NZ260634A

NZ260634A - Road surfacing; production of ultrathin bituminous surface

Info

Publication number: NZ260634A
Application number: NZ26063494A
Authority: NZ
Inventors: Pierre Bense; Jean-Francois Patte; Jean-Paul Fort
Original assignee: Screg Formerly Screg Routes Et
Priority date: 1994-02-21
Filing date: 1994-05-31
Publication date: 1996-09-25
Also published as: AU669260B2; IE65353B1; FR2716470B1; FR2716470A1; IE940204A1; AU5769794A

Description

26 0 63 4 Priority 05 ats(s): Compos Class: Sp**cihca«ion R!o'1: e.ffi.l.Gr.'X.jja Publication P.O. Journal No: PATENTS FORM NO. 5 Our Refs JB203178 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION METHOD OF PRODUCING AN ULTRATHIN BITUMINOUS ROAD SURFACING We, SCREG ROUTES ET TRAVADX PUBLICS, a French Company of 1, Avenue Eugene Freyssinet-Guyancouart, 78065 St Quentin-En-Yvelines, France hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: «- 1 — (followed by page la) PT0561001 N.Z. KAT0NT Of F ICE 1 31 MAY 1994 R8CEtyi2 m 260 6 34 The present invention relates to a method of producing an ultrathin bituminous road surfacingL of the type in which at an advancing surfacing site a bituminous-binder sealing and binding layer Is applied to the road to be surfaced, and, 5 immediately after, hot coated chippings are spread over this binder 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 10 in EP-A-49,260, and the 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, the subject of the invention is a method of the 15 aforementioned type, characterized in that, at each given location on the road: (a) the ratio of the bitumen quantity contained in the bituminous-binder sealing and binding layer to the total bitumen quantity used lies between approximately 15 2 0 and 50%; (b) the bituminous surfacing has a thickness at most equal to 2.5 times the maximum size of the chippings; (c) the bituminous-binder sealing and binding 25 layer is applied in a quantity allowing metering with pure bitumen lying between 0.3 and 1.2 kg/m2 of pure binder; (d) the coated chippings are made up of chippings coated by means of a bituminous mortar consisting of sand, of fines, of possible additives, such as fibres, and of the bitumen to which an adhesion-promoting agent is possibly added; (e) the operations of application of the bituminous-binder sealing and binding layer and of spreading of the coated chippings are performed in less than 5 seconds for both operations, whereas the completion of the operation of precompactlng and smoothing. to/" with the aid of a finishing table occurs at mosl ' 3 0 seconds after the application of the binding laye (followed by page 2) |L 26 0 6 34 and (£) the speed of advance of the surfacing site lies between 5 and 30 m/min.

The method according to the invention may include one or more of the following characteristics: - the completion of the operation of precoxnpact-ing and smoothing with the aid of a finishing table occurs 10 to 30 seconds after the application of the binding layer; - the speed of advance of the surfacing site lies between 20 and 30 m/min; - the binding layer is applied in a quantity allowing metering with pure bitumen lying between 0.4 and 0.7 kg/m2; - the bitumen used in the emulsion, and possibly in the bituminous binder, is a pure bitumen modified by approximately 3% of an elastomer; - the bitumen of the binding layer is an 80/100 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer; - the bitumen of the binding layer is a 180/200 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer; - the emulsion has an Engler viscosity at 25°C (French Standard NFT 66-020) lying between 10 and 20, and contains at most 0.25% of particles of size lying between 0.16 and 0.63 mm and at most 0.10% of particles of size greater than 0.63 mm; the aggregates have a maximum size lying between 6.3 mm and 19 mm; - the aggregates have a LOS ANGELES abrasion coefficient (American Standard ASTM C 131) less than 25 for moderate traffic, less than 200 heavy lorries per day, and less them 20 for heavy traffic, greater than this value, and an accelerated polishing coefficient (French Standard NFP 18-575) greater than 50, and a flattening coefficient (French Standard NFP 18-561) less than 20 for moderate traffic, less than 200 heavy lorries per day, and less than 15 for heavy traffic, greater than 2 6 0 6 3 4 3 - this value, and a crushing index of practically 100%.

An example of implementation of the invention will now be described with regard to the appended drawing, the single figure of which represents diagram-5 statically a machine intended for the implementation of the method according to the invention.

The machine 1 shown in the drawing is self-propelled. It comprises a frame 2 mounted on several axles 3 and carrying, from the front to the rear: 10 - 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; - 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 25 the coated chippings; and - a raisable vibrating smoothing table 11 articulated onto the frame by means of two longitudinal arms 12.

