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Title:
DOUBLE LAYER DRAINING AND SOUND-ABSORBING WEARING COURSE, AND MEANS AND METHOD FOR ITS PREPARATION
Document Type and Number:
WIPO Patent Application WO/2000/055428
Kind Code:
A1
Abstract:
The present invention relates to a draining and sound-absorbing wearing course consisting of two layers having a different thickness, made up of modified bitumen and inert products having particular characteristics. This wearing course can be used for paving motor racing circuits highways, national and urban roads.

Inventors:
Italia, Paolo (Via Giovio Paolo, 11 Milan, I-20144, IT)
D'elia, Luigi (Via Fratelli Rosselli, 53 Pandino, I-26025, IT)
Da Via, Mauro (Via Scalvini, 13 Milan, I-20158, IT)
Diani, Elio (Via Trento, 1 Cassina de Pecchi, I-20060, IT)
Application Number:
PCT/EP2000/002046
Publication Date:
September 21, 2000
Filing Date:
March 08, 2000
Export Citation:
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Assignee:
AGIP PETROLI S.P.A. (Via Laurentina, 449 Rome, I-00142, IT)
ENICHEM S.P.A. (Piazza Boldrini, 1 San Donato Milanese, I-20097, IT)
Italia, Paolo (Via Giovio Paolo, 11 Milan, I-20144, IT)
D'elia, Luigi (Via Fratelli Rosselli, 53 Pandino, I-26025, IT)
Da Via, Mauro (Via Scalvini, 13 Milan, I-20158, IT)
Diani, Elio (Via Trento, 1 Cassina de Pecchi, I-20060, IT)
International Classes:
E01C7/18; E01C11/22; (IPC1-7): E01C7/18
Foreign References:
EP0381903A1
FR2768162A3
Other References:
GELDER VAN J W: "WEGENBOUWERS BEPERKEN VERKEERSLAWAAI" DE VOLKSKRANT,NL,AMSTERDAM, 8 June 1991 (1991-06-08), XP000351947
Attorney, Agent or Firm:
De Gregori, Antonella (Ing. Barzanò & Zanard Milano S.p.A. Via Borgonuovo, 10 Milan, I-20121, IT)
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Claims:
CLAIMS
1. A double layer draining and soundabsorbing wearing course consisting of: (1) an upper layer having a thickness ranging from 2 to 5 cm consisting of a bituminous conglomerate which comprises: (a) a stone aggregate consisting of elements with dimensions ranging from 0.075 to 10 mm in a quan tity ranging from 88 to 98% by weight; (b) a filler in a quantity ranging from 2 to 12% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of compo nents (a) and (b) and (2) a lower layer having a thickness ranging from 2 to 7 cm consisting of a bituminous conglomerate which comprises: (a') a stone aggregate consisting of elements with dimensions ranging from 0.125 to 20 mm in a quan tity ranging from 85 to 98% by weight; (b') a filler in a quantity ranging from 2 to 15% by weight; (c') a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of compo nents (a') and (b').
2. The wearing course according to claim 1, wherein the upper layer has a thickness ranging from 2.5 to 4 cm and consists of: (a) a stone aggregate consisting of elements with dimensions ranging from 0.075 to 7.1 mm in a quan tity of 90 to 95% by weight; (b) a filler in a quantity ranging from 5 to 10% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of compo nents (a) and (b).
3. The wearing course according to claim 1, wherein the lower layer has a thickness ranging from 3 to 7 cm and consists of: (a) a stone aggregate consisting of elements with dimensions ranging from 0.125 to 15 mm in a quan tity of 90 to 95% by weight; (b) a filler in a quantity ranging from 5 to 10% g by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of compo nents (a) and (b).
