WO2002000795A2 - Method for preparing cold bituminous mixes and road pavements from bituminous emulsions, said bituminous emulsions - Google Patents

Abstract

The invention concerns a method for preparing cold bituminous mixes and road pavements for enhancing mix compaction and for draining demulsification water. Said method is particularly adapted to renovation or repair works on existing road surfaces which need to be reopened to traffic very quickly. The invention also concerns bituminous emulsions, which, when used according to the inventive method, enable to obtain mixes whereof the compacting and for draining demulsification water are particularly efficient.

Description

TECHNICAL FIELD The present invention relates to the manufacture of bituminous emulsions as well as of asphalt mixes and road carpets obtained. at room temperature (ie generally between 0 ° C and +40 ° C) from aggregates and these emulsions. PRIOR ART Bituminous emulsions in most cases comprise a bituminous binder, a cationic surfactant - we then speak of cationic emulsions -, or an anionic surfactant, - we then speak of anionic emulsions - or a nonionic surfactant - we speak then non-ionic emulsion - and water. Cationic emulsions are particularly prized, both for the speed of their rupture on the aggregates and for the qualities of adhesiveness which are generally obtained between the aggregates and the broken emulsion giving the road carpets which have just been produced, good mechanical properties. In addition to the components mentioned above, the cationic emulsions are often acidified by adding acid within the aqueous phase used for the manufacture of the emulsion and the anionic emulsions are generally produced in an alkaline medium. Cold mixes, bituminous materials obtained by coating or bringing aggregates into contact using bituminous emulsions at room temperature, have been known for a long time. The profession distinguishes in particular cold cast mixes (ECF), open cold mixes, semi-dense, dense, storable, serious emulsions, surface coatings and bonding layers. For the production of road carpet, ¹ type of bituminous material is constituted by the cold-poured coated; in this case, the installation problems are resolved in most cases if we follow the rules of the art: the mix is set up in the "soup" state a few seconds after being manufactured , and thus the passage of the asphalt under the sled table is not problematic and there is no problem of poor leveling of the final road carpet. On the other hand, we find the necessary step to increase in cohesion which is generally done without external solicitation by chemical and physical evolution of the system, although in in some cases compaction is carried out. This development involves the coalescence of the bitumen of the emulsion and is accompanied by a spontaneous departure from the aqueous phase. If the first phenomenon is fairly well controlled by a person skilled in the art who can control the formula of the emulsion, the nature and the amount of breaking additive, the control of the second phenomenon is still only partially resolved in best of all thanks to compaction, which can sometimes lead to insufficient cohesion at a young age.

The 2 ^nd type of bituminous materials includes open cold mixes, semi-dense, dense, storable cold mixes as well as grave-emulsions; the optimized choice of bituminous emulsion (nature and quantity of emulsifier, bitumen concentration, pH) according to the prior art makes it possible to solve, in the majority of cases, partially or totally, the problems of coating, transport and setting in place of the mix in its expanded form. Two additional steps are necessary to obtain a pavement: first the installation of the asphalt in the form of a carpet, then compaction, the role of which is to ensure the rise in cohesion, that is to say say good adhesion between bitumen and aggregates, necessary to allow the carpet to withstand road traffic.

In the case where the mix is spread by means of a grader, the shaping of the mix in expanded form is done only when the grader is unloaded. The carpet shaping step takes place in the case of the grader by passing the mix under the blade, the height of which is adjusted by the operator.

In the case where the asphalt is spread by means of a paver, the implementation in expanded form is carried out by unloading in the receiving hopper of the paver and conveying of the asphalt through a tunnel to a screw which distributes the mix over the desired width. The matting is carried out by a table making a defined angle with the support and thus delimiting a space with the support.

We note that, even in cases where the placement of the mix in its expanded form went well, the shaping of the mix in the form of a carpet by the machine (whether grader or finisher) can lead to segregation of the putty (generally consisting of mineral elements passing through a 2 mm square mesh sieve and mixed with the bitumen) from the the largest aggregates, segregation which is appreciated visually by the operator. This segregation is not only detrimental to the overall cohesion of the carpet because certain areas are depleted in mastic but is also detrimental to the surface uniformity given the compaction capacity of the areas rich in mastic greater than that of the areas poor in mastic. On the other hand, since cold mixes are very rubbing, passage through a confined space, in particular through a paver, is difficult, which makes it necessary to reduce the speed of advance of the paver or to increase the angle of attack with, in the latter case, a negative impact on the uni. In the case of a grader and a paver, too much internal friction in the asphalt (ie friction between the constituents of the asphalt) can prevent it from being placed in the form of a thin carpet and force it to deposit a greater asphalt thickness than initially planned. It is therefore advantageous to be able to limit the friction within the mix during the shaping of the carpet, while limiting the segregation. Cohesion is obtained by tightening the mix accompanied by the expulsion of an aqueous phase and air. As indicated above, cold-coated materials have a high friction power, which hinders tightening: the compactness obtained when cold is very often less than the compactness obtained from the same hot-coated material with the same binder. However, it is well known to those skilled in the art that the value of the compactness and the importance of the departure of water during compaction make it possible to judge the cohesion of the cold-pressed material. We also note that currently the success in the realization of pavements subjected to intense traffics (T1 or more) depends not only on the technical conditions in which the spreading, compaction or tightening of the asphalt takes place but also on weather conditions the day of the construction site or even the following day. A strong sun, a high temperature or a sufficient wind contribute to the drying of the carpet and its rise in cohesion. In all these cases of application of cold mixes considered here (poured, storable, open, semi-dense, dense and grave-emulsions), (re) quickly open to traffic which is a constraint imposed by the masters of work on the site, particularly in the case of repairing or renovating roadways, poses all the more problems since the road traffic to which the roadway is subject is intense. In the case of an early opening of the roadway to traffic, the film of water generally present between the largest aggregates and the binder layer prevents the creation of an adhesive contact binder aggregates: a departure of aggregates occurs, this which weakens the carpet vis-à-vis aggressions and simultaneously degrades its surface quality, that is to say its solid. Only drying by evaporation allows this aqueous film to disappear, once the (re) opening to traffic has been carried out. It is therefore advantageous to find a technical solution which makes it possible to eliminate the maximum amount of water from the mix during the installation period and / or during the road mat shaping period so as to improve the efficiency of the compacting the carpet in the shortest possible time.

