EP0736629B1 - Process and apparatus for applying an adhesive layer and road surface comprising such a layer - Google Patents

Abstract

The procedure consists of applying a surfactant (6) to the base layer (4), followed by a bitumen-bound material (3) sprayed with bituminous emulsion (3). The emulsion is sprayed with a breaking agent (7), e.g. as it is applied, to leave a non-adhesive surface. The bituminous emulsion contains between 40 and 70 wt.% of a binding agent, and is cationic in nature, while the breaking agent is an aq. soln. of an anionic surfactant or polymer, e.g. polymer salts or acrylic acid-based copolymer.

Description

The invention is in the field of the implementation of road-type coatings, and more specifically concerns the process for obtaining a bonding layer allowing the bonding, of a layer of bituminous mixes on a support (see document GB-A-2 167 975).

The invention also relates to the coating of the type road including a bonding layer obtained by the process.

The invention also relates to a construction machine allowing the implementation of this process.

The realization of a coating, of road type, results from the implementation of successive layers. Among these different layers, at least one bituminous layer covers a lower layer, called the support layer. The nature of the support layer can be relatively varied, in concrete, paved, or bituminous mixes for example. The state of this support is also the subject of many variations. he can be new or old, poor or worn, rough or smooth, wet or dry, dusty or not, etc.

A bonding layer makes it possible to ensure bonding between the layer of bituminous mixes and its support. Its role is also to ensure the impermeability of the roadway. In general, this layer is avoided from an anhydrous binder which presents a risk of trapping the fluxes between the two layers situated on either side, and that the low dosages of bituminous binder to be used for the bonding layers are incompatible with traditional spreading methods: 300 to 600 grams of residual bitumen per m ² .

In certain constructions, the roadway includes several successive layers of asphalt. These layers are linked together by a bonding layer. Layer lower asphalt then plays, opposite the layer of attachment, the role of support layer.

In some cases, the top layer of the roadway is coated with a surface coating. This deposit allows restore certain surface properties, in particular roughness and impermeability, with worn coating. These coatings are composed of hydrocarbon binders, made fluid for spreading either in the form of an aqueous emulsion or by addition of light distillation fractions to bitumen petroleum or coal. They may be anhydrous coatings which are mixtures of bitumens and hydrocarbon products.

Numerous studies have highlighted the importance and the required properties of the bonding layer. Layers of poor quality hooking generate phenomena of separation of the layers of the roadway. This phenomenon frequently found leads to heavy maintenance work and expensive. The standards and specifications specify that the bonding layer must be regular and continuous and that in no case is it sanded.

This bonding layer is generally produced with a cationic emulsion of pure bitumen or modified bitumen. The usual recommended dosages are between 300 and 600 g of residual bitumen per m ² . The dosage depends on the state of the support and the nature of the mix used.

There are currently several methods for implementation of a bonding layer.

In a method, which we will call traditional, an emulsion layer is deposited by a machine of the type spreader, comprising a tank and a spreading ramp. The application is made on several tens of meters, sometimes a few hundred, ahead of an implementation workshop work and deposit of a bituminous mix.

This method, although widely used, only gives moderately satisfied and presents many disadvantages. The breaking time of the emulsions used is generally longer than 30 minutes, so that truck tires, supplying the site, driving on the fresh layer, reduce in places the thickness of the residual layer and cause pollution, by bitumen training, the paths they take by the after. On the other hand, elements of this bonding layer are carried by the paver tracks, used for depot of the asphalt layer, which rolls over the bonding layer. This premature degradation of the bonding layer locally causes the emulsion to rise through the mix, causing the surface to be glazed. When the support has a weak cohesion, the detachment by bonding layer plate, causing part of the support elements, leads to the formation of holes and bumps. In all cases, the defect of the bonding layer between the two layers of bituminous mixes, due to its tearing, induces a very irregular bonding and therefore insufficient of these two layers between them.

