IE852911L

IE852911L - Road surface coatings obtained by spreading aqueous¹emulsions of bitumen

Info

Publication number: IE852911L
Application number: IE852911A
Authority: IE
Original assignee: Colas Sa
Priority date: 1984-11-21
Filing date: 1985-11-20
Publication date: 1986-05-21
Also published as: ZA858799B; GB2167975A; BE903679A; IT1201494B; IT8522825A0; ES8705066A1; MX168624B; ES549079A0; CH666924A5; FR2573455A1; LU86165A1; DE3540249C2; DE3540249A1; NZ214270A; FR2573455B1; GB8528322D0; ATA337385A; AU580114B2; CY1474A; CA1276082C

Abstract

Coatings are obtained by spreading on a surface an aqueous emulsion of bitumen and contacting this with an agent for breaking down the emulsion. [GB2167975A]

Description

10 The present Invention relates to a process for obtaining surface coatings for roads by the spreading of aqueous emulsions of bltunen.

The deposition of surface coatings Is an econonlcal neans for iaparting 15 certain surface properties, notably those of Impermeability and of ruggedness, to the road or other coatings which are used. These coatings are composed of hydrocarbon-containing binders, which are rendered fluid for spreading, either In the form of aqueous emulsions or by the addition to the bltunen of light fractions fron the 20 distillation of petroleum or of coal. The mixtures of bitumens and hydrocarbon-containing products, which are known under the name of anhydrous coatings, are spread on the ground at a high temperature which 1s generally within the range between 120°C and 160°C, while spreading of the aqueous emulsions of bitumen takes place at about 25 70°C or even at ambient temperature; this Is one of their advantages. On the other hand, the hold of the anhydrous coatings is clearly more rapid and reliable than that of the coatings based on aqueous emulsions, the hold of which is moreover Influenced to a very great extent by the ambient temperature and humidity conditions, since 30 In this case the hold necessitates the evaporation of the water contained in the emulsion which Is spread. This evaporation phase, which Involves the breakdown of the emulsion. Is all the more significant because It Influences the fixation of the aggregates to the surface of the roadway. These problems have led to the preparation of 35 surface coatings which comprise bitumen emulsion and which are composed of two layers, which permits the treated roadway to be used again rapidly for traffic; It is understood that such two-layer coatings are more costly, and It was desirable to develop a process for obtaining -Z- surface coatings which are cheap, nonolayer, spreadable at a temperature close to aiabient tenperature and nevertheless exhibiting a rapid and reliable hold, that is to say providing coatings which are non-fragile and very coherent a short tine after spreading. 5 The process for obtaining a surface coating according to the invention consists In spreading on the roadway, slnultaneously, a traditional bituninous aqueous enulslon and an agent for breaking down the said enulslon under conditions such that the breakdown of the enulsion takes 10 place rapidly within the entire spread nass.

Thus according to the invention, there Is a process for obtaining surface coating by spreading an aqueous emulsion of bltunen comprising the following steps: IS a) preparing a bituninous aqueous enulsion by enulslfying a nixture of pure bitunen of penetration 180/220 and of fluid bltunen of viscosity in the range of 0 to 1, with an aqueous solution of an alkylanine hydrochloride in a honogenlser, the bitunen being introduced at about 20 130°C and the aqueous phase at about S0°C, b) preparing an aqueous solution of a breakdown agent which is chosen fron strong nineral bases, anionic surfactants and the nixtures thereof, 25 c) spreading on a road surface with an enulslon bar equipped with jets located near the ground, at anbient tenperature, the enulsion obtained in the above step a) and slnultaneously projecting the breakdown agent solutions obtained in accordance with step b) above at an angle of incidence, or inpact, to the ground lying between 60° and 25°, 30 d) then distributing chlpplngs on the coated road surface.

In order that the breakdown should take place within the mass, it is desirable to discharge the breakdown agent onto the enulsion brush, 35 falling vertically fron 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 jet of -3- breakdown agent, the products employed and the atmospheric conditions; it is generally within the range between 10° and 30° and will be readily adapted by the specialist to the specific characteristics of the work to be undertaken, If necessary after preliminary tests. 5 Various agents for breaking down emulsions of hydrocarbons are known: their action generally results from a reaction of neutralisation or indeed of precipitation of the emulsified medium; the nature of the breakdown agent depends essentially on the emulsified bitumen and the 10 emulsifying agent. In the case of a cattionic emulsion, having a pH exceeding 2.5 and containing 60 to 75% by weight of bituminous binder and from 0.1 to 0.5% by weight of an emulsifying agent of the fatty amine or imidazoline hydrochloride type, the breakdown agent may be an aqueous solution, having a concentration within the range between 5 and 15 25%, of a strong mineral base, such as sodium hydroxide, or of an anionic surfactant, such as (C10-C2q) alkyl-sulphate, or one of the mixtures thereof; the quantity of solution of breakdown agent discharged corresponds to 0.2 to 1% by weight of agent in relation to the weight of the emulsion to be treated. 20 It is preferred to use a bitumen of penetration 180/220 (as defined by the standard NF T 65-001), 1n admixture with 5 to 15% by weight of fluid bitumen, of ENGLER viscosity within the range between 0 and 1; the content of binder In the emulsion Is preferably within the range 25 between 65 and 75% by weight, and Its pH greater than 3.

The manner 1n which the breakdown agent and the emulsion are brought Into contact is another significant characteristic of the process of the invention. It has in fact been noted that when the breakdown agent 30 1s sent to the surface of the emulsion which has already been deposited on the ground, the phenomenon of breakdown Is not propagated within the mass and the hold takes place superficially, leading to the formation of a skin and of a coating of poor quality. 35 Figure A shows the preferred relative orientation of the emulsion brush E and of the jet breakdown agent R, In relation to the ground S.

