FR2573455A1 - PROCESS FOR OBTAINING ROAD SURFACE COATINGS BY SPREADING AQUEOUS BITUMEN EMULSIONS AND COATINGS OBTAINED - Google Patents

Abstract

THE PROCESS ALLOWS SURFACE COATINGS TO BE OBTAINED FROM AQUEOUS BITUMEN EMULSIONS. IT CONSISTS OF SPREADING, SIMULTANEOUSLY, THE EMULSION AND AN EMULSION RUPTURE AGENT, UNDER CONDITIONS SUCH AS EMULSION RUPTURE OCCURS IN THE SPREADED MASS. THE RUPTURE AGENT JET IS THEREFORE PROJECTED ON THE EMULSION BRUSH FALLING FROM THE SPREADER, IN ITS LOWER PART. THE SURFACE COATINGS OBTAINED, QUICK SET, ARE NOT FRAGILE.

Description

The present invention relates to a method for obtaining

  road surface coatings by spreading emulsion

aqueous bitumen

  The deposit of superficial coatings is an economical way

  to restore certain surface properties, including impermeability and roughness, to worn or worn road surfaces. These coatings are composed of hydrocarbon binders, rendered fluid for spreading, either in the form of aqueous emulsions or by the addition to bitumen of light fractions of petroleum distillation or

  coal. Mixtures of bitumen and hydrocarbon products

  fertilizers, known as anhydrous coatings, are spread on the soil at an elevated temperature generally between C and 160 C, while aqueous emulsions of bitumen are spread to 70 C or even at room temperature, which is a of their benefits. On the other hand, the setting of anhydrous coatings is much faster and safer than that of coatings based on aqueous emulsions, the setting of which is furthermore very influenced by the ambient temperature and humidity conditions, since in this case the setting requires the evaporation of the water, contained in the emulsion

  widespread; this phase of evaporation, which involves the rup-

  The degree of emulsion is all the more important as it determines the fixing of aggregates on the surface of the roadway. These problems have led to the preparation of bitumen emulsion surface coatings, composed of two layers, which makes it possible to return the treated pavement rapidly in circulation; it is conceivable that such

  bilayer coatings are more expensive, and it was desirable

  table to develop a process for obtaining coatings

  superficial, inexpensive, monolayers, spreadable at

  close to the ambient temperature and yet fast and safe setting, that is to say giving coatings

  not fragile, very consistent, shortly after application.

  The process for obtaining a surface coating according to

  the invention consists in spreading on the roadway simultaneously

  a conventional aqueous bituminous emulsion and a disrupting agent of said emulsion, under conditions such that the rupture of the emulsion occurs rapidly in

the spread mass.

  In order for the rupture to take place in the mass, the breaking agent can be projected on the emulsion brush falling vertically from the spreader, in the lower part of this brush, preferably in the lower half. The angle of incidence is a function of the power of the breaking agent jet, the products used and the atmospheric conditions; it is generally between 30 and 30 and will be easily adapted by the specialist to the specific characteristics of the work to be performed,

  if necessary after prior testing.

  Various agents for breaking hydrocarbon emulsions

  bures are known: their action generally results from a neutralization reaction or else from precipitation of the emulsified medium; the nature of the breaking agent depends

  essentially emulsified bitumen and emulsifier

  trusting. In the case of a cationic emulsion of higher pH,

  2.5 and containing 60 to 75% by weight of binder bitu-

  and from 0.1 to 0.5% by weight of a fatty amine hydrochloride or imidazoline emulsifier, the disrupting agent may be an aqueous solution with a concentration of between 5 and 25%, a strong inorganic base, such as sodium hydroxide, or anionic surfactant, such as a (C10-C20) alkyl sulfate, or a mixture thereof;

  the amount of solution of rupture agent projected corresponds to

  weight at 0.2 to 1% by weight of agent based on weight

of the emulsion to be treated.

  It is preferred to use a penetration bitumen 80/100, or better 180/220 (as defined by standard NF T 65-001), mixed with 5 to 15% by weight of fluid bitumen, ENGLER viscosity between O and 1; the binder content of the emulsion is preferably between 65 and 75 X

by weight and its pH greater than 3.

  The manner in which the breaking agent and the emulsion are contacted is another important feature of the process of the invention. It has indeed been found that when the rupture agent is sent onto the surface of the emulsion already deposited on the ground, the rupture phenomenon does not propagate in the mass and the setting takes place superficially, leading to forming a skin and a

poor quality coating.