STATEMENT OF THE INVENTION

The present invention provides a method of manufacturing cold mixes and road belts obtained from bituminous emulsions and aggregates which makes it possible for all types of mixes (types 1 and 2) to improve the compaction of the mix and drainage of break water, and for mixes of type 2 mix only, to optimize the effects on coarse aggregate / mastic segregation observed with the processes of the prior art and to reduce internal friction .

The process of the present invention is particularly advantageous, in particular in the case of renovation or repair of existing roadways, insofar as it makes it possible to obtain road carpets having a good level and which can be reopened very quickly to road traffic without 'It is necessary to wait several hours, even several days, for the evaporation of the residual aqueous phase not evacuated during the rupture of the emulsion and of the compaction. The rapid stabilization of the road belts thus obtained is of considerable economic interest.

The process for manufacturing cold mixes according to the invention from bituminous emulsion and aggregates is characterized in that, after destabilization of the emulsion and appearance of the water of rupture, the mix is subjected to a sufficient mechanical agitation for the foaming of the rupture water to be observed * at the latest after 1 min of mechanical agitation for cold mixes of type l,

^* at the latest after 3 min of mechanical stirring for cold mixes of type 2. To obtain the foaming of the water of rupture, it is therefore necessary to have accomplished the destabilization or rupture of the emulsion beforehand. The term “destabilization of the emulsion” is understood to mean a modification of the mechanical behavior of the system, once the emulsion has been added to the humidified aggregate, which results in an increase in torque during mechanical stirring at constant speed; the time at which the increase in torque is noted is called the destabilization time. The foaming of the rupture water causes a change in the mechanical behavior of the mix which becomes much more fluid and changes its visual appearance (the bubbles of the foam, the sizes of which are between approximately one tenth of a millimeter and the centimeter , bring a change of color). We can speak of transition in the properties of the mix. However, the inventors have found that in some cases, the two mechanical transitions caused by destabilization and foaming overlap and the mechanical behavior does not change significantly.

According to the invention, it is a question of foaming the rupture water after destabilization of the emulsion and not the emulsion optionally mixed with the addition water. To make the distinction in these difficult cases, we observe the color of the foam at the end of mixing, the duration of which is indicated above: if it is light in color, typically white or gray, it is a foaming of the water of rupture, therefore in accordance with the invention and the destabilization of the emulsion has taken place, if the foam is dark in color, typically brown, it is a foaming of non-destabilized emulsion and not in accordance with the invention.

In order to promote the foaming of the break water, it is also possible to formulate the bituminous emulsions used so as to use higher amounts of water than the amounts used by a person skilled in the art: in the case of coated with type 1, quantities of the order of 8 to 15 g of addition water will be used per 100 g of aggregates; in the case of asphalt mixes of type 2, quantities of addition water of the order of 5 to 10 g per 100 g of aggregates will be used. During the manufacture of type 1 mixes (ECF), the mixture is kneaded (emulsion + aggregates + added water) until the emulsion is destabilized and the mix is kneaded until appear bubbles made up of air and water of rupture and whose size is approximately between the tenth of a millimeter and the centimeter and which appear in the asphalt during its production in the mixer of the sled and under the table of the sled . According to this method, there is no evidence of solidification in the mixer of the sled of the ECF machine or under the sled table. Once the asphalt has been deposited in the form of a carpet, it is necessary to compact it using rubber or tire compactors. It is surprisingly found that the fluidity of the asphalt does not prevent compaction.

For the manufacture of type 2 mixes, a distinction is made between batch coating processes and continuous coating processes. In the case of a batch process, the foaming of the breaking water can be promoted by modifying the speed of rotation of the blades and the filling rate of the mixer. In the case of a continuous process, the foaming of the breaking water can be promoted by modifying the residence time of the mix in the mixer by varying the speed of rotation of the blades and their inclination and / or by optimizing the filling rate of the mixer, for example by varying the aggregate flow rates. The frothing of the break water can take place during the unloading of the mix.

At the same time for the asphalt mixes prepared continuously or discontinuously, the aim is to promote foaming as much as possible by adjusting the adjustment of the carpet shaping devices: for a grader, one can play on the angle of the blade and on the forward speed; for a paver, we can play on the speed of rotation of the screw, even feeding the table discontinuously so as to respect the consumption rates of the mix. By implementing the method according to the invention, the passage of the asphalt under the paver or under the grader is facilitated and the segregation limited compared to the methods of the prior art.

