MXPA06003946A - Method of manufacturing a bituminous coated material - Google Patents

Abstract

The method comprises a stage of drying of the granular materials followed by a stage of coating of the whole thereof with a hot bituminous binder. According to the invention, the drying stage is carried out in conditions which allow a fraction of the initial humidity of the granular materials to remain. The invention has application in road building.

Description

PROCEDURE TO MANUFACTURE A BITUMINOUS COATING DESCRIPTIVE MEMORY The invention relates to a process for manufacturing a coating comprising solid fragments coated with a binder, the process comprising a step of drying the solid fragments followed by a step of coating all of the solid fragments with binder, in particular with hot binder By "solid fragments" are meant in this specification all those solid fragments usable for the production of coatings, particularly for the construction of roads, which particularly comprise natural mineral granules, and the aggregates of coatings resulting from the recycling of the materials recovered during the repair of the roads. By "binder" is meant any hydrocarbon binder of fossil or vegetable origin used for the production of coatings, in particular pure bitumen or addition of fluxes and / or fluidifiers and / or modified by the addition of polymers, this binder possibly being presented in the form of an emulsion or a foam. In the conventional hot coating process, the drying step is carried out in such a way that the humidity of the granules is substantially eliminated, which requires a considerable energy consumption due to the large amount of water initially contained in the granules. granulated In addition, the drying and the increase of temperature entail a release of fumes containing steam loaded with powders. Given their large quantity, these fumes are difficult to treat and the carrying out of the process therefore entails a considerable contamination of the environment. In order to solve this problem, EP 1 469 038 A proposes to carry out the drying step on a first part of the granulates, substantially devoid of fines, to coat this first part with hot bitumen, and then to add to the mixture thus obtained a second part. part of the granulates, comprising sands and fines. This process requires having two fractions of granules, one of which is free of fines while the other contains fines, which can involve difficulties. In addition, this process can not be performed effectively in certain existing coating installations, and may therefore require costly packaging thereof. The object of the invention is to eliminate totally or in part these drawbacks. The invention particularly contemplates a process of the kind defined in the introduction, and provides that the drying step is carried out under conditions that allow a fraction of the initial moisture of the solid fragments to subsist.

Optional features of the invention, complementary or replacement, are listed below: - The drying stage concerns only a first part of the solid fragments, which is then mixed, before the coating step, with the remaining part that It has retained its initial humidity. - The drying step is carried out at a temperature higher than 100 ° C, preferably at a temperature of approximately 130 ° C. - The upper limit of the granulometry of said remaining part is less, equal to or greater than the upper limit of the granulometry of said first part. - The upper limit of the granulometry of said remaining part is less than or equal to the lower limit of the granulometry of said first part. - The granulometry of said remaining part is selected between 0/2 and 0/4. - The drying stage concerns the totality of the solid fragments and is carried out under conditions that allow a fraction of the humidity of these to subsist. - The drying step is carried out at a temperature lower than 100 ° C, preferably at a temperature of approximately 90 ° C. - A controlled amount of water is added to the solid fragments between the drying and coating steps and / or after the coating step.

The binder is used at a temperature between 100 and 200 ° C, preferably around 160 ° C, or between 30 and 90 ° C in the case of a binder in the form of an emulsion. In a variant of the process according to the invention, the drying step concerns only a first part of the solid fragments, which is then coated, after which the remaining part, which has retained its initial moisture, is added to the mixture obtained, containing at least the first part thin. The invention is illustrated below by examples. In these examples, the solid fragments are mineral granules with a grain size of 0/10 mm, the binder is a bitumen of penetrability 35/50 according to the norm NF EN 1426, and the drying is carried out at 130 ° C when it concerns only to a first part of the granulates and to 90 ° C when it concerns all the granulates. The proportions indicated are by weight.

EXAMPLE 1 The solid fragments consist of 98% granules with a grain size of 0/10 mm and 2% of calcareous fines. 98% of 0/10 granules are porphyry and have the following particle size distribution: 2/6 22 0/2 32 Fractions 6/10 and 2/6 and the fines are mixed and dried at 130 ° C, then from which the fraction 0/2, whose moisture content is 4%, is added to the room temperature. Then 5.6% bitumen 35/50 is introduced at 160 ° C to make the coating.

