FR2718766A1 - Fabricating road-making materials - Google Patents

Abstract

A process for the in-situ prodn. of a cold cast material for the repair and construction of roadways from granulates, bitumen emulsion, water, additives and cut mineral or synthetic fibres comprises incorporating the cut fibres directly in the mixer (6) and/or in the pouring device (7) used to apply the mixt. to the road surface. The device used for this process is also claimed and incorporates coils of fibres (10), a guidance system for the fibres (11), a device (12) for cutting the fibres, and some dispersion devices (13) for injecting the fibres into the mixer (6). The equipment is lorry mounted.

Description

The subject of the present invention is a process for the in situ production of a composite material obtained by mixing cut fibers and a bituminous grout.

The present invention also relates to the device for introducing and cutting fibers adaptable to the machines for manufacturing and spreading bituminous grouts so that these machines can manufacture and spread the composite material.

The invention relates essentially to the repair and maintenance of pavements but can also be applied to the construction of new pavements, particularly in an anti-crack recovery complex.

Traditionally, the maintenance of cracked or faience roads and the coating of new pavements is done by adding a more or less thick layer of asphalt or by applying a surface coating. These two techniques, which are commonly used, do not completely prevent cracks from rising and have a limited lifespan.

We therefore looked for various methods to reduce the rise of cracks on the surface of the roadway.
According to one of these methods, a bituminous mix composed of sand and hydrocarbon binder over a thickness of 2 to 3 cm is interposed between the pavement to be treated or the base to be protected and the wearing course. This process does not ensure the bonding of the layers together, which affects the overall strength.

Another method consists in applying a geotextile on the cracked or faience pavement or on the seat to be protected, on which a surface course is then applied. This process requires several operations (spreading a layer of binder, applying the geotextile product, spreading another layer of binder). This system is often difficult to apply due to the geometric constraints of the support, which can lead to the formation of folds that are difficult to absorb. Among the geotextiles used, those in which glass fibers are incorporated are those which give good results against the rising of cracks. A variant of this process consists in using a fiberglass grid in place of the geotextile.

Another method consists in spreading fibers, cut or not, on a hydrocarbon binder previously spread over the surface to be treated, this layer is then itself covered by another layer of binder. A layer of aggregates is then spread over this set. This process is delicate to carry out and can lead to overdoses by binding.

The purpose of the present invention is to remedy these drawbacks and its objectives are: - to avoid the cracking up of cracks through the wearing courses, both for old cracked or faience pavements as for new pavements where the invention will contribute to delay or suppress the rise of cracks, - increase the fatigue resistance of the wearing course thanks to the high tensile strength of the material object of the invention which is placed under the stretched fiber of the wearing course , - to be used as such as a wearing course for the maintenance of cracked or faience pavements, - incidentally to be used as a waterproofing screed for engineering structures.

The present invention consists in incorporating a high dosage of mineral or synthetic fibers cut to a length of between 15 and 100 mm in a bituminous grout.

Bituminous grouts, also called cold-poured mixes when using 0/10 aggregates, are emulsion mixtures of bitumen, water, aggregates and various additives. These materials are manufactured by mobile equipment which ensures: -the storage and transport of the components on the site, -the dosing and mixing of the materials, -the spreading of the material on the surface to be treated thanks to a sled.

At the outlet of the mixer the mixture is in the form of a pasty grout. This mixture is distributed in the application sled by means of screws before being spread on the road. The material acquires its cohesion after the emulsion has ruptured and after the water in the mixture has been discharged. The layer thus applied is rollable within a period of between 15 and 60 minutes.

The invention consists in incorporating mineral or synthetic fibers into the slurry in a high proportion. In order for the mixture to be homogeneous and to keep its workability, the fibers are cut to a length of between 15 and 100 mm. To achieve this incorporation the invention also relates to a device adaptable to existing machines.

This device is characterized in that it comprises means for storing fibers in the form of strand rolls, means for guiding said strands towards cutting devices, cutters and devices for dispersing the fibers in the mixer and / or in the grout distribution screws.

Among the fibers available on the market, mineral fibers and more particularly glass fibers will be preferred insofar as they have high mechanical characteristics and have a moderate cost.

The length of the cut fibers will be between 15 and 100 mm depending on the effect that one seeks to obtain.

The short fibers have the effect of making the bituminous grout more cohesive while the long fibers are more effective against the rising of cracks.

The fiber dosage will be between 50 and 300 grams per square meter of surface treated,
High dosages will be used for the treatment of cracked or faience pavements or when the material is used in an anti-cracking complex
The formulation of the base bituminous grout will be a 0 / D type formula in which the dimensions of the largest aggregate can be between 6 and 14 mm. Formulas 0/6 will be used when the material is used as an interposing membrane, while formulas incorporating larger aggregates will be used as a wearing course.

The invention will be better understood by referring to Figure (1) showing the device and the operation of a grout machine.

The machines for manufacturing and applying bituminous grouts are generally mounted on trucks.

They include an aggregate hopper (1). these aggregates are dosed and conveyed to the mixer via a conveyor belt (2) or a transport screw. which regulates the flow of the material.

The emulsion is stored in a tank (3) along with the feed water (not shown in the diagram)
The vehicle also includes the storage (4) of various additives (cement, etc.) used in the final composition.

The emulsion, water and additives are injected into the mixer through the metering devices (5).

The mixer (6) mixes all of the materials. The grout thus obtained pours into the sled (7) which includes distribution screws (8) to spread the product before the adjustment device (9)
The device which is the subject of the invention may, for example, be adapted to the material described above in the following manner: the rolls of fiber strands (10) are placed under the aggregate hopper, the strands of fibers are guided by sheaths (II) towards the cutters (l 2), each fiber roll or group of rollers is connected to a cutter -the cutters are preferably located above the mixer and inject the fibers cut into it by 1 through a dispersing device. (13)
However, these cutting and dispersing devices may also be located above the distribution screws (8).

The cutting and dispersing devices are known models, their number depends on the dosage of fibers which it is desired to include in the material.

The cutting and dispersing devices are driven either hydraulically, mechanically or electrically. The rotational speed of the rotor or cutting rotors is controlled by the rotational speed of the conveyor belt (2) so that the flow rate of the fiber flow produced is proportional to the flow rate of the material.

Claims (6)

Claims:  1. Process for manufacturing a cold-cast composite material for the maintenance and construction of pavements made from:  - 0 / D aggregates in which the dimensions of the largest aggregate can be between 6 and 14 mm  - bitumen emulsion,  - water,  - various additives,  -mineral or synthetic cut fibers, characterized in that the flow of cut fibers is incorporated directly into the mixer (6) of the manufacturing and application machine and / or into the spreading device (7).  2. Manufacturing process according to claim 1 characterized in that the fibers are cut in the manufacturing and spreading machine to a length between 15 and 100 mm.  3. The manufacturing method according to claim 1 characterized in that the  dosage of fibers contained in the mixture applied to the floor is between 50 and 300 grams per square meter of surface treated.  4. Method according to claim 2 characterized in that the fibers are preferably glass fibers.  5. Device for implementing the manufacturing method according to claim 1 comprising fiber reels 10, a system for guiding the fiber strands 11, devices for cutting the fiber strands 12, dispersion systems 13, characterized in that the device produces a stream of cut fibers dispersed in the mixer 6.  6. Device according to claim 5 ensuring the constant metering of the fibers characterized in that the speed of rotation of the cutting rotor of the devices 12 is controlled by the flow of the material.