The present invention also relates to bituminous emulsions, which can be used for the production of cold mixes of types 1 and 2 and mixes and road carpets prepared according to the process of the invention detailed above; the cold mixes according to the invention surprisingly exhibit a particularly significant departure of water with compaction and therefore make it possible to obtain road belts whose compactness is greater than those of road belts prepared from other emulsions of the prior art, and this, without changing the operating conditions of the stages of manufacture of said bituminous emulsions, the storage of the mixes obtained from their mixture with aggregates and their possible transport, as well as their unloading.

In addition to the usual cationic, anionic or nonionic surfactant emulsifier (s), bituminous binder and water, the emulsions according to the invention comprise at least one additive A and to the minus one additive B. These additives A and B can be mixed with the cationic, anionic or nonionic emulsifier (s) before the emulsifier phase is produced, or else dispersed, either in the emulsifying phase as manufactured according to the state of the art using cationic, anionic or nonionic emulsifiers before the manufacture of the emulsion, that is to say in the emulsion manufactured according to the rules of the art to using cationic, anionic or nonionic emulsifiers, at any stage between the end of the emulsification and the use of the emulsion. The addition of additives A and B making it possible to lather the water of rupture could also have the consequence of lathering the emulsion during the incorporation of these additives into the emulsion. However, it is surprisingly found that this is not the case: the additives A and B do not give a more foaming character to the emulsion than that sometimes found on the surface of the bituminous emulsions of the prior art.

In order to promote the foaming of the breaking water, it is possible to promote the foaming of the emulsion during its spraying on the aggregates moistened in the kneading apparatus by using suitable spray nozzles such as nozzles with air entrainment. But it is surprising to note that the foaming alone of the emulsion is not a sufficient condition for obtaining an improvement in the application properties of the mixes detailed above: it is also necessary to have a foaming of the water of rupture such as previously defined.

It is possible to add the water used to humidify the aggregates using the additives A and B. In this case, to facilitate the dispersion, it is advantageously possible to additivate the water using a nonionic emulsifier and it is possible to place in an acid medium in the presence of a cationic emulsifier or in medium basic in the presence of an anionic emulsifier. In order to promote the foaming of the breaking water, it is possible to promote the foaming of the addition water during its spraying on the aggregates by using suitable spray nozzles, such as nozzles with drive of air. It is also possible to incorporate part of the additives A and B into the emulsion and the rest in the addition water used to moisten the aggregates. These additives A and B can be surfactants. In the present text, a distinction is made between the term "emulsifier" and the term "surfactant": the two terms correspond to products exhibiting interfacial physical activity such as the reduction of surface tension, but the emulsifier is a chemical which allows (in the sense of the prior art) to put a bituminous binder in emulsion, while the surfactant of bituminous emulsions according to the present invention called additive A is an organic product which, in association with another additive, surfactant or non-surfactant called additive B allows the foaming of the breaking water when the process according to the invention is used to manufacture cold mixes and road carpets.

The additive A used in the emulsions according to the invention can in particular be chosen from

A1- polyoxyethylated nonionic surfactants, alone or in mixture, of raw chemical formulas:

R _x [0 (C ₂ H ₄ )] y OH or R _x CO [0 (C ₂ H ₄ )] _y OH where R _x represents either a linear or branched carbon chain, saturated or not, substituted or not, or a alkyl (ene) phenyl, or one of the preceding chains for which hydrogen is partially or totally substituted by fluorine, x represents the number of carbon atoms of the carbon chain or of alkyl (ene) phenyl, y represents the number of ethylene oxide units, with 7 ≤ x ≤ 22, O≤ y ≤ 8 and preferably y ≤ 6 for the molecules corresponding to the first crude formula with 7 sx ≤ 22, 2 ≤ y <8 and preferably y ≤ 6 for molecules corresponding to the second raw formula.

The preferred surfactants A1 are chosen from polyoxyethylated alkyl (ene) ether for which 7 ≤ x ≤22, polyoxyethylated alkyl (ene) ester for which 7 ≤ x ≤22, polyoxyethylated alkyl (ene) phenol for which 7 ≤ x ≤ 22, alone or mixed

A2- polyoxyethylated nonionic surfactants, alone or in mixture, of raw chemical formulas:

Rx [0 (C ₂ H ₄ )] _y OH or R _x CO [0 (C ₂ H ₄ )] _y OH where R _x represents a linear or branched poly (dimethylsiloxane) chain where x represents the number of silicon atoms , y represents the number of ethylene oxide units, with 4 ≤ x <15, 4 ≤ y ≤ 20

A3- amphoteric surfactants, alone or in mixture, of raw chemical formulas:

R _x [N ⁺ (CH ₃ ) ₂ ] (CH ₂ ) _y A or RχNH (CH ₂ ) _y COOH or R _x NH (CH ₂ ) _y B, C where R _x represents the same chains as in A1

A represents the group COO ^~ , the group OS0 ₃ ^~ out the group OSO2 ^"- , B represents the group OS0 ₃ ^- or the group OS0 ₂ ^{" ~} ,

C represents either the counter-cation of alkali or alkaline-earth metal, iron, copper, manganese, zinc, or the ammonium cation, in proportion such that the salt is electrically neutral there represents the number of CH _{2 units} , with 7≤ x ≤ 22, O≤ y ≤ 4.