It has been proposed, for several years, devices associated with the paver that allow to apply the adhesion layer just before laying the asphalt. However, this approach also presents many disadvantages.

When the spreading means are arranged at the front of the paver, the wheels or the tracks of the mobile assembly are caused to circulate on the freshly spread layer, and therefore to degrade it. On the other hand, the pavers are intended coatings on wide pavements variable, it is then necessary to provide a device for adjustable ramps. In addition, the travel speeds of the finisher (3m / min to 6m / min) are much slower than those conventional spreaders (30m / min to 150m / min). The result that the flow rate of the binder must be adapted. All of these conditions leads to complex ramp arrangements, and to delicate adjustment conditions, making it difficult to drive to achieve a very homogeneous bonding layer.

This method also leads to difficulties supply of different materials, on vehicles, whose range is not always synchronized.

In this method, drying and breaking the emulsion are made in a very short time, by setting in contact with the bonding layer with hot mixes. This results in an impossibility of controlling the layer. attachment thus produced, both in quantity and in quality.

It has also been proposed to make a layer attachment by depositing fine capsules containing a binder bituminous anhydrous. These capsules have an envelope a solid and stable material at room temperature, which melts and degrades at the processing temperature of the mix to release the binder. This idea is very difficult to implement, and does not provide a homogeneous distribution of the bonding layer over the entire support surface.

However, poor bonding systematically leads to weakness in the pavement structure, and degradation by faster fatigue.

The object of the invention is to avoid these drawbacks. It is also to have a process allowing a rupture rapid bituminous emulsion, no sticking to tires of supplying vehicles and vehicles which would accidentally circulate on this layer freshly spread, good resistance to the passage of paver tracks, to adapt the viscosity of the binder the emulsion used under local climatic conditions, ensure perfect bonding of the bonding layer to the support, and more particularly when it is wet, and again to allow the possibility of carrying out quality and quantity checks on the bonding layer Implementation.

Another object of the invention is to have the road-type coating including a bonding layer obtained by this process.

Yet another goal is to have a construction of pavements allowing the implementation of this process.

• application d'un agent tensioactif sur le support,
• application de la composition bitumineuse,
• application d'un agent de rupture.

The invention relates to a method for obtaining a bonding layer, a layer of bituminous mixes on a support, by spreading a bituminous emulsion. According to the invention, the method comprises the following stages:

• application of a surfactant on the support,
• application of the bituminous composition,
• application of a breaking agent.

The application of the surfactant on the support leads to a significant improvement in the bonding of the layer of attachment to it, whatever its nature and state. The emulsion used is either a pure bitumen emulsion, or an emulsion of bitumen modified by polymers. This emulsion has no flux. This quality allows avoid any rise of these fluxes in the mix. This rise is likely to soften the binder of the mix surface, and thus cause the appearance of areas repeated, ruts or holes, by traffic.

Other technical characteristics may be combined to obtain specific advantages.

In the most common case of cationic emulsions, the breaking agent is sprayed onto the emulsion brush bituminous falling from the spreader.

In the general case, the breaking agent is projected onto bituminous emulsion, in this particular case, the solution of the breaking agent is sprayed simultaneously with the emulsion bituminous falling from the spreader. This provision, although than preferred, is not essential. It allows the rupture in the mass, of the bituminous emulsion.

The bituminous emulsion comprises a binder whose content is between 40 and 70% by weight.

Bitumen used for the constitution of the emulsion is taken from classes 180/220, 70/100, 60/70, 35/50, and 25/35. This process allows the use of a bitumen emulsion hard. The choice of emulsion used can be made by suitability for climatic, temperature and humidity, relative to the period and place of placing of the process.

