EP0215139B1 - Method for renovating road surfaces - Google Patents

Abstract

Renovation of esp. deformed road surfaces, using old asphalt, involves; (a) heating the surface with the old asphalt layer; (b) loosening the hot old asphalt layer and uniformly distributing the particles in it on the width, so that the particles are mixed thoroughly; and (c) consolidating the particles in the renovated layer. Before mixing, the particles are treated with amorphous polyolefins (I) as copolymers of olefins with selected monomers so that the mixed prod. is semi-hard to soft and tends to stick at elevated outside temps., 0.3-0.5 wt.% w.r.t. the old asphalt or ca. 7% of its total binder content are used.

Description

• Die zu erneuernde Fahrbahndecke mit der oberen Asphaltschicht wird aufgeheizt;
• die erhitzte Asphaltschicht wird aufgelockert, und dabei erhaltene Partikel werden gleichmäßig auf die Einbaubreite verteilt, wobei eine Durchmischung der Partikel erfolgt; die in neuer Schicht verteilten Partikel werden zum Erhalt einer Fahrbahndecke verdichtet.

The invention relates to a method for renewing, in particular, deformed road surfaces using old asphalt with the following features:

• The road surface to be renewed with the upper layer of asphalt is heated;
• the heated asphalt layer is loosened, and the particles obtained are evenly distributed over the pave width, with the particles being mixed; The particles distributed in a new layer are compacted to obtain a road surface.

In known processes of this type, work is either carried out without the addition of fresh asphalt (reshape process), or fresh mix is applied to the piastified old ceiling (Repaven), or the heated material is additionally peeled off and fed to a compulsory mixer, in which new fresh mix is added and mixed (remixing). The application of these methods depends on the quality of the old asphalt and the requirements for the new pavement. Old pavement decks become bituminous over time, and their binding capacity also decreases, so that paved pavement renewed with old asphalt does not give the expectation of the quality that is possible with new material.

Bituminous binders have therefore already been modified in order to adapt them to use in the renewal of asphalt surfaces (FR-A-2 559 516). Specifically, the binder is modified with an elastomer in the form of an emulsion or aqueous dispersion and these modified binders are mixed with the old asphalt. Modified bituminous binders are widely known (FR-A-2 200 335, FR-A-2 284 653, "Highways and Public Works" Volume 50, June 1982, pp. 9-11). The amorphous polyolefins of the. Specification according to the invention are not applied.

The invention has for its object to provide a method for renewing road surfaces using old asphalt, with which the quality of new road surfaces in terms of durability and grip is achieved and exceeded.

The object is achieved in that, before the particles are mixed, amorphous polyolefins are added such that the mixed product is half-hard to soft and tends to stick even at elevated outside temperatures, the amorphous polyolefins as copolymers of α-olefins with selected monomers have the following parameters: melt viscosity approx. 8000 mPas (measured with the rotary viscometer at approx. 190 ° C), softening point approx. 105 ° C (measured with ring and ball according to DIN 52011), penetration 20 (according to DIN 52010), breaking point -30 ° C ( measured according to Fraass, DIN 52012); the amount added is 0.3 to 0.5% by weight of the processed asphalt or approximately 7% of its total binder content.

The characterized amorphous polyolefins are commercially available from Chemischen Worken Hüls AG under the name "Vestoplast", the "Vestoplast 708" being particularly suitable. The characterized amorphous polyolefins are available as granules, whereby the surface of the product is provided with a separating agent and with a powder to prevent the granules from caking. "Vestoplast" is intended for the production of hot melt adhesives and hot melts. "Vestoplast" can also be used directly as a laminating adhesive.

However, this adhesive property makes direct processing difficult when renewing pavements, from the addition to the distribution in the old asphalt particles.

According to a preferred further development of the invention, the amorphous polyolefins are therefore added dissolved in an aromatic oil. The aromatic oil must be compatible with the bitumen. The quality WD3 lubricant has proven to be particularly suitable. The amorphous polyolefins can be dissolved in the aromatic oil at about 100 ° C. and a mixture solution with half polyolefins and half aromatic oils is obtained. This mixture solution should have a waxy consistency at room temperature. The mixture solution is well suited to penetrate the old asphalt and to refresh the aged bitumen and make it more supple. When mixed with asphalt, the amorphous polyolefins also show good adhesion to the granular components of the pavement, which explains the increased stability of the renewed pavement.

• Fig. 1 eine fahrbare Anlage zur Erneuerung von Fahrbahndecken, von der Seite gesehen und in schematischer Darstellung, und
• Fig. 2 eine vergrößerte Einzelheit daraus, in perspektivischer Darstellung.