4. The wearing course according to claim 1, wherein the stone aggregates consist of healthy hard granular elements, in a nonflattened, elongated or lenticular form, clean and without foreign matter.
5. The wearing course according to claim 1, wherein the filler is selected from calcium carbonate and cement.
6. The wearing course according to claim 1, wherein the bituminous ligand is a modified bitumen con taining styrenebutadienestyrene polymers. 0.
7. The wearing course according to claim 1, wherein the lower layer is coupled with a waterproofing membrane consisting of modified bitumen saturated with grit or filler.
8. The wearing course according to claims 1 to 7, use ful for the paving of motor racing circuits, high ways, national and urban roads.
9. A bituminous conglomerate which comprises: (a) a stone aggregate consisting of elements with dimensions ranging from 0.07 to 20 mm in a quantity ranging from 85 to 98% by weight; ; (b) a filler in a quantity ranging from 2 to 15% by weight; (c) a bituminous ligand having the characteristics 0 indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of compo nents (a) and (b).
10. The bituminous conglomerate according to claim 9, useful for the preparation of the upper and lower layer of the draining and soundabsorbing wearing course according to claim 1.
11. A method for the preparation of the doublelayered draining and soundabsorbing wearing course which comprises: (i) the laying of a first lower layer having a thickness ranging from 2 to 7 cm and consisting of a bituminous conglomerate which comprises: (a') a stone aggregate consisting of elements with dimensions ranging from 0.125 to 20 mm in a quan tity ranging from 85 to 98% by weight; (b') a filler in a quantity ranging from 2 to 15% by weight; (c') a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of compo nents (a') and (b'); and (ii) the curing of this first layer; and (iii) the laying on said first layer of a second upper layer having a thickness ranging from 2 to 5 cm consisting of a bituminous conglomerate which comprises: (a) a stone aggregate consisting of elements with dimensions ranging from 0.075 to 10 mm in a quan tity ranging from 88 to 98% by weight; (b) a filler in a quantity ranging from 2 to 12% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of compo nents (a) and (b).
12. The method according to claim 11, wherein the lower layer has a thickness ranging from 3 to 7 cm and consists of: (a') a stone aggregate consisting of elements with dimensions ranging from 0.125 to 15 mm in a quan tity ranging from 90 to 95% by weight; (b') a filler in a quantity ranging from 5 to 10% by weight; (c') a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of compo nents (a') and (b').
13. The method according to claim 11, wherein the upper layer has a thickness ranging from 2.5 to 4 cm and consists of: (a) a stone aggregate consisting of elements with dimensions ranging from 0.075 to 7.1 mm in a quan tity ranging from 90 to 95% by weight; (b) a filler in a quantity ranging from 5 to 10% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of compo nents (a) and (b).
14. The method according to claim 11, wherein the lower layer is laid on a waterproofing membrane consist ing of modified bitumen saturated with grit or filler.
Description:
DOUBLE LAYER DRAINING AND SOUND-ABSORBING WEARING COURSE, AND MEANS AND METHOD FOR ITS PREPARATION.