In the most usual case, cationic emulsions, the breaking agent applied, is an aqueous solution of at least minus one of the products taken from the list of strong bases, anionic surfactants or anionic polymers. In the case of the use of an anionic emulsion, the agent of applied rupture, is an aqueous solution of at least one of products put in the list of strong acids, surfactants cationic, or cationic polymers, for example of the type quaternary ammonium. The application of the breaking agent allows rapid solidification of the bonding layer. This phenomenon avoids sticking of the layer to the tires of the machines which would be brought to circulate on the deposit. This absence of gluing from above, is also appreciated personnel carrying out the implementation. The site is thus more easily clean.

In a preferred solution, the breaking agent is a anionic polymer, which due to its charge and its long chain molecular structure promotes agglomeration bitumen particles. By anionic polymer is meant, salts of polymers or copolymers based on acid acrylic, e.g. sodium polyacrylate, ammonium or potassium, or a sodium salt of a copolymer acrylic acid and acrylamide. In addition, it is about anionic polymers in neutral pH medium, not only in medium of acidic pH These breakers are neither corrosive or toxic, which makes them easy to use and limit the dangers involved in their implementation.

The invention also relates to a coating of the type road, composed of successive layers, comprising at least a support layer and a bituminous layer. At least one bituminous layer connected to a lower layer by through a bonding layer obtained by the method according to the invention or one of these particular modes of Implementation.

The invention also relates to a machine for pavement construction, comprising on a chassis, mounted on displacement means, spreading means of a bituminous emulsion, and also comprising means application of a surfactant and means application of a composition disrupting agent bituminous.

This machine thus allows the implementation of the process obtaining a bonding layer according to the invention.

Other features, goals and benefits will emerge from the following description, given as example and without limiting characters, opposite the drawings annexed, on which:

Figure 1 shows a side view of a pavement construction, allowing the implementation of method according to the invention.

Figure 2 represents, a detail of all of the spreading and application means equipping the vehicle with the car 1.

The pavement construction machine 1, shown in Figure 1 is of the spreader type. It features on a chassis, mounted on displacement means 2, means for spreading 9 a bituminous emulsion 5. This machine 1 also includes means for applying an agent surfactant 6 and, other means of application 11, of an agent 7 of the bituminous composition 5.

All of these means 9, 10, 11 allow the implementation work of the process for obtaining a bonding layer at quick setting. This set is shown schematically in Figure 2. A first application means 10, consisting of a ramp provided with nozzles, allows to deposit on the support layer 4 a solution of surfactant 6. On this layer 4 thus treated, is spread a bituminous solution 5. In this example, a solution of rupture agent 7 is sprayed simultaneously onto the emulsion. In this case, the breaking agent 7 is applied to the brush 8 of the bituminous emulsion 5. The brush 8 of the emulsion corresponds to the product included in the zone located between the spreading means 9 and the ground.

The breaking agent 7 is sprayed onto the emulsion bituminous 5, and preferably on the brush 8 of the emulsion. An equivalent solution also consists in projecting breaking agent 7 on only part of the brush 8 emulsion. This part can be located in half lower of the brush 8. The angle of incidence of the jet of rupture 7 can be chosen according to the power of the jet, products used and weather conditions.

Various agents for breaking hydrocarbon emulsions are known: their action generally results from a neutralization reaction or even from precipitation of the emulsified medium. The nature of the breaking agent depends essentially on the emulsified bitumen and the emulsifying agent. In the case of a cationic emulsion, of pH greater than 1.0 and containing 60 to 75% by weight of bituminous binder and from 0.1 to 0.5% by weight of an emulsifier of the fatty amine hydrochloride type or imidazoline, the breaking agent can be an aqueous solution, of concentration between 5 and 35%, of a strong mineral base, such as sodium hydroxide, or of an anionic surfactant, such as an alkyl (C ₁₀ -C ₂₀ ) sulfate, or a mixture thereof. The quantity of solution of breaking agent projected generally corresponds to 0.2 to 1% by weight of agent relative to the weight of the emulsion to be treated.

We prefer to use an emulsion of hard bitumen, 35/50 penetration, preferably with a binder content between 55 and 65% by weight. Temperature of application of the emulsion being between 60 and 80 ° C.

