AU669260B2

AU669260B2 - Method of producing an ultrathin bituminous road surfacing

Info

Publication number: AU669260B2
Application number: AU57697/94A
Authority: AU
Inventors: Pierre Bense; Jean-Paul Fort; Jean-Francois Patte
Original assignee: SCREG SA
Current assignee: SCREG SA
Priority date: 1994-02-21
Filing date: 1994-03-09
Publication date: 1996-05-30
Anticipated expiration: 2014-03-09
Also published as: AU5769794A; NZ260634A; FR2716470A1; IE65353B1; IE940204A1; FR2716470B1

Description

AUSTRALIA 696 PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Screg -Routes- el, Travaux Publies ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys I Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Method of producing an ultrathin bituminous road surfacing flIr ii,,

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The following statement is a full description of this of performing it known to me/us:invention, including the best method la The present invention relates to a method of producing an ultrathin bituminous road surfacing, of the type in which a bituminous-binder sealing and binding layer is applied to the road to be surfaced, and, immediately after, hot coated chippings are spread over this binding layer and then these coated chippings are precompacted and smoothed with the aid of a finishing table.

The basic principle of such a method is described in EP- A-49,260, and US-A-5069578, and an object of the invention is to provide an improvement to this technique, enabling ultrathin bituminous surfacings to be obtained having a thickness which can be as low as 10 to 20 mm.

For this purpose, in accordance with the present invention there is provided method of producing an ultrathin bituminous road surfacing, in which, at an advancing surfacing site, a bituminous-binder sealing and binding layer is applied to the road to be surfaced, and, immediately after, hot coated chippings are spread over said binding layer and then said coated chippings are precompacted and smoothed with the aid of a finishing table, the coating chippings being made of chippings coated with a bituminous mortar comprising sand, fines, optional additives such as fibres, and bitumen to which an adhesion-promoting agent is optionally added, wherein, at each given location on the 25 road: the ratio of the bitumen quantity contained in the bituminous-binder sealing and binding layer to the S. total bitumen quantity in said binding layer and 0 in said coated chippings is in the range from S. 30 to S* the bituminous surfacing has a thickness at most equal to 2.5 times the maximum size of the chippings; the bituminous-binder sealing and binding layer is applied in a quantity allowing metering with from 0.3 to 1.2 kg/m 2 pure bitumen; the operations of application of the bituminous- 960325,p:\oper\phh,5769794.081,1 r i. -2binder sealing and binding layer and of spreading the coated chippings are performed in less than seconds for both operations, whereas completion of the operation of precompacting and smoothing with the aid of a finishing table occurs at most seconds after the application of the binding layer; and the speed of advance of the surfacing site is in the range from 5 to 30 m/min.

Further according to the present invention, there is provided road surfacing when applied by the method described in the immediately preceding paragraph.

The method according to the invention may include one or more of the following preferred characteristics: the completion of the operation of precompacting and smoothing with the aid of a finishing table occurs 10 to seconds after the application of the binding layer; the speed of advance of the surfacing site is in the range from 20 to 30 m/min; the binding layer is applied in a quantity allowing metering with from 0.4 to 0.7 kg/m 2 pure bitumen; the binding layer is an emulsion of pure bitumen modified by approximately 3% of an elastomer; the bitumen of the mortar is a pure bitumen 25 modified by approximately 3% of an elastomer; S" the binding layer comprises an 80/100 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an 1. elastomer; the binding layer comprises a 180/200 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer; the binding layer comprises an emulsion having an Engler viscosity at 25°C (French Standard NFT 66-020) in the range 10 to 20, and contains at most 0.25% of particles of a size in the range from 0.16 to 0.63mm and at most 0.10% of particles of a size greater than 0.63mm; the chippings having a maximum size in the range RA Nr 0 960326,p:\oper\phh,57697-94.081,2 TO -3- 6.3mm to 19mm; the chippings have a LOS ANGELES abrasion coefficient (American Standard ASTM C 131) less than 25 for moderate traffic (fewer than 200 heavy trucks per day) and less than 20 for heavy traffic (more than 200 heavy trucks per day), an accelerated polishing coefficient (French Standard NFP 18-575) greater than 50, a flattening coefficient (French Standard NFP 18-561) less than 20 for moderate traffic (fewer than 200 heavy trucks per day) and less than 15 for heavy traffic, (more than 200 heavy trucks per day) and a crushing index of approximately 100%.