A4- amphoteric surfactants, alone or in mixture, of raw chemical formulas:

R _x [N ⁺ (CH ₃ ) ₂ ] (CH ₂ ) _y A or R _x NH (CH ₂ ) _y COOH or R _x NH (CH ₂ ) _y B, C where R _x represents the same chains as in A2 A represents the same groupings as in A3

B represents the same groups as in A3 C represents the same cations as in A3, in proportion such that the salt is electrically neutral y represents the number of CH ₂ patterns,

A 5- the alkanolamide surfactants, alone or as a mixture, of crude formula: R _x CONH [(CH ₂ ) _y OH] or R _x CON [(CH ₂ ) _y OH] [(CH ₂ ) ₂ OH] where R _x represents the same strings as in A1 with 7 ≤x ≤ 22, 1 ≤ y ≤ 4, 1 ≤ z ≤ 4

où R_x représente les mêmes chaînes qu'en A1 avec 7<x ≤ 22A6- amine oxide surfactants, alone or as a mixture, of crude formula:

where R _x represents the same chains as in A1 with 7 <x ≤ 22

The concentration of additive (A) in emulsions according to the invention is generally not less than 0.2 kg per tonne of emulsion and is generally not more than 8 kg per tonne of emulsion. The extent of the additive additive (s) A is appreciated in relation to the concentration of cationic, anionic or nonionic emulsifier used by those skilled in the art. Generally, this concentration does not exceed the concentration of cationic, anionic or nonionic emulsifier of the emulsion. The chemical nature and the quantity of additive (s) A making it possible to optimize the application properties stated above depend on the aggregate used for bituminous materials of type 1 and 2. The additive B used in the emulsions according to l The invention can be chosen in particular from:

B1- the salts, alone or in mixture, of raw chemical formula: NH ₄ X where X corresponds to a halogen element B2- the salts, alone or in mixture, of raw chemical formula:

Tu NH ₄ Y where T _u represents a linear or branched carbon chain, saturated or not, substituted or not, u represents the number of carbon atoms in the carbon chain, Y corresponds to a halogen element with 1 ≤ u ≤ 6

B3- the salts, alone or in mixture, of crude chemical formula Tu NH ₄ Y where T _u represents an alkyl (ene) phenyl, u represents the number of carbon atoms in the alkyl (ene) phenyl, Y corresponds to a halogen element with 1 ≤ u ≤ 12

B4- the alkyl (ene) polyamines and more particularly the alkyl (ene) propylene diamines, the a! Kyl (ene) dipropylene triamines and the akyl (ene) tripropylene tetramines in which the alkyl (ene) chain has between 1 and 12 atoms of carbon. The concentration of additive (s) B in the emulsions according to the invention is generally not less than 0.1 kg per tonne of emulsion and is generally not more than 5 kg per tonne of emulsion. It can be added as is in the emulsifying phase or the emulsion, or dissolve them beforehand in water and add the solution to the emulsion. The chemical nature and the quantity of additive (s) B making it possible to optimize the application properties stated above depend on the aggregate used for bituminous materials of type 1 and 2.

Among the cationic emulsifiers which can be used for the manufacture of cationic emulsions and bituminous materials according to the invention, mention may be made of the usual cationic emulsifiers and in particular: • alkyl (ene) polyamines, and more particularly tallow

(poly) propylene polyamines such as tallow propylene diamine (EINECS definition: amines, N-tallow alkyltrimethylenedi-, RN = 61791-55-7) represented industrially by Dinoram® S from CECA SA, tallow dipropylene triamine (amines, N- tallow alkyldipropylenetri-, RN = 61791-57-9), tallow tripropylene tetramine (amines, N-tallow alkyltripropylenetetra-, RN = 68911-79-5) the latter being industrially well represented by the Polyram® S of CECA SA,

• alky (ene) oxyalkylated polyamines and more particularly tallow dipropylene triamine oxypropylated (amino, N-tallow propanol-2 [[[(3-amino propyl) amino] -3 propyl] imino] -1, 1'bis, RN = 97592-79-5) the latter being industrially well represented by the Polyram® SL of CECA SA,

• quaternary ammonium salts such as tallow propylene diamine quaternized with methyl chloride (composed of the quaternary ammonium ion, pentamethylsuif alkyltriméthylènedi-, chloride, RN = 68607-29-4) well represented for example by Stabiram® MS3 from CECA SA,

• alkyl (ene) amidoamines and more precisely ^' tallow or taloil (ene) alkyl amineamines, their alkylimidazoline cyclization derivatives, or mixtures thereof (condensation products of C ₈ -C ₂₂ fatty acids with polyalkylenes C ₂ -C3 polyamines and with ethanolamines, their mixtures and cyclization products of the amides obtained), well represented by the emulsifier Emulsamine® L60 from CECA SA; alkyl (ene) amidoamines are more especially used in the prior art for the production of bituminous emulsions for surface coatings and bonding layers.

The concentration of cationic emulsifier (s) of the emulsions according to the invention is generally not less than 0.8 kg per tonne of emulsion and is generally not more than 30 kg per tonne of emulsion . It is most often preferred to add to the aqueous phases emulsifier (s) surfactant (s) cationic (s) a certain amount of acid. In all cases, it is sought to have a total coating during the mixing, before the emulsion is destabilized.