For conveying the coated chippings, there are 30 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 15 which extends in a mid-position along the entire 35 length of the bottom of the box 7 as far as a chute 16 for discharging the coated chippings opposite the spreading screws 10.

In addition, as shown, it is also possible to provide, in the box 7, a levelling feed screw 17.

An electricity generator 18 has also been shown diagrammatically in the drawing, this supplying power to the heating resistance elements (not shown) o£ 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 carpet, of approximately 10 to 20 mm in thickness and, more generally, having a thickness at least equal to 2.5 times the maximum size of the chippings used, this carpet 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 surfacing requires a support which is correctly profiled and, possibly, reprofiled. This support must be clean 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 P indicated in the drawing. A succession of tip-up 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 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 tank 8, sends faux-shaped jets of this emulsion over the entire width to be surfaced, behind the rear wheels of v '■ ; the machine, forming a sealing and coated-chipping-bonding layer. The design is such that, taking into account the speed of advance of the machine, the operations of application of the bonding and sealing layer and 5 of the coated chippings are performed in less than 5 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 10 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/m2 of residual binder. 15 Installation of the surfacing is completed by conventional rolling.

The constituents used in this method will now be described in more detail. (1) Binding laver: 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 62 to 65% of residual binder after breaking the emulsion and eliminating the water. 25 The bitumen is an 80/100 or 180/220 pure bitumen, in accordance with Table I hereinbelow: TABLE I Method 80/100 180/220 * 25°C penetrability, 100 g, 5 s, 1/10 mm NFT 66-004 70-100 180-220 * Ring-and-ball softening point, °C MET 66-008 42-48 34-43 * 60°C viscosity, poise 1500±300 250±50 The fine and homogeneous emulsion is in accordance with the specifications of Table II hereinbelow: 6 0 0 - 6 -TABLE II TBST METHOD Kin Max 1.

Elastomer content of the distillation residua, % by weight 3.0 2.

Water content, % NTT 66-023 3d 3.

°C SSF viscosity 65 4.

°C Bngler viscosity NFT 66-020 . 7-day dacantation storage stability, % NFT 66-022 6.

Damulsifibility, 0.8 % sodium dioctyl sulphosuccinate, 35 ml, % ASTM D 40 7.

Charge of the particles NFT 66-021 positive 8.

Homogeneity of particles greater than 0.63 mm} particles between 0.63 mm and 0.16 mm NFT 66-016 0.10% 0.25% 9.

Breaking index NFT 66-017 110 (2) coated chippings; 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 SCKXBHS mm 4/6 6/10 6/12 19 - 100 J 100 12.7 - 100 85-100 9.5 100 85-100 -50 6.3 85-100 0-15 0-15 4.75 -50 0-10 0-10 4.00 0-15 0-3 0-3 2.36 0-3 - - 2.00 0 - 26 n* W w The properties of the chippings to be used are collated in Table IV hereinbelow: TABLE IV TESTS METHOD MODERATE TRAFFIC < 200 heavy lorries per day HEAVT TRAFFIC > 200 heavy lorries per day Los Angolas abrasion coefficient ASTM C 131 < 25 A K> O Accelerated polishing coefficient NFP 18-575 o in A > 50 Water absorption, % NFP 18-555 < 2 < 2 Flattening coefficient NFP 18-561 < 20 < 15 Crushing index 100 % 100 % Cleanliness (% exceeding 0.5 mm) < 1 < 1 Decoating test operating mode USC > 95 % > 95 % The sand used is 100 % crushed. Its sand equivalent, according to the NFP 18-598 standard, is greater than 60. Its particle size distribution 1b that o£ Table V hereinbelow: TABLE V SCKEEBS (mm) DHDERSIZE, BT 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 -40 0.15 -30 0.075 -25 260 6 34 If the sand does not contain sufficient fines, that is to say particles less than 80 /zm, fines are added, these being chosen for example, from hydrated lime, fly-ash, recovery fines and cement. These fines 5 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 10 Standards NFT 66-004 and NFT 66-008), possibly modified by an elastomer. The bitumen possesses the properties indicated in Table VI hereinbelow: TABLE VI TBST METHOD 80/100 60/70 Penetration, 25°C, 100 g, 5 a, minimum NFT 66-004 70-100 50-70 Viscosity, 60°C, poise ASTHD 3381 1,500 * 300 2,000 ± 400 Ring-and-ball softening point, °C NFT 66-008 42-48 45-51 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: 2 6 0 6 3 4 TABLE VII SIKVBS, mm " 1 LJ 1 "tu-1 ^ TOTM. UNDKRSXZK, BT WBXOBT 0/6 0/10 0/12 19 100 12.7 100 90-100 9.5 100 75-100 70-90 6.3 75-100 -45 -45 4.75 40-60 24-37 24-40 2.36 -24 21-28 21-28 2.00 18-23 18-27 18-27 00 H H -20 -23 16-26 0.60 -15 12-18 12-20 0.30 8-12 8-14 8-16 in H • o 7-10 -10 -10 0.075 -7 4-7 4-7

