WO1993011302A1 - Phosphorescent bituminous composition - Google Patents

Abstract

Phosphorescent bituminous composition for use as a road surface material. Phosphorescent plastics or resins are added to conventional bituminous paving in order to facilitate night-time driving or driving with reduced visibility. The phosphorescent plastics or resins feature several colours and can be incorporated either during preparation of the bitumen or by spraying and pressing onto a surface which has just been covered with bitumen.

Description

 PHOSPHORESCENT BITUMINOUS COMPOSITION

 The present invention is characterized by the association of one or more phosphorescent compounds with a hydrocarbon binder emulsion.

 The bituminous compositions thus obtained can be used for coatings on circulated surfaces.

 Poor visibility of the roadway currently remains a major accident factor, often aggravated by used or absent markings on the ground.

 The black color of bitumen favors piloting errors at night, due to the risk of confusion and poor contrast with the surrounding environment.

 To overcome these drawbacks, this invention proposes incorporating phosphorescent composites themselves included in a plastic or synthetic resin support, into the bituminous binder emulsion in order to

 to achieve phosphorescence at the top of the bitumen.

 The phosphorescence will be weakly perceived during the daytime periods while it will make it possible to distinguish the circulated surfaces

 very effectively during night or visibility periods

 reduced (fog) ..

 Thus, it will become easier to perceive a change of direction, a narrowed roadway, as well as immobile obstacles.

 on the road which can be seen because they then mask the phosphorescent area on which they rest.

 This invention contributes to improving the safety of the road network.

The phosphorescent compounds will preferably be incorporated into synthetic materials, plastics or resins in order to ensure optimum light profitability according to the desired use. The intensity of the phosphorescence can be modulated according to the amount of active phosphorescent product contained in the synthetic support. This intensity can also be adjusted as a function of the number of active phosphorescent elements spread per square meter of coated pavement.

 This flexibility of use makes it possible to adapt the coating according to local needs: (example; The coating of a tunnel must provide optimum brightness.)

 In order to avoid a homogeneous distribution of the elements

 phosphorescent in the thickness of the bituminous layer, (because only the surface phosphorescent elements are useful), it is advisable to use a plastic or a resin whose density is lower than that of bitumen, which will facilitate during spreading the supernatant effect of these useful elements.

 This precaution is not essential on the other hand when the gravel is simply sprayed on the surface of the bitumen. It is then sufficient to homogeneously mix the phosphorescent elements with the gravel usually used.

 The good adhesion of phosphorescent elements with their bituminous binder is ensured thanks to the rough surfaces of phosphorescent plastics; the shape of these plastics should be as close as possible to the cubic shape to ensure good maintenance of the coating.

 The calibration of phosphorescent plastics will be adapted to a. that of the gravel used jointly.

 The hardness and the adhesion of the phosphorescent plastic can vary on demand according to the use of the roadway in order to correspond to the mechanical and thermal stresses undergone over time.

In order to maintain the above qualities, it is desirable that the melting temperature of the phosphorescent plastic is significantly higher than the temperature of preparation or spreading of the hydrocarbon binder, (the flash point must generally be greater than 180 degrees)

 The reactivation of the phosphorescent compound must be carried out after a short light exposure. Lighting time

 of a car traveling at 90KM / H on a phosphorescent road should be used as a reference.

 The phosphors can be mixed according to their sensitivity to ensure correct light emission taking into account the ambient light.

 The phosphorescent agents and their supports must be chemically compatible with the hydrocarbon binder emulsion to avoid a side reaction.

 The invention makes it possible to meet current needs

due to the great diversity obtained by plastics and

phosphorescent resins detailed previously.

 In the following, examples of the composition according to the invention and the results of their use are described.

 In the case where the quantity of bituminous composition

phosphorescent to prepare is relatively low, of the order of

spreader, for example, the phosphorescent agent is preferably introduced into the tank at the time of unloading. The mixture is then stirred so that the final composition is homogeneous. The lower density of the phosphorescent agent will allow it to float during spreading.

In the case of spreading of gravel on bituminous layer it is preferable to distribute the phosphorescent agents uniformly using a mixer or any other suitable material, in order to obtain a surface spread corresponding to the number of phosphorescent elements desired per square meter of surface covered (30 phosphorescent elements per square meter offer a significant difference in visibility)

 The road properties of the coatings thus produced were compared with those of the control coatings according to conventional procedures. These tests did not reveal any significant differences, except for luminescence.

 In the example chosen, phosphorescent plastics

 represent 0.5% by mass of the final coating. This value can vary more or less depending on the phosphorescent product used and the use of the coating. This is only an indicative value for this example.

 The main interest of this invention is to ensure better visibility and mainly facilitates driving at night.

 These easily adjustable application conditions must allow

 obtain a satisfactory brightness taking into account the needs

 specific to the road section considered.

 The road properties of the coatings obtained can also be modified in the direction of better adhesion and less rapid wear thanks to the intrinsic mechanical properties of phosphorescent resins.

 The invention seeks to obtain a ratio (number of particles used / number of effective particles) very close to unity, in order to ensure a minimum cost of use. However, the repercussion of this invention in terms of health savings will largely compensate for the low additional cost of implementation.

 Several phosphorescent colors are currently available (green, yellow, pink, blue, orange ...). In order to ensure standardized use, it seems interesting to reserve certain colors for previously defined road sections; for example :

(green; national roads - yellow; motorways - pink; departmental roads orange; crossroads or hazardous areas.)

 The percentage of nighttime accidents compared to daytime accidents varies from region to region from 25 to 60%. However, night road traffic is ten times less than day traffic.

 This number of nighttime accidents when compared to actual traffic becomes very high. The improvement in visibility conditions ensured by the invention will make it possible to reduce the number and save human lives ...

Claims

 1. Bituminous composition for coating surfaces  circulated comprising, a hydrocarbon binder and gravel, characterized in that it also contains phosphorescent compounds included in plastic supports or resins.  2. Composition according to Claim 1, characterized in that  that the phosphorescent products used can provide phosphorescence of several colors depending on the additives used.  3. Composition according to Claim 1, characterized in that the plastics and resins in which the products will be included  phosphorescent must have physico-chemical characteristics compatible with the mechanical and thermal stresses supported.  4. Process for the preparation of a bituminous composition according to claim 1, characterized in that the plastics or phosphorescent resins with hydrocarbon binder in preparation  or by spraying them on a surface which has just been coated with bitumen.  5. Surface coating, characterized in that they result from the application of a bituminous composition according to any one of claims 1 to 3.