The invention is described with reference to the drawings. It shows:

• Fig. 1 is a mobile system for the renewal of road surfaces, seen from the side and in a schematic representation, and
• Fig. 2 is an enlarged detail thereof, in a perspective view.

In the new method, a device known per se, as shown in FIGS. 1 and 2, can be used. This consists of a chassis 1 with a driver's cab 2 mounted at the rear and a number of devices which are mounted on the chassis. In the following, only the facilities that are important for the new procedure should be mentioned. At the front end of the chassis, a tank 3 is provided, which is normally provided for receiving bitumen and has heating devices and a line to a mixer 4. Instead of the bitumen, a mixed solution of amorphous polyolefins and aromatic oils is filled in, as will be described in more detail in a later section. In the area below the tank 3 and in the front intermediate wheel area, a heater 5 is provided for the asphalt layer 10 located below. The heating zone 5 is followed by a loosening device 6, which acts as a rigid loosening device or can be designed as a rotating loosener. A feed screw 7 is arranged in the direction of movement. The loosened old asphalt layer is fed to the mixer 4, which is designed as a compulsory mixer, above which a row of nozzles for distributing the mixed solution from the tank 3 is arranged. In the mixer 4, the old asphalt particles are thoroughly mixed with the mixed solution and the mixture obtained is fed to a spreading auger 8 in front of a screed 9. The processed material is installed by the auger and the screed in the appropriate width as a new road surface, which is then compacted by a roller, not shown.

Altasphalt, modifiziert mit Polyolefinen und aromatischem Öl der Zusammenzetzung "Vestoplast" und "WD-3"

Abbindemittel modifiziert: 7% "Vestoplast" 7% "WD-3"The renewed road surface showed increased stability and durability even compared to normal fine asphalt concrete, as the following test with a molded Marshall body results in that each compacted at a compression temperature of 130 to 140 ° C and at a load of 52.5 kg at 70 ° C was loaded with a stamp of 5 cm ² , the following penetration depths being measured: normal asphalt fine concrete 0/11

Old asphalt, modified with polyolefins and aromatic oil of the composition "Vestoplast" and "WD-3"

Setting agent modified: 7% "vestoplast" 7% "WD-3"

The "vestoplast" is a mixed product of amorphous polyolefins which can be addressed as copolymers of α-olefins with selected monomers. The mixed product is semi-hard to soft and is insufficient for gluing even at elevated outside temperatures. "Vestoplast" is supplied in various standard types by Chemische Werke Hüls AG, D-4370 Marl, and "Vestoplast 708" has proven to be particularly suitable for the intended application. The melt viscosity at 190 ° C, measured with the rotary viscometer, is about 8000 mPa s. The softening point, measured according to DIN 52011 with a ring and ball, is approximately 105 ° C. The penetration 100/25/5 based on DIN 52010, measured in 0.1 mm, is approximately 20. The breaking point according to Fraass DIN 52012 is approximately -30 ° C. Because of its amorphous character, "Vestoplast" does not have a sharp melting point, but a softening area. As with all thermoplastics, the viscosity of the melt drops with increasing temperature.

• Farbe ASTM (American Association for
• Testing Materials):
• >8

The aromatic oil of quality WD-3 can be obtained from Chemische Betriebe GmbH Pluto, D-4690 Marl, and has the following physical and mechanical properties:

• Color ASTM (American Association for
• Testing Materials):
• > 8

• 1,008

Density at 15 ° C:

• 1,008

• 1380

Visc. cSt / 40 ° C:

• 1380

• 29

Visc. cSt / 100 ° C:

• 29

• 420

Start of boiling:

• 420

• 540

End of boiling:

• 540

• C_a 0/0 43 (aromatisch)
• C_" 0/0 25 (nastenisch)
• Cp 0/0 32 (paraffinisch)

C distribution according to Din:

• C _a 0/0 43 (aromatic)
• C _" 0/0 25 (nasty)
• Cp 0/0 32 (paraffinic)

• 22 h/107°C: 0,2

Evaporation loss according to ASTM D 972:

• 22 h / 107 ° C: 0.2

• unter 0,01

Ash:

• less than 0.01

• 0,03 0,03 Sediment:

Conradson Gew. 0/0: 2.9 (tendency to coke) sulfur: 3.57

• 0.03 0.03 sediment:

The mixture solution of "Vestoplast" and "WD-3-ÖI was prepared in a heatable tank with an agitator at about 100 ° C. The mixing ratio is about 50:50% by weight, but deviations of ± 10% are easily possible because a thin liquid mixture solution can also be obtained at the specified temperature, which can be atomized into very fine droplets and can therefore be metered well are stored and made thin if necessary in the heatable tank 3.