  FIG. 1-A shows the preferred relative orientation of the emulsion brush E and the breaking agent jet R, with respect to the ground S. FIG. 1-B shows the previously described case of successive deposits, which causes the formation of a skin. Figure 1-C schematizes a spraying process

  which, in general, does not give

  aviable due to the disorganization of the bituminous emulsion brush falling on the ground; in this case the bursting agent jet is directed to the top of the emulsion brush, near the outlet of the spraying machine, and comes into contact

  with the brush in the upper half of it.

  The process for obtaining surface coatings based on bituminous emulsions according to the invention can be carried out under the conventional conditions of spraying

  surface coatings without the use of rup-

  ture; the speeds of the dispensing pumps of the emul-

  the spreader and its speed of advancement and the quantity of emulsion distributed over a given area need not be modified, which is another advantage of the invention, the person skilled in the art being able to to adapt the conditions of spraying the breaking agent,

  depending on the nature of the compounds used and the

specific working conditions.

  The coatings obtained by this process, characterized by rapid setting at room temperature, associated with good surface properties, are another object of the invention. In the following, we describe examples of

implementation of the invention.

Example 1

  (a) Bituminous aqueous emulsion 650 kg of a mixture comprising 600 kg of pure 180/220 bitumen (according to standard NF T-65 001) and 50 kg of 0/1 fluid bitumen are emulsified with 350 kg of an aqueous solution of a hydrochloride of a diamine (resulting from the action on 4 kg of tallow diamine, 2.6 kg of aqueous solution of HCl at 32% by weight), in a homogenizer COLAS (R) by introducing the bitumen to 130 C and the aqueous phase C. b) Breaking agent It is composed of an aqueous solution containing% by weight of sodium hydroxide and 2% by weight of

sodium lauryl sulphate.

  c) Spreading Using an emulsion ramp equipped with nozzles

  with a brush about 25 cm from the ground,

  room temperature 1.8 to 1.9 kg / m2 of the emulsion obtained according to

  (a) on the carriageway and simultaneously, from an angle of

  from 60 to 25, 50 g / m 2 of breaking agent solution

  obtained according to b); chippings 6/10 are then distributed

  tis on the ground at the rate of 8 1 / mz. The setting of the coating is at a temperature of 15 C in about 2 hours; at this time, the recirculation of the roadway can be realized. By applying the same procedure as above, a single-layer, double-grained coating with 2.1 to 2.4 kg / m2 of emulsion obtained according to a) and 7 to 9 1 / m2 of chippings 10/14 and 4 will be prepared. at 7 1 / m2 gravel 4/6; the taking will take place in 2

hours.

  EXAMPLE 2 Study of the Improvement of the Quality of the Attachment of Chippings In the laboratory, coatings of

  metal plates, by spreading the bituminous aqueous emulsion

  obtained according to Example 1-a) in the presence or absence of the breaking agent according to 1-b), and distributing on the coating obtained, according to a conventional technique, chippings (adaptation of the test of overall adhesion to the Vialit plate). The percentage of chippings remaining glued to the support metal plates was measured after their turning over, at different times after their recovery. The results obtained, which are shown in Table 1, demonstrate that the intake of the emulsion is

  much faster in the presence of breaking agent.

TABLE 1

  % setting of the emulsion at 22 ° C. * Test duration mn 0% 45% 1 hour 12% 54% 2 hours 17% 59% * measured in relation to the number of chippings remaining glued

  to the plate to the total number of chippings distributed.

Claims (4)

  1.Process for obtaining superficial coatings by spreading aqueous emulsions of bitumens, characterized in that the bituminous composition is brought into contact with an emulsion breaking agent during spraying. 2. Method according to claim 1, characterized in that the breaking agent is projected on the emulsion brush falling from the spreader, substantially in the lower half of said brush.   3. Method according to one of claims 1 or 2,   in which the bituminous aqueous emulsion comprises 60 to 75% by weight   weight of bituminous binder, and from 0.5 to 0.5% by weight of an emulsifier   cationic catalyst, characterized in that 0.2 to 1% by weight of a disrupting agent in aqueous solution selected from strong bases, anionic surfactants, is sprayed. or their mixtures.   4. Superficial pavement surface coatings, quick setting, characterized in that they are obtained by a process   according to any one of claims 1 to 3.