In the case where bituminous emulsions based on alkyl (ene) amidoamine (s), such as for example Emulsamine® L60 and Emulsamine® LZ, are used for the manufacture of mixes according to the process of the present invention , we will use either amounts of emulsifier (s) greater than the amounts used for bituminous emulsions for surface coating and / or bonding layer of the prior art while retaining the pH usually used by those skilled in the art , typically close to 2, either the usual quantities used for bituminous emulsions for surface coating and / or bonding layer of the prior art will be used, but a surfactant such as a salt will be added to the addition water. quaternary ammonium such as Stabiram® MS3 from Ceca SA in sufficient quantity to ensure total coating before destabilization of the emulsion.

The anionic emulsifiers which can be used for the manufacture of anionic emulsions and bituminous materials according to the invention can be chosen from the usual surface-active anionic emulsifiers and in particular the alkyl (ene) carboxylates, alky (ene) sulfates and alkyl (ene) sulfonates, alkyl (en) aryl (en) carboxylates, alkyl (en) aryl (en) sulfates and alkyl (en) aryl (en) sulfonates as well as alkyl (en) (aryl (en)) esterphosphoric with an alk (en) chain yl or alkyl (ene) (aryl (ene)) comprising between 8 and 22 carbon atoms. It is most often preferred to add to the aqueous phases of anionic surfactant emulsifier (s) a certain amount of base. The concentration of anionic emulsifier (s) of the emulsions according to the invention is generally not less than 0.8 kg per tonne of emulsion and is generally not more than 30 kg per tonne of emulsion . The concentration of anionic emulsifier (s) used also depends on the type of bituminous material that one wants to manufacture.

The nonionic emulsifiers which can be used in the manufacture of nonionic emulsions and bituminous materials according to the invention can be chosen from the usual nonionic emulsifiers and in particular alkyl (ene) poly (oxyethylene) alcohols, alkyl (ene ) aryl (ene) poly (oxyethyiene) 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. The concentration of emulsifier (s) not -ionic (s) of the emulsions according to the invention is generally not less than 0.8 kg per tonne of emulsion and is generally not more than 20 kg per tonne of emulsion. The concentration of non-ionic emulsifier (s) used also depends on the type of bituminous material that one wants to manufacture.

The bituminous binders used can be chosen from the bituminous binders usually used in bituminous emulsions for materials of type 1 and 2; their penetrability is generally between 20/30 and 500. The emulsions can be prepared with one or more binders; in the latter case, either the various binders are mixed hot before the emulsification, or two (or more) emulsions are prepared, each containing a binder which will then be mixed to give a so-called mixed emulsion which will be brought into contact with the aggregates for the production of asphalt. An example of preparation of mixed bituminous emulsion is detailed in patent EP 589,740 B1 in the name of the applicant, the content of which is incorporated by reference; this patent describes mixed emulsions, one based on soft bituminous binder and the other based on hard bituminous binder to improve the workability of the mix while maintaining a good mechanical resistance of the final road belt.

The process according to the invention is particularly well suited ^" for producing asphalt mixes and road carpets of type 1 and 2 obtained from bituminous emulsions according to the invention described above, but it is also well suited for cationic bituminous emulsions, anionic or non-ionic containing at least one additive A within the meaning of the present invention but not containing additive B for mixes of types 1 and 2 as well as for cationic emulsions containing at least one alkyl (ene) amidoamine.

An additional advantage of the process according to the invention is that thanks to the foaming of the breaking water, the drainage of the water is better visualized by its ascent to the surface in the form of foam and it is thus possible to qualitatively assess the level of compaction: it it is thus possible to identify poorly compacted areas and complete the compaction so as to have a rise in breaking water in the form of foam distributed homogeneously over the entire surface of the carpet.

EXAMPLES Preparation of bituminous emulsions

In all of the examples which follow, the additives A and B are added to a cationic emulsion already prepared from a mixture of cationic emulsifier, acid, bituminous binder and water and the bitumen concentration of which is 65 % in volume. The addition of additives A and B is carried out during the hour preceding the use of the emulsion and the latter is stirred manually so as to distribute the additives homogeneously in the emulsion.

Asphalt manufacturing process

All asphalt and road carpet manufacturing tests are carried out at a temperature between 20 and 25 ° C. Several types of tests are implemented, each with its own protocol detailed below. Some stages of the tests use hand mixing, others use automated mixing. In the in the case of manual mixing, the speed of rotation is between approximately 3 and 5 rev / s (unless otherwise indicated), which corresponds to a higher speed than the usual manual mixing speeds during the manufacture of mixes.

In Examples 1, 2 and 3, the additives can lead to a modification of the reactivity of the emulsion. With certain additives, the concentration of cationic emulsifier has therefore been modified, so as to maintain destabilization kinetics close to those of non-additive emulsions. The term “kinetics of destabilization” is understood to mean kinetics such that the destabilization or rupture of emulsion judged visually takes place over periods of time not differing by more than '25%.

Example 1

Several emulsions are prepared and used, each containing a different additive A, then these emulsions are used to produce a mix and a road mat (type 2 wearing course) and show the influence of the nature of the additive on foaming behavior. .