EXAMPLE 2 The composition of the solid fragments and the amount of binder are the same as in Example 1. The drying is carried out on all the solid fragments, after which 1.5% of water is added in relation to the mass of these, before coating by introduction of the binder at 160 ° C.

EXAMPLE 3 The nature and the granulometric distribution of the solid fragments and the amount of binder are the same as in Examples 1 and 2. The whole of the solid fragments is divided homogeneously into a first part representing 65% by weight and a second part. part representing 35% by weight. The first part is dried at 130 ° C, and the second part, whose humidity rate is 4%, is then added at room temperature. Then 5.6% bitumen 35/50 is introduced at 160 ° C to make the coating.

EXAMPLE 4 The nature and the granulometric distribution of the solid fragments and the amount of binder are the same as in Examples 1, 2 and 3. The group of the solid fragments is divided homogeneously into a first part representing 80% by weight and a second part representing 20% by weight. The drying is carried out on the first part, which is then coated with the binder introduced at 160 ° C, after which the second part which is at room temperature and which has a moisture content of 4% is added.

EXAMPLE 5 In this example, the solid fragments are composed by weight by 2% of calcareous fines, as in the previous examples, and 98% of silicate-calcareous granules with a grain size of 0/10 mm, with the granulometric distribution of the latter as follows: / 10 29 4/6 28 The procedure is as in Example 3, except that the two parts of the solid fragments do not have the same granulometric composition, the first part comprising all of the fractions 6/10 and 4/6 and fines and fractions. a proportional part of the fraction 0/4 that corresponds to 16% of the total of the solid fragments, the second part being constituted by the remaining 25% of the fraction 0/4, which has a moisture content of 4%. On the other hand, the amount of binder reaches 5.9% of the mass of the solid fragments. The following table gives for each of the examples the final temperature of the coating and various characteristics of it. As a comparison, corresponding data are provided for reference coatings obtained from the same components by the conventional method of drying all of the solid fragments at 160 ° C before coating.

In the chart: - "PCG temperature" represents the temperature in ° C at which the coating is carried to perform the PCG test according to the French standard P 98-252, - "PCG%" represents the percentage of holes, obtained for 60 turns during the test on the rotary shear press (PCG) according to the French standard P 98-252, - "% water" represents the water content by weight of the coating at the end of the coating, - "% of voids" represents the Initial hole percentage of the test piece subjected to the rutting test, - "Rust formation" represents the percentage of holes after 30,000 cycles in the rutting test according to the French standard P 98-253-1, - " r / R "represent the ratio r / R obtained in the Duriez test according to the French standard P 98-251-1.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. A method for manufacturing a coating comprising solid fragments coated with a binder, the process is characterized in that it comprises a step of drying the solid fragments followed by a coating step by exclusively adding a binder to all of the solid fragments, the Drying stage is carried out under conditions that allow a fraction of the initial moisture of the solid fragments to subsist. The method according to claim 1, further characterized in that the drying step concerns only a first part of the solid fragments, which is then mixed before the coating step, with the remaining part which has retained its initial humidity. The method according to claim 2, further characterized in that the drying step is carried out at a temperature higher than 100 ° C, preferably at a temperature of approximately 130 ° C. 4. The process according to claim 1, further characterized in that the drying step concerns all of the solid fragments and is carried out under conditions that allow a fraction of the humidity thereof to subsist. 5. The method according to claim 4, further characterized in that the drying step is carried out at a temperature of less than 100 ° C, preferably at a temperature of approximately 90 ° C. The process according to any of the preceding claims, further characterized in that a controlled amount of water is added to the solid fragments between the drying and coating steps and / or after the coating step. The method according to any of the preceding claims, further characterized in that the binder is of fossil or vegetable origin. The method according to any of the preceding claims, further characterized in that the binder is used at a temperature comprised between 100 and 200 ° C, preferably of approximately 160 ° C, or between 30 and 90 ° C in the case of a binder in the form of an emulsion.