Figure B shows the case previously described of successive deposits; -4- this involves the fornation of a skin.

Figure C shows in schemtlc form a process for simultaneous spreading which, in general does not give satisfactory results because of the 5 disturbance of the brush of bituninous enulslon falling on the ground; In this case, the jet of breakdown agent Is directed towards the.upper part of the enulslon brush near the outlet of the spreader, and cones into contact with the brush In the upper half of the latter. 10 The process for obtaining surface coatings based on bituninous enulsions according to the Invention nay be Inplenented under the traditional conditions of spreading surface coatings without the use of a breakdown agent; the speeds of the punps for the distribution of the enulsion, the spreader and its speed of advancement as well as the 15 quantity of enulslon distributed on a given surface, do not need to be nodified; this is another advantage of the invention, the person skilled in the art being In a position to adapt thereto the conditions of atonlsatlon of the breakdown agent, as a function of the nature of the conpounds used and of the specific conditions of the work. 20 The coatings obtained by this process, which are characterised by a rapid hold at anbient tenperature, associated with good surface properties, are another subject of the Invention. 25 In the following, a description Is given of exanples of the inplenentation of the Invention.

Example 1 30 a) Bituninous aqueous enulslon Enulsification takes place of 650 kg of a nlxture comprising 600 kg of pure bitunen 180/220 (according to standard NF T-65-001) and 50 kg of fluid bltunen 0/1 with 350 kg of an aqueous solution of a hydrochloride 35 of a diamine (resulting fron the action on 4 kg of tallow dianine of 2.6 kg of a 32% by weight aqueous solution of HC1), in a C0LAS*Tra<'e Mar't) honogenlser, by introducing the bltunen at 130°C and the aqueous phase at 50°C. -5- b) Breakdown agent It 1s coaposed of an aqueous solution containing 10% by weight of sodlun hydroxide and 2% by weight of sodlun lauryl sulphate. 5 c) Spreading By means of an enulslon bank equipped with brush Jets and situtated at a distance of approxinately 25 cn fron the ground, spreading takes 10 place, at anblent tenperature, of 1.8 to 1.9 kg/n2 of the enulsion obtained In accordance with a) on the roadway and slnultaneously, at an angle of incidence of 60°to 25°, 50 kg/H^ of breakdown agent solution obtained In accordance with b); 6/10 chlpplngs are then distributed on the ground at a rate of 8 l/nZ. The hold of the 15 coating Is achieved at a tenperature of 15°C In approxinately 2 hours; at this tine, the resunptlon of the use of the roadway for traffic nay be undertaken. Mlth the application of the sane node of operation as previously, a monolayer coating will be prepared with double application of chlpplngs with 2.1 to 2.4 kg/n^ of enulsion 20 obtained 1n accordance with a), and 7 to 9 1/n2 of 10/14 chippings and 4 to 7 1/n2 of 4/6 chlpplngs; the hold will achieved in approxinately 2 hours.

Example gi 25 Study on the inprovenent of the quality of the fixing of the chipping Coatings of netal plates were prepared, in the laboratory, by distributing the bituninous aqueous enulslon obtained in accordance with Exanple 1-a) in the presence, or not In the presence, of the 30 breakdown agent in accordance with 1-b), and by distributing chippings on the coating obtained, In accordance with a conventional technique (adaptation of the Vlallt test of overall adhesion to the plate). The percentage of chlpplngs renalnlng attached to the netal11c support plates after the latter had been turned over was neasured at different 35 tines after covering thereof. The results obtained, which are shown In Table 1, demonstrate that the hold of the enulsion is far nore rapid in the presence of breakdown agent. -6- Duration TABLE 1 % of hold of the enulslon at 22°C* control test 1 10 30 nin 0% 45% ' 1 hour 12% 54% 2 hours 17% 59% 15 * neasured by the ratio of the nunber of chippings which renained attached to the plate to the total nunber of chippings distributed. 20 25 30 35 -7-

Claims

1. Process of surface coating by spreading an aqueous enulsion of bitunen comprising the following steps 5 a) preparing a bituninous aqueous enulslon by enulslfying a nlxture of pure bltunen of penetration 180/220 and of fluid bltunen of viscosity In the range of 0 to 1, with an aqueous solution of an alkylanlne hydrochloride In an honogenlser, the bltunen being Introduced at about 130° and the aqueous phase at about 50°C, 10 b) preparing an aqueous solution of a breakdown agent which is chosen fron strong nlneral bases, anionic surfactants and the nlxtures thereof, c) spreading on a road surface with an emulsion bar equipped with jets located near the ground, at anbient tenperature, the enulsion 15 obtained 1n the above step a) and slnultaneously projecting the breakdown agent solutions obtained in accordance with step b) above at an angle of incidence, or Inpact, to the ground lying between 60° and 25°, d) then distributing chippings on the coated road surface. 20

2. Process according to claln 1 in which step c) Involves spreading 1.0 to 2.5 kg/n2 of the aqueous enulsion and 5 to 30 gn/n2 of the breakdown agent solution. 25

3. Process according to claln 1 or claln 2 in which step d) involves spreading 6/10 chlpplngs on the coated surface at a rate of 8 1/m2.

4. Process according to any of claims 1 to 3 In which coating hardening Is achieved at a tenperature of 15°C In approxinately two 30 hours.

5. Process of road surface coating substantially as hereinbefore particularly described with reference to Figures A and B in the acconpanying drawings. 35 Dated this 20th day of Novenber 1985. -8- BY: TONKINS & CO., Ajjpmants' Agents, 5, Dartmouth Road, DUBLIN 6.