Claims

WHAT M7WE CLAIM IS:- - 10 - 26 0 6 3 4

1. Method of producing an ultrathin bituminous road surfacing, of the type in which at an advancing surfacing site a bituminous-binder sealing and binding layer is applied to the road to be 5 surfaced, and, immediately after, hot coated chippings are spread over this binder layer and then these coated chippings are precompacted and smoothed with the aid of a finishing table, characterized in that, at each given location on the road; 10 (a) the ratio of the bitumen quantity contained in the bituminous-binder sealing and binding layer to the total bitumen quantity used lies between approximately 15 and 50%; (b) the bituminous surfacing has a thickness at 15 most equal to 2.5 times the maximum size of the chippings; (c) the bituminous-binder sealing and binding layer is applied in a quantity allowing metering with pure bitumen lying between 0.3 and 1.2 kg/m2 of pure 20 binder; (d) the coated chippings are made up of chippings coated by means of a bituminous mortar consisting of sand, of fines, of possible additives, such as fibres, and of the bitumen to which am adhesion-promoting agent 25 is possibly added; (e) the operations of application of the bituminous-binder sealing and binding layer and of spreading of the coated chippings are performed in less than 5 seconds for both operations, whereas the com- 30 pletion of the operation of precompactlng and smoothing with the aid of a finishing table occurs at most 30 seconds after the application of the binding layer; and (f) the speed of advance of the surfacing site 35 lies between 5 and 30 m/min.

2. Method according to Claim 1, characterized in that the completion of the operation of precompactlng and. smoothing with the aid of a finishing table occurs seconds after the application of the binding layer. - 11 - 260634

3. Method according to Claim 1, characterized in that the speed of advance of the surfacing site lies between 20 and 30 m/min.

4. Method according to any one of the preceding 5 claims, characterized in that the binding layer is applied in a quantity allowing metering with pure bitumen lying between 0.4 and 0.7 kg/m2.

5. Method according to any one of the preceding claims, characterized in that the binding layer comprises an emulsion 10 of a pure bitumen modified by approximately 3% of an elastomer.

6. Method according to any one of the preceding claims, characterized in that the bitumen of the binding 15 layer is an 80/100 bitumen (French Standards NFT 66-004 and NFT 66-008) modified by an elastomer.

7. Method according to any one of Claims 1 to 5, characterized in that the bitumen of the binding layer is a 180/200 bitumen (French Standards NFT 66-004 and NFT 20 66-008) modified by an elastomer.

8. Method according to any one of the preceding claims, characterized in that the binding layer comprises an emulsion which has an Engler viscosity at 25°C (French Standard NFT 66-020) lying between 10 and 20, and contains at most 0.25 % of 25 particles of a size lying between 0.16 and 0.63 mm and at most 0.10 % of particles of a size greater than 0.63-mm.

9. Method according to any one of the preceding claims, characterized in that the chippings have a maximum size lying between 6.3 mm and 19 mm. 30

10. Method according to any one of the preceding claims, characterized in that the chippings have a Los Angeles abrasion coefficient (American Standard ASTM C 131) less than 25 for moderate traffic, less than 200 heavy lorries per day, and less than 20 for heavy traf- 35 fic, greater than this value, and an accelerated polishing coefficient (French Standard NFP 18-575) greater than 50, and a flattening coefficient (French Standard NFP 18-561) less than 20 for moderate traffic, less than 20j heavy lorries per day, and less them 15 for hea^ fi ect 12 traffic, greater than this value, and a crushing index of practically 100 %. substantially as herein described. 12. A method according to claim 1, substantially as described with reference to the accompanying drawings. 13. An ultrathin bituminous road surfacing, when produced by a method of any one of the preceding claims.

11. A method according to any one of claims 1-10, SCREG ROUTES ET TRAVAUX PUBLICS u.Andmo By Its Attorneys BALDWIN. SOU & CAREY N.Z. P'ATSjNT OFFICE • J1 MAY 1994