The present invention relates to a double layer draining and sound-absorbing wearing course, its use in motor racing circuits and road paving, means and method for its preparation.

The wearing courses used in motor racing circuits, highways, national and urban roads with heavy traffic require good mechanical properties, a high grip and sur- face regularity. These properties are traditionally ob- tained using"closed"wearing courses, i. e. with reduced content of residual voids. This solution however is of no help during rainfall.

In fact, the rain stagnates on the surface with a consequent reduction in tyre grip (aquaplaning) also causing water spray which reduces the visibility.

In order to solve these drawbacks,"open"wearing courses, also called draining pavements, were developed, whose use in road paving began on a wide scale towards the mid-eighties'and was applied to highways, national and urban roads.

Draining pavements are mainly characterized by a high percentage of residual voids (>18%) obtained by adopting inert products with a discontinuous granu- lometric curve which ensures, with respect to a closed

pavements, the following advantages: -improvement in tyre grip on wet surfaces; -decrease in water spray generated by tyres in the case of rain; -elimination of aquaplaning; -reduction in the sound level outside the car owing to the absorption of acoustic energy; -reduction in the luminous reflection at night.

With respect to closed wearing courses, however, these pavements have a reduced structural resistance and a tendency towards rapid fouling, which blocks the voids and consequently reduces the draining capacity.

The use of these draining pavements consequently does not seem to be very suitable for particular appli- cations, such as for example, the paving of motor racing circuits, on which there are greater problems of struc- tural resistance and fouling.

It has now been found that the drawbacks of the known art discussed above can be overcome by the use of an open wearing course consisting of two layers have different thicknesses and different granulometric curves of the stone aggregates (inert products).

In particular, the use of modified bitumens having a reduced thermal susceptibility, high elasticity, high tack to inert products and good aging resistance, com-

bined with this double-layered structure, allows the following advantages to be obtained: (a) an improved crushing strength with respect to the traditional draining pavements; (b) a reduction in the sound impact non only externally but, surprisingly, also inside the vehicle; (c) a draining capacity which decreases more slowly with time; (d) a lesser tendency towards fouling (pore blockage).

The upper layer, in fact, obtained with stone ag- glomerates having reduced dimensions, owing to its tex- ture, acts as a sieve for the impurities present on the road surface. In this way the larger impurities are withheld on the surface without blocking the pores and can be mechanically removed by the passage of vehicles.

The finer impurities penetrate through both layers and can be easily eliminated by rain water through the larger holes of the lower layer.

In accordance with this, an objective of the pres- ent invention relates to a double layer draining and sound-absorbing wearing course made up of: (1) an upper layer having a thickness ranging from 2 to 5 cm consisting of a bituminous conglomerate which com- prises: (a) a stone aggregate consisting of elements with

dimensions ranging from 0.075 to 10 mm in a quantity ranging from 88 to 98% by weight; (b) a filler in a quantity ranging from 2 to 12% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of components (a) and (b) and (2) a lower layer having a thickness ranging from 2 to 7 cm consisting of a bituminous conglomerate which com- prises: (a') a stone aggregate consisting of elements with dimensions ranging from 0.125 to 20 mm in a quantity ranging from 85 to 98% by weight; (b') a filler in a quantity ranging from 2 to 15% by weight; (c') a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of components (a') and (b').

The upper layer of the draining and sound-absorbing wearing course preferably has a thickness ranging from 2.5 to 4 cm and consists of: (a) a stone aggregate consisting of elements with dimensions ranging from 0.075 to 7.1 mm in a quantity

ranging from 90 to 95% by weight; (b) a filler in a quantity ranging from 5 to 10% by weight; (c) a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of components (a) and (b).

The lower layer of the draining and sound-absorbing wearing course preferably has a thickness ranging from 3 to 7 cm and consists of: (a') a stone aggregate consisting of elements with dimensions ranging from 0.125 to 15 mm in a quantity ranging from 90 to 95% by weight; (b') a filler in a quantity ranging from 5 to 10% by weight; (c') a bituminous ligand having the characteristics indicated in table 2 in a quantity ranging from 4 to 5% by weight with respect to the sum of components (a') and (b').

The stone aggregates which can be used consist of healthy, hard granular elements, in a non-flattened, elongated or lenticular form, clean and without foreign matter, according to regulation C. N. R. 139/1992.

These aggregates typically have the characteristics indicated in table 1.

Table 1

P roperties Regulation Speciication Quantity of crushed product CNR 34/73 100% Weight loss (Los Angeles test) CNR 140/92 <18% Accelerated levigation coeffi-CNR 95/84 > 0. 45 cient (A.L.C.) Flattening coefficient CNR 95/84 < 1.58 Form coefficient CNR 95/84 < 3 Sensitivity to freezing CNR 80/80 < 20% Stripping in water at 40°C CNR 138/92 0% The fillers are those conventionally used for the production of conglomerates. They are generally powders with a particle size of less than 0.125 mm.