In the following, we compare three examples of implementation work of process for obtaining a bonding layer.

In these examples, the bituminous emulsion 5 contains 60% of pure bitumen, of class 35/60, the chemical formula of which comprises 0.3% by weight of imidazopolyamine. The application temperature of this emulsion is between 60 and 80 ° C. The dosage of this emulsion corresponds to an amount of 1 kg / m ² .

The surfactant emulsion 6 is a preparation based on alkylamido polyamine and alkyl imidazo polyamine in organic solution, with dilution corresponding to one part of pure product for nine parts of water. This solution being applied at room temperature, and at a dosage of 50 g / m ² .

Three solutions of disrupting agents 7 make it possible to make comparisons. We will call emulsion A, a solution without breaking agent, emulsion B, a solution of an anionic breaking agent, and emulsion C, a solution of anionic polymeric breaking agent. The solution of the breaking agent 7 corresponds to the dilution of one part of pure product for two parts of water. The application is made at room temperature, and the dosage corresponds to an amount of 6 g / m ² of pure product.

Emulsion A does not allow a speed of rupture of the bituminous emulsion 5 less than 15 min. This causes sticking phenomena, and poor quality of the bonding layer thus deposited.

In the case of emulsion B, the rupture takes place after 5 min. However, after this 5 min delay, the film deposited is always slightly sticky.

In the case of emulsion C, the rupture takes place in the 3 minutes after application. After 5 minutes, the deposited layer is non-sticky and can be circulated. The layer thus deposited, avoids the phenomena of sticking and degradation. These properties are also appreciated by the personnel carrying out the implementation.

The process for obtaining a bonding layer, using emulsion C, can be produced on a support wet and / or slightly dusty, the bonding layer retaining the properties mentioned above.

Claims (10)

1. A process for obtaining a bonding layer (3), a layer made of bituminous coated coated materials on a support (4) by spreading of a bituminous emulsion (5), characterized in that it comprises the following steps :

   application of a surface-active agent (6) on the support (4),

   application of the bituminous emulsion (5),

   application of a breaking agent (7).
2. A process according to claim 1, characterized in that the breaking agent (7) is projected on the brush (8) of the bituminous emulsion (5) falling from the spreader (1).
3. A process according to anyone of claims 1 or 2, characterized in that the bituminous emulsion (5) comprises a biding agent whose content ranges between 40 and 70% in weight.
4. A process according to anyone of claims 1 to 3, characterized in that the bituminous emulsion (5) contains a bitumen chosen among the classes 180/220, 70/100, 60/70, 35/50 and 25/35.
5. A process according to anyone of claims 1 to 4, characterized in that the bituminous emulsion (5) spread is of the alkaline type and that the breaking agent (7) used is an aqueous solution, with at least one of the products taken from the list of the strong bases, anionic surface-active agents and anionic polymers.
6. A process according to claim 5, characterized in that the said anionic polymers are acrylic acid-based polymer or copolymer salts.
7. A process according to anyone of claims 1 to 4, characterized in that the bituminous emulsion (5) spread is of anionic type and that the breaking agent (7) used is an aqueous solution, with at least one of the products taken from the list of the strong acids, cationic surface-active agents and cationic polymers.
8. A process according to claim 7, characterized in that the said cationic polymers are of quaternary ammonium type.
9. A road-type coating, consisting of successive layers, comprising at least one supporting layer (4) and one bituminous layer, characterized in that at least one bituminous layer is linked to an inferior layer via a bonding layer (3) obtained by the process according to one of the previous claims.
10. A machine (1) for the construction of carriageways comprising on a frame, mounted on displacement means (2), spreading means (9) of a bituminous emulsion (5), characterized in that it also contains application means (10) of a surface-active agent (6) as well as other application means (11) of a breaking agent (7) of the bituminous compound (5).

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