsion as defined in any one of claims 1 to 11.

14. A material according to claim 13, in which the aqueous solution comprising at least one surfactant further comprises at least one cationic or anionic surfactant. A material obtainable by coating or contacting an aggregate wetted with an aqueous solution comprising at least one surfactant additive as defined in any one of claims 1 to 3, with a bituminous emulsion with does not contain a surfactant additive as I 31 defined in any one of claims 1 to 3.

16. A material according to any one of claims 13 to 15, which is of the cold-cast mix type.

17. A material according to any one of claims 13 to 15, which is of the open-graded S mix. semidense-graded mix, dense-graded mix, storage-grade mix or emulsion-stabilised gravel type.

18. A road pavement obtainable by compacting a material as defined in any one of claims 13 to 18.

19. A material according to any one of claims 13 to 15 of the surface-coating and Il road-pavement type, obtainable by successive application of one or more bituminous emulsion coats and of one or more aggregate courses on a road support.

20. A material according to any one of claims 13 to 15 of the bond-coat type.

21. A material according to claim 20 obtainable by spraying a bituminous emulsion on a road support. 2. A material according to claim 13 or 15 substantially as hereinbefore described.

23. A material according to claim 13 or 15 substantially as described in the 9 examples.

24. The product of the process of claim 12. Dated 31 May, 2000 20 CECA S.A. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 9 I1 111111SS3 loc HAV