To study the behavior of emulsions when foaming, approximately 500 g of aggregates are placed in a bowl, then the addition water is added and the mixture is kneaded manually for 30 s. The emulsion is then added and the mix is kneaded for 30 s. It is then stored in the bowl for 1 hour before mixing again (called remixing), after disintegration by hand if there is a solidification of the mix. It is remixed for a maximum time of 10 min and the duration after which the foam appears is noted. Asphalt preparation The bituminous emulsion (1.1) contains:

^* 65% by volume of a 70 penetration bitumen marketed by the company Elf,

* 6 kg of cationic emulsifier (Polyram® SL acidified with phosphoric acid so that the pH of the soap is 2), for 1 t of water + bitumen.

Aggregates: Thiviers Granulometry: 0/2 mm: 40%; 2/6 mm: 12%; 6/10 mm: 48%

Content of fillers (aggregates particles passing through an 80 μm sieve): of the order of 8% by weight. The addition water content in the mix is 7 g per 100 g of dry aggregates. The bitumen content is 6 g per 100 g of dry aggregates. A destabilization time of 40 s is obtained.

A bituminous emulsion (1.2) is made similar to the emulsion (1.1), except that it contains 7 kg of emulsifier (instead of 6 kg) for 1 t of water + bitumen, and which is added as additive A of Forafac® 1157 (amphoteric surfactant: betaine on a perfluorinated fatty chain of 8 carbon atoms in solution in water at 28% by mass) in proportion of 1 kg per 1 t of water + bitumen + cationic surfactant + acid ; the same destabilization time is kept as with emulsion 1.1 and a significant foaming is obtained in all of the mix after 30 s of remixing.

We make a bituminous emulsion (1.3) similar to emulsion 1.1, except that it contains 7 kg of emulsifier (instead of 6 kg) for 1 t of water + bitumen, and that we add as additive A Nacol® 10 at a rate of 1 kg of fatty alcohol (alcohol on fatty chain of 10 carbon atoms) for 1 t of water + bitumen + cationic surfactant + acid; foaming is obtained after 20 s of remixing. However, the foam is not present in all of the mix, but only in the mastic, which leads to a fluidity (appreciated visually) lower than that obtained with Forafac® 1157.

The nature of the additive A therefore influences the foaming of the breaking water.

Example 2

Two emulsions for surface coatings are prepared and used which do not contain additive B but only contain additive A, the behavior of which is compared to foaming. Bituminous emulsions contain:

* 65% by volume of a 70 penetration bitumen marketed by the company Elf,

* 2.5 kg of cationic emulsifier (Emulsamine® L60 acidified with hydrochloric acid so that the pH of the soap is 2) for 1 t of water + bitumen. In emulsion 2.1 there is no additive A. In emulsion 2.2, Forafac® 1157 (28% active ingredient) is added up to 1 kg per 1,000 kg of water + bitumen + emulsifier + acid, once the primary emulsion has been produced. Aggregates: identical to those of Example 1

The steps for manufacturing the coated materials are the same as in Example 1 except for the humidification of the aggregates: an aqueous solution of concentration 10% by weight in Stabiram® MS6 is added to the dry aggregates, the amount used being 1, 2 g per 100 g of dry materials. It is completed by adding 4.6 g of water per 100 g of dry aggregates. The bitumen content of the coated materials is 6 g per 100 g of dry aggregates. Stabilization times of 46 s and 50 s are obtained respectively. We note for emulsion 2.2 foaming of the water of rupture just after destabilization, which we do not observe for emulsion 2.1. When remixing, the system with emulsion 2.1 gives foam after 150 s, while the system with emulsion 2.2 gives foaming after only 2 s.

For mixes 2.1 and 2.2, another test is carried out by reducing the speed of rotation during the remixing to approximately 1 rpm. There is no foaming of the breaking water for the mix produced with emulsion 2.1. A breaking water foaming is obtained for the mix produced with emulsion 2.2, but the foaming efficiency is lower than that obtained with a mixing speed of between 3 and 5 rev / s. The nature of the additive A used as well as the conditions of mechanical agitation of the mix, once the destabilization has been carried out, influence the foaming of the breaking water.

Example 3 An emulsion containing neither additive A nor additive B is prepared and used

(3.1), an emulsion not containing additive B but containing only an additive A (3.2) and an emulsion according to the invention (3.3).

Bituminous emulsions contain:

^* 65% by volume of a 70 penetration bitumen marketed by the company Elf,

* 6 kg of cationic emulsifier for emulsions 3.1 and 3.2 and 6.5 kg of cationic emulsifier for emulsion 3.3 (Polyram® SL acidified with acid phosphoric so that the pH of the soap is 2), for 1,000 kg of water + bitumen. In emulsion 3.2, PAmphoram® CP1 from Ceca (solution of 60% by weight of amino acid: coco amino propanoic acid and 40% by weight of isopropanol or propylene glycol) is added at the rate of 3 kg for 1 t d water + bitumen + emulsifier + acid, once the primary emulsion has been produced. Emulsion 3.3 is prepared by adding NH ₄ CI salt to emulsion 3.2 in a proportion of 0.5 kg per 1 t of water + bitumen + emulsifier + acid. Asphalts prepared from bituminous emulsions 3.1, 3.2 and 3.3 have destabilization times of 30 s, 32 s and 27 s respectively. Aggregates: granite

Grain size: 0/2 mm: 40%; 2/6 mm: 12%; 6/10 mm: 48%. Content of fillers: around 7% by weight.