An embodiment of the implementation of the invention will now be described, by way of example only, with regard to the appended drawing, the single figure of which represents diagrammatically a machine intended for the implementation of the method according to the invention.

The machine 1 shown in the drawing is selfpropelled. It comprises a frame 2 mounted on several axles 3 and carrying, from the front to the rear: an idler roller 4, of horizontal and transverse axis, which serves to push a tip-up lorry for supplying coated chippings; a hopper 5 for receiving the coated chippings; a control cabin 6; S- an intermediate box 7 for the buffer-storage of the coated chippings; an emulsion tank 8; an emulsion spray boom 9, of width which can be adjusted by virtue of a telescopic structure. This boom comprises a series of spray nozzles, each of which includes an unblocking needle connected to means of actuation (not shown), for example by manual control or under the control of a blockage detector (not shown); two feed screws 10 for transverse spreading of the coated chippings; and hRA4 NT OA "960326,p:\oper\phh,57697-94.081,3 I 1 3a a raisable vibrating smoothing table 11 articulated onto the frame by means of two longitudinal arms 12.

For conveying the coated chippings, there are provided a first feed screw 13, surrounded by a cylindrical casing 14, the axis of which rises up from the bottom of the hopper 5 and which emerges, at its upper part, in the box 7, and a second, horizontal, feed screw which extends in a mid-position along the entire length of the bottom of the box 7 as far as a chute 16 for discharging the coated chippings opposite the spreading screws In addition, as shown, it is also possible to provide, in the box 7, a levelling feed screw 17.

0 *S Se o Mv ee 0 T, ai 4 An electricity generator 18 has also been shown diagrammatically in the drawing, this supplying power to -the-heating resistance elements (not shown) of the box 7, the tank 8 and the feed screws 13, 15 and 17.

A description will now be given of the installation, in a single pass and at high speed, by means of the machine 1, of an ultrathin bituminous e, of approximately 10 to 20 mm in thickness and, more generally, having a thickness at -lea-s- equal to 2.5 times the maximum size of the chippings used, this Jeape-4 ensuring, in a long-lasting manner, adhesion and impermeability and a low running noise. The main application of this method is the repair of roads, the adhesion and impermeability of which it is desired to restore, but it may also be used as surfacing for a new road. The surfacing can be used for all types of road traffic.

By reason of its very small thickness, the o: surfacing requires a support which is correctly profiled and, possibly, reprofiled. This support must be clean E 20 and, beforehand, swept and exposed to suction.

During the operation of the machine, the latter advances at a constant speed of from 5 to 30 m/min, and preferably from 20 to 30 m/min, in the direction of the arrow F indicated in the drawing. A succession of tip-up 25 lorries (not shown) discharge, into the hopper 5, hot coated chippings, at a temperature from 160 to 180°C, these tip-up lorries being pushed by the roller 4.

The screw 13 conveys these coated chippings into the buffer-box 7, from where they are conveyed by the 30 screw 15 right into the chute 16, which discharges them in front of the inside ends of the screws 10. The latter spread out the coated chippings laterally, and the surfacing is compacted and smoothed by the table 11. If a major build-up of coated chippings occurs in the box 7, levelling may be carried out by means of the screw 17.

Just in front of the lower end of the chute 16, the boom 9, supplied with bituminous emulsion via the A tank 8, sends fan-shaped jets of this emulsion over the entire width to be surfaced, behind the rear wheels of r r r 5 the machine, forming a sealing and coated-chippingbinding layer. The design is such that, taking into account the speed of advance of the machine, the operations of application of the binding and sealing layer and of the coated chippings are performed in less than seconds for both operations. Thus, the hot coated chippings instantly bring the emulsion to the boil, before it could be broken, the sudden rise in the temperature causing the breaking of the emulsion to be accelerated. This ensures strong adhesion, according to the teaching of the aforementioned EP-A-49,260.