Examples of fillers suitable for the purpose of the present invention comprise calcium carbonate and cement.

The bituminous ligand is selected from modified bi- tumens having the characteristics indicated in table 2.

Table 2

Properties Regulation Specification Penetration at 25°C [0.1 mm] CNR 24/71 30-90 Softening point [°C] CNR 35/73 > 60 Fraass Breaking point [°C] CNR 43/74 <-15 Elastic flow at 25°C [%] DIN 52013 > 50 A modified bitumen having a softening point of over 80°C and an elastic flow at 25°C higher than 80%, is preferably used.

Particularly preferred is a modified bitumen con- taining SBS (styrene-butadiene-styrene) polymers ob- tained, for example, as described in U. S. patent 5,756,563, or, for example of the type sold by AGIP PETROLI S. p. A. under the trade-name of ELIFLEX.

Some of the characteristics of the pavements of the present invention are indicated in table 3.

Table 3 Properties Regulation Specific. Marshall stability CNR B. U. Nr. 30 > 7kN Marshall residual holes CNR B. U. Nr. 30 > 20% Permeability in situ-->20 1/min Cantabro weight loss (300 revs)--< 15%

The sound-absorbency characteristics, determined by means of sound level measurements, not only indicate a decrease in noise outside the vehicle, but also a reduc- tion thereof inside the vehicle of over 3 decibel.

The bituminous conglomerate, which forms a further objective of the present invention, is prepared under heating in a suitable plant by putting the stone aggre- gate, the bitumen and filler in contact with each other in the appropriate quantities.

The temperature and mixing time are generally se- lected in relation to the materials and climatic condi- tions during the laying. In any case, the mixing condi- tions are selected so as to obtain a conglomerate having an adequate laying temperature to allow effective roll- ing.

The pavement of the present invention is prepared by: (i) the laying of a first lower layer having a thick- ness ranging from 2 to 7 cm and consisting of a bitumi- nous conglomerate which comprises: (a') a stone aggregate consisting of elements with di- mensions ranging from 0.125 to 20 mm in a quantity rang- ing from 85 to 98% by weight; (b') a filler in a quantity ranging from 2 to 15% by weight;

(c') a bituminous ligand having the characteristics in- dicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of components (a') and (b'); and (ii) the curing of this first layer; and (iii) the laying on said first layer of a second upper layer having a thickness ranging from 2 to 5 cm consist- ing of a bituminous conglomerate which comprises: (a) a stone aggregate consisting of elements with di- mensions ranging from 0.075 to 10 mm in a quantity rang- ing from 88 to 98% by weight; (b) a filler in a quantity ranging from 2 to 12% by weight; (c) a bituminous ligand having the characteristics in- dicated in table 2 in a quantity ranging from 3.5 to 5.5% by weight with respect to the sum of components (a) and (b).

In practice, before proceeding with the laying of the conglomerate, all the usual operations are effected for its preparation, consisting in milling the damaged layer, profiling and cleaning.

A water-proofing membrane is then laid on top of the base layer to protect it from the infiltration of rain water.

This membrane consists of modified bitumen, pref-

erably a bitumen identical to that used for the prepara- tion of the conglomerates, suitably saturated with grit or filler.

The bituminous conglomerate is then laid on top of this membrane to obtain a first lower layer having the characteristics described above.

After laying the lower draining layer, it is advis- able to allow a curing time of not less than two days before proceeding with the laying of the upper layer.

The bituminous conglomerate is laid using slightly staggered vibratory finishers in parallel thus avoiding, or in any case reducing, longitudinal joints. These should be particularly treated (flanking and compaction) to avoid stagnation of rain or reduction in the draining capacity.

The rolling is carried out using the conventional techniques.

The draining and sound-absorbing wearing course of the present invention is particularly suitable for the paving of motor racing cirsuits and heavy traffic roads.