The addition water content in the mix is 7 g per 100 g of dry aggregates. The bitumen content is 6 g per 100 g of dry aggregates. The aggregates are placed in a planetary mixer (SR Consulting, type

SRC5A, rotation speed 30 rpm) where they are kneaded for 30 s. The addition water is then poured in and a new mixing is carried out for another 30 s before adding the emulsion. The mixing of all the components of the mix is continued for 1 min and then the mix obtained is stored for 1 h in a bowl. After possible disintegration by hand in the event of solidification of the mix, the mix is remixed by hand for 3 min either in a bowl or in a planetary mixer previously described, before introducing it into the mold and placing it compacted.

The asphalt is compacted using the Giratory Shear Press (Invelop Oy ICT-100RB model): at the end of the bowl, the asphalt is placed in a PCG mold (cylindrical mold with a diameter of 100 mm and a height of 25 cm) then it undergoes compression at 0.6 MPa, with a deflection angle of 1 °, for N turns or gyrations. At the end of compaction, the test piece is weighed again, which makes it possible to calculate the quantity of water discharged during compaction. The vacuum ratio is calculated by measuring the height of the coating before and after compaction. The specimens are fractured after their storage for 1 hour in simple compression at a speed of 200 mm / min using a press (INSTRON, model 4482). Cohesion is defined as the maximum value of the reaction force of the test piece on the jaws during deformation until fracture.

Manual remixing does not make it possible to obtain breaking water foam for the emulsion 3.1 of the prior art, on the other hand there is foaming for the emulsion 3.2 after 45 s and after only 35 s for the emulsion 3.3.

For samples intended for PCG compaction, manual re-mixing for 3 min. The results of compaction, drainage and cohesion are as follows: emulsion 3.1: porosity after 60 girations: 14.6% - amount of water drained: 46% - cohesion 15.5 kN emulsion 3.2: porosity after 60 girations: 12 , 8% - amount of water drained: 59% - cohesion: 18.1 kN emulsion 3.3: porosity after 60 gyrations: 12.6% - amount of water drained: 61% - cohesion: 18.5 kN

The advantage is shown that there is a foaming of the breaking water with regard to the efficiency in terms of compaction, drainage of the breaking water and cohesion.

It is found that the emulsion 3.3 according to the invention gives the best results.

We use emulsion 3.2 to make a mix which we mix again this time with the planetary mixer, therefore at a lower speed than manually, for 3 min: we do not obtain foaming of the breaking water: the influence stirring speed is essential to obtain foaming. The compaction and drainage results are as follows: porosity after 60 gyrations: 14.1% - amount of water drained: 49% - cohesion: 15.9 kN

The emulsion 3.2 is therefore advantageous in terms of compaction, drainage of the break water but its effectiveness is much less good when it is not implemented according to the process of the present invention (no foaming of the water). Example 4

The aggregates are kneaded in a bowl with the addition water for 30 s before adding the emulsion. The mixing is continued for 80 s for the emulsion containing no additive A and B and for 120 s for the emulsion according to the invention. The bituminous mixes are spread out in the form of a pancake on a support impermeable to breaking water to a thickness of approximately 1 cm. After 15 min, 3 round trips are made on the cake with a 5 kg cylindrical roller by pushing it manually over the entire surface of the cake. The surface of the cold poured mix is then dried by simple contact with a dry cloth for 30 s. By difference between the mass of the wafer before compaction and the mass of the wafer after compacting and drying, the amount of water lost during compaction is deduced.

An emulsion containing neither additive A nor additive B (4.1) and an emulsion according to the invention (4.2) are prepared and used to manufacture cold-cast mixes. Bituminous emulsions 4.1 and 4.2 contain:

^* 65% by volume of a bitumen of penetrability 70 sold by the company Total, * respectively 7 kg and 7.5 kg of cationic emulsifier (Polyram® S marketed by the company Ceca acidified with hydrochloric acid so that the pH of the soap is 2), for 1 t of water + bitumen. To the emulsion containing 7.5 kg of cationic emulsifier for 1 t of water + bitumen, PAmphoram® CP1 (30% of active material - additive A) is added up to 3 kg for 1 t of water + bitumen + emulsifier + acid. Then NH ₄ CI salt (additive B) is added up to 0.5 kg per 1 t of water + bitumen + emulsifier + acid.

Aggregates: La Bouvraie Granulometry: 0/2 mm: 55%; 2/6 mm: 45%

Content of fillers: around 9% by weight.

The addition water content in the mix is 8 g per 100 g of dry aggregates. The bitumen content is 7.5 g per 100 g of dry aggregates.

The destabilization times of emulsions 4.1 and 4.2 are respectively 90 s and 100 s. Despite the destabilization of the emulsion 4.2 obtained after 100 s during the manufacture of the cold-cast mix, it is possible to spread the mix in the form of a cake, as for the ECF produced from the emulsion 4.1, the spreading being after 120 s of mixing, because the foam appears and the mix then has a fluid appearance. During compaction, the quantities of water drained are respectively 47% and 59% expressed as the ratio of the quantity of water drained to the total quantity of water involved during the preparation of the mix: quantity d addition water + amount of water in the continuous phase of the emulsion.

The emulsion 4.2 according to the invention implemented in a manufacturing process according to the invention therefore makes it possible to significantly improve the drainage of the breaking water compared to the bituminous emulsion 4.1.