The amount added depends primarily on the binder content of the asphalt, namely the polyolefins should amount to 7 ± 1% by weight of the total binder content in the renewed pavement. This total binder content is composed of the bitumen content found, the polyolefins added and the aromatic oil added, and any bitumen addition required to achieve the desired binder content. If, for example, a binder content of 6% is to be achieved and a bitumen content of 4% is found, there is an addition of about 0.4% by weight of polyolefins, based on the processed asphalt. If aromatic oil was added in approximately the same amount, then about 1.2% of bitumen would have to be added in order to achieve the desired total binder content of 6%. In practice, the amounts of polyolefins added are then about 0.3 to 0.5% by weight of the processed asphalt.

The total binder content is therefore the reference basis for the addition of polyolefins, the proportion of which, as stated, should be 7 ± 1% by weight of the total binder content. When using the mixed solution of polyolefins and aromatic oils in a weight ratio of 1: 1, a proportion of about 14% by weight of the total binder content is then obtained.

The process is not limited to processing old asphalt alone. During the reprocessing, minerals or finished mix can be added to the asphalt if there are reasons for this.

The practical application of the process can be realized with all machines that are suitable for the reprocessing of old road surfaces on the spot (recycling in place).

In machines for the Repave process mentioned at the outset, the mixture solution of the polyolefins and the aromatic oils is sprayed onto the roadway to be renewed, which was previously heated. The roadway to be renewed is milled off, and as a result, as well as a downstream whirler, the particles generated are mixed intensively with the mixed solution. With the screed, the material is evenly installed and subsequently compacted in a known manner using rollers.

The polyolefins can also be applied as fine granules to the highly heated surface of the roadway to be renewed and can be mixed intensively by subsequent milling and whirling or even in a compulsory mixer.

In this case, aromatic oil can also be added to refresh the aged bitumen.

• a) Das aromatische Öl erweicht und frischt das gealterte Bitumen auf, macht es geschmeidig und begünstigt zugleich die Verteilung der Polyolefine;
• b) die Polyolefine erhöhen die Haftfestigkeit des Bindemittels und modifizieren dieses im Sinne einer höheren Standfestigkeit, eines höheren Verformungswiderstandes und Alterungsbeständigkeit der erneuerten Fahrbahndecke.

However, the addition as a polyolefin aromatic oil mixture solution is preferred, since it acts in two ways:

• a) The aromatic oil softens and refreshes the aged bitumen, makes it supple and at the same time promotes the distribution of the polyolefins;
• b) the polyolefins increase the adhesive strength of the binder and modify it in the sense of a higher stability, a higher resistance to deformation and aging resistance of the renewed road surface.

Claims (6)

1. A method of renovating in particular deformed road surfaces using old asphalt having the following features:

the road surface to be renewed with the old asphalt layer (10) is heated up;

the heated old asphalt layer (10) is broken up and particles obtained thereby are uniformly distributed over the construction width, with the particles being thoroughly mixed;

the particles which are distributed in a fresh layer are compacted to produce a road surface; characterised by the following steps:

before the mixing of the particles, an addition of amorphous polyolefins is effected in such a way that the mixed product is semi-hard to soft and already' has a tendency to stick at increased outside temperatures, wherein the amorphous polyolefins as copolymers of a-olefins with selected monomers exhibit the following parameters:

melt viscosity about 8000 mPas (measured with a rotary viscosimeter at about 190°C), softening point about 105°C (measured with ring and ball in accordance with DIN 52011), penetration 20 (in accordance with DIN 52010), breaking point -30°C (measured in accordance with Fraass, DIN 52012); and the added amount is from 0.3 to 0.5% by weight of the treated old_.asphalt or about 7% of its total binder content.

2. A method according to claim 1 characterised in that the addition of the amorphous polyolefins occurs in a condition of being dissolved in an aromatic oil.

3. A method according to claim 2 characterised in that a lubricant of the quality WD-3 is used as the aromatic oil.

4. A method according to claim 2 or claim 3 characterised in that the amorphous polyolefins are dissolved at about 100°C in the aromatic oil and the mixed solution consists approximately half-and-half of the polyolefins and the aromatic oil.

5. A method according to one of claims 2 to 4 characterised in that the mixed solution is of a waxy consistency at room temperature and is highly fluid at about 100°C.

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