The metering with residual pure binder depends on the texture and on the porosity of the support: it varies from 0.3 to 1.2 kg/m 2 of residual binder.

Installation of the surfacing is completed by conventional rolling. ,escr6e The constituents used in this method will now be pi~ned 1 0oo d-oribed- in more detail.

Binding layer: 20 This binding layer is a cationic bitumen emulsion consisting of a bituminous binder, which is a bitumen modified by at least 3% of a latex or of an SBS copolymer, in water, with 6' to 65% of residual binder after breaking the emulsion and eliminating the water.

The bitumen is an 80/100 or 180/220 pure bitumen, in accordance with Table I hereinbelow: TABLE I o Method 80/100 180/220 25 0 C penetrability, NFT 66-004 70-100 180-220 100 g, 5 s, 1/10 mm Ring-and-ball softening NFT 66-008 42-48 34-43 point, °C 60 0 C viscosity, poise 1500±300 250±50 The fine and homogeneous emulsion is in accordance with the specifications of Table II hereinbelow: r r' r 6- .1 TABLE II TEST METHOD Mini Max 1. Elastomer contenrt of the distillation vesidue, by 2. Water content, %NFT 66-023 35 39 3. 25WC SSF viscosity 20 4. 25 0 C Engler viscosity NFT 66-020 10 7-day decantation storage NFT 66-022 stability, 6. Demulsifibility, 0.8 %ASTM D sodium dioctyl suiphosucounate, 35 ml, 7. Charge of the particles NFT 66-021 positive 8. Homogeneity of particles NFT 66-016 0.10% greater than 0.63 mm; 0.25% particles between 0.63 mm and_0.16_mm 9. Breaking idex NFT 66-017 _110_J 20 Bitumen-coated chippinrs: The bitumen-coated chippings comprise, on the one hand, chippings and, on the other hand, a coating mortar consisting of crushed sand, possibly of added fines, and of a bituminous binder.

The chippings most commonly used are 4/6, 6/10 or 6/12 chippings, with the particle size distributions of Table III hereinbelow: TABLE III SCREENS Mm 4/6 6/10 6/12 19 j 100 100 12.7 -100 85-100 100 85-100 25-50 6.3 85-100 0-15 0-15 4.75 25-50 0-10 0-10 4.00 0-15 0-3 0-3 2.36* 0-3 S 2.00 0 AI At -7 The properties of the chippings to be used are collated in Table IV hereinbelow: TABLE IV TESTS METHOD MODEaTE TRPAFFIC HEAVY TRAFFIC 200 heavy 200 heavy lorries per day lorries par day Los Angeles ASTN C 131 25 abrasion coefficient Accelerated NFP 18-575 50 polishing coefficient Water NFP 18-555 2 2 absorption, Flattening NFP 18-561 20 coefficient Crushing index 100 Cleanliness 1 1 exceeding 0. 5 mm)III Decoating test oeaig 95

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The sand used is 100 crushed. Its sand equivalent, according to the NFP 18-598 standard, is greater than 60. Its particle size distribution is that of Table V hereinbelow: TABLE V SCREENS (im) UNDERSIZE, BY WEIGHT 4.75 100 4.00 100 2.36 90-100 2.00 85-95 1.18 60-80 0.60 45-60 0.30 30-40 0.15 20-30 0.075 ____15-25 0*.0 8 If the sand does not contain sufficient fines, that is to say particles less than 80 pm, fines are added, these being chosen for example, from hydrated lime, fly-ash, recovery fines and cement. These fines will all have a size less than 0.15 mm, with 80 passing through the 75 m screen.