Claims

1. Process for the production of cold poured mixes, open, semi-dense, dense, storable and grave-emulsions from aggregates and bituminous emulsions, characterized in that after destabilization of the emulsion and appearance of l break water, the mix is subjected to sufficient mechanical stirring so that the foaming of the break water ^* is observed at the latest after 1 min of mechanical stirring for cold mixes of type 1, ^* at later after 3 min of mechanical agitation for type 2 cold mixes. 2. Method according to claim 1 characterized in that the bituminous emulsions are chosen from * cationic, anionic or nonionic bituminous emulsions containing in addition • at least one additive chosen from A1 - polyoxyethylated nonionic surfactants, alone or as a mixture, of raw chemical formulas: Rχ [0 (C ₂ H ₄ )] _y OH or R _x CO [0 (C ₂ H ₄ )] _y OH where R _x represents either a linear or branched carbon chain, saturated or not, substituted or not, or an alkyl (ene) phenyl, or one of the preceding chains for which hydrogen is partially or totally substituted by fluorine, x represents the number of carbon atoms of the carbon chain or of alkyl (ene) phenyl, y represents the number of ethylene oxide units, with 7 ≤ x ≤ 22, O≤ y ≤ 8 and preferably y ≤ 6 for the molecules corresponding to the first crude formula with 7 ≤ x ≤ 22, 2 ≤ y ≤ 8 and preferably y ≤ 6 for the molecules corresponding to the second formula, A2- polyoxyethylated nonionic surfactants, alone or in mixture, of raw chemical formulas: R _x [0 (C ₂ H ₄ )] _y OH or RχCO [0 (C ₂ H ₄ )] _y OH where R _x represents a linear or branched poly (dimethylsiloxane) chain where x represents the number of silicon atoms, y represents the number of ethylene oxide units, with 4 ≤ x ≤ 15, 4 ≤ y ≤ 20 A3- amphoteric surfactants, alone or in mixture, of raw chemical formulas: Rx [N ⁺ (CH ₃ ) ₂ ] (CH ₂ ) _y A or R _x NH (CH ₂ ) y COOH or R _x NH (CH ₂ ) _y B, C where R _x represents the same chains as in A1 A represents the group COO ^~~ , the group OS0 ₃ ^~~ out the group OS0 ₂ ^~~ , B represents the group OS0 ₃ ^~ or the group OS0 ₂ ^"~ , C represents either the counter cation of alkali or alkaline earth metal, iron, copper, manganese, zinc, or the ammonium cation, in proportion such that the salt is electrically neutral y represents the number of CH _{2 units} , with 7≤ x ≤ 22, O≤ y ≤ 4. A4- amphoteric surfactants, alone or in mixture, of raw chemical formulas: Rx [N ⁺ (CH ₃ ) ₂ ] (CH ₂ ) _y A or R _x NH (CH ₂ ) _y COOH or R _x NH (CH ₂ ) _y B, C where R _x represents the same chains as in A2 A represents the same groups as in A3 B represents the same groups as in A3 C represents the same cations as in A3, in proportion such that the salt is electrically neutral y represents the number of CH _{2 units} , A 5- the alkanolamide surfactants, alone or as a mixture, of crude formula: RχCONH [(CH ₂ ) _y OH] or R _x CON [(CH ₂ ) _y OH] [(CH ₂ ) _z OH] where R _x represents the same chains as in A1 with 7 ≤x ≤ 22, 1 ≤ y ≤ 4, 1 ≤ z ≤ 4 A6- the amine oxide surfactants, alone or in mixture, of crude formula: R _X N (CH ₂ ) ₂ - O where R _x represents the same chains as in A1 with 7 ≤ x ≤ 22 • and optionally at least one additive B chosen from B1- the salts, alone or in mixture, of crude chemical formula: NH ₄ X where X corresponds to a halogen element B2- the salts, alone or in mixture, of crude chemical formula: T _u NH ₄ Y where T _u represents a linear or branched carbon chain, saturated or not, substituted or not, u represents the number of carbon atoms of the carbon chain, Y corresponds to a halogen element with 1 ≤ u ≤ 6 B3- the salts, alone or in mixture, of crude chemical formula T _u NH ₄ Y where T _u represents an alkyl (ene) phenyl, u represents the number of carbon atoms in the alkyl (ene) phenyl, Y corresponds to a halogen element with 1≤ u ≤ 12 B4- alkyl (ene) polyamines and more particularly alkyl (ene) propylene diamines, alkyl (ene) dipropylene triamines and alkyl (ene) tripropylene tetramines in which the alkyl (ene) chain has between 1 and 12 carbon atoms * and cationic emulsions containing at least one alkyl (ene) amidoamine. 3. Method according to claim 1 or 2 characterized in that the addition water contains at least one additive A and optionally at least one additive B as defined in claim 2. 4. A method of manufacturing cold-cast mixes according to any one of claims 1 to 3, characterized in that the mixing continues beyond the destabilization of the emulsion in the ECF machine, until obtaining foaming of the rupture water. 5. A method of manufacturing open, dense mixes and grave-emulsions according to any one of claims 1 to 3, characterized in that the breaking water can foam during the coating in the mixer and the process is continued. mixing during implementation in a grader or finisher. 6. Bituminous emulsion comprising at least one bituminous binder, of water, at least one cationic, anionic or nonionic surfactant emulsifier, characterized in that it additionally contains at least one additive A and at least one additive B as defined in claim 2.