The coating bitumen, depending on the climatic conditions and the intensity of the traffic, is preferably an 80/100 or 60/70 pure bitumen (French Standards NFT 66-004 and NFT 66-008), possibly modified by an elastomer. The bitumen possesses the properties indicated in Table VI hereiubelow: I TABLE VI 1 15 i i i TEST METHOD 80/100 60/70 Penetration, 25°C, 100 :FT 66-004 70-100 50-70 g, 5 s, minimum Viscosity, 60 0 C, poise ASTM D 3381 1,500 300 2,000 t 400 Ring-and-ball softening NFT 66-008 42-48 45-51 point, °C The mixture, namely the coated chippings feeding the machine, contain approximately 5.2 of bitumen with respect to the total weight of the dry materials. Its particle size distribution is provided by Table VII hereinbelow: i All -9- TABLE VII SIEVES, anTOTAL UNDERSIZE, BY WEIGHT 0/10 0/12 19 -100 12.7 90-100 100 75-100 70-90 6.3 75-100 30-45 30-45 4.75 40-60 24-37 24-40 2.36 20-24 21-28 21-28 2.00 18-23 18-27 18-27 1.18 15-20 15-23 16-26 0.60 10-15 12-18 12-20 0.30 8-12 8-14 8-16 0.15 7-10 5-10 5-10 0.075 5-7 4-7 4-7 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "1comprise", or variations such as "comprises" or 'icomprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

960325,p:\oper\pbh,57697-94.081,9 C C~ C CC C C

Claims

2. Method according to claim 1, wherein the completion of the operation of precompacting and smoothing with the aid of RA 96032p:\oper\pb 99.0811 960325,p:\oper\ph,57697-94.081,10 TO| -11 a finishing table occurs 10-30 seconds after the application of the binding layer.
3. Method according to claim 1 or claim 2, wherein the speed of advance of the surfacing site is in the range from to 30 m/min.
4. Method according to any one of the preceding claims, wherein the binding layer is applied in a quantity allowing metering with from 0.4 to 0.7 kg/m 2 pure bitumen. Method according to any one of the preceding claims, wherein the binding layer is an emulsion of pure bitumen modified by approximately 3% of an elastomer.
6. Method according to any one of the preceding claims wherein the bitumen of said mortar is a pure bitumen modified by approximately 3% of an elastomer.
7. Method according to any one of the preceding claims, wherein the binding layer comprises an 80/100 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer.
8. Method according to any one of claims 1 to 6, wherein the binding layer comprises a 180/200 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer.
9. Method according to any one of the preceding claims, i, wherein the binding layer comprises an emulsion having an Engler viscosity at 25 0 C (French Standard NFT 66-020) in the I" range 10 to 20, an6 contains at most 0.25% of particles of a size in the range from 0.16 to 0.63mm and at most 0.10% of particles of a size greater than 0.63mm.
10. Method according to any one of the preceding claims, C t Method according to any one of the preceding claims, W 960325,p:\opcr\ph,57697-94.081,11 a c. -12- wherein the chippings have a maximum size in the range 6.3mm to 19mm.
11. Method according to any one of the preceding claims, wherein the chippings have a Los Angeles abrasion coefficient (American Standard ASTM C 131) less than 25 for moderate traffic (fewer than 200 heavy trucks per day) and less than for heavy traffic (more than 200 heavy trucks per day), an accelerated polishing coefficient (French Standard NFP 18- 575) greater than 50, a flattening coefficient (French Standard NFP 18-561) less than 20 for moderate traffic (fewer than 200 heavy trucks per day) and less than 15 for heavy traffic (more than 200 heavy trucks per day), and a crushing index of approximately 100%. 11. Method of producing a bituminous road surfacing substantially as hereinbefore described with reference to the drawing and/or Examples.
12. Road surfacing when applied by the method claimed in any one of the preceding claims. DATED this 26th day of March, 1996. SCREG ROUTES ET TRAVAUX PUBLICS By their Patent Attorneys DAVIES COLLISON CAVE 4 t 4 e4 t I t 960325,p:\oper\ph,57697-94.081,12 -i Ui 2 Method of producing an ultrathin bituminous road surfacing ABSTRACT 0 oa~o errr 00 00 o 09 OFO 00 0 0 0 II 00 0 O The method described consists in spreading a thick layer of bituminous binder and then, immediately after, in applying coated chippings, which enables an ultrathin road surfacing to be obtained, the thickness of which is at most equal to 2.5 times the maximum size of the chippings. Single figure 0 *o a a at 0**a I-