Lightweight coated materials and use on engineering structures

Abstract

The present invention relates to bituminous coated materials including a granular fraction and a binder, characterised in that in the granular fraction all or part of the elements are selected from among lightweight, non-absorbent aggregates with a density of less than 1.6 t/m.sup.3 and a water absorption coefficient of less than 15%. The invention also relates to the use of light, non-absorbent aggregates with a density of less than 1.6 t/m.sup.3 and a water absorption coefficient of 3% to 15% for the production of light bituminous coated materials. The invention further relates to pavements obtained by applying at least one layer of the coated materials according to the invention and to a method for applying a surface course to a surface raised above the ground which includes a step of applying coated materials according to the invention.

Claims

1. Asphalt mix comprising an aggregate fraction and a binder, the aggregate fraction comprising components with a size below 0.063 mm components with a size comprised between 0.063 and 2 mm, and components with a size comprised between 2 mm and 31.5 mm, characterized in that in the aggregate fraction, all or part of the components are light and nonabsorbent aggregates with a density between 1.1 and 1.6 t/m.sup.3 and having a water absorption coefficient below 15%.

2. Asphalt mix according to claim 1, wherein the light and nonabsorbent aggregates have a density comprised between 1.1 and 1.5 t/m.sup.3.

3. Asphalt mix according to claim 1, wherein the light and nonabsorbent aggregates have a water absorption coefficient comprised between 6 and 15%.

4. Asphalt mix according to claim 1, wherein the light and nonabsorbent aggregates are expanded slate.

5. Asphalt mix according to claim 4, wherein the light and nonabsorbent aggregates are Mayenne expanded slate.

6. Asphalt mix according to claim 1, wherein the binder content varies from 6 to 20% by weight, with regard to the total weight of the asphalt mix.

7. Asphalt mix according to claim 1, wherein the binder is a hydrocarbon binder or a plant-based binder or a synthetic binder.

8. Asphalt mix according to claim 7, wherein the binder is a hydrocarbon binder.

9. Asphalt mix according to claim 1, wherein the light and nonabsorbent aggregates have a content which varies from 60 to 100% by weight, with regard to the total weight of the aggregate fraction.

10. Asphalt mix according to claim 1, wherein said asphalt mix has a density less than 2 t/m.sup.3.

11. Asphalt mix according to claim 1, wherein said asphalt mix is resistant to rutting.

12. Asphalt mix according to claim 11, wherein said asphalt mix has a percentage of rutting after 30,000 cycles less than 7.5%.

13. Asphalt mix according to claim 1, wherein said asphalt mix is resistant to mass loss, with Cantabrian values less than 20.

14. Asphalt mix according to claim 13, wherein said asphalt mix has Cantabrian values less than 10.

15. Asphalt mix according to claim 1, wherein said asphalt mix is water resistant, with a ITSR percentage greater than 70%.

16. Asphalt mix according to claim 15, wherein said asphalt mix has a ITSR percentage greater than 80%.

17. Roadway pavement obtained by application of at least one layer of asphalt mix according to claim 1.

18. Roadway pavement according to claim 17, wherein the pavement is a surface course, an intermediate course and a base course.

19. Method for applying a surface course onto an above ground surface comprising a step of applying asphalt as defined in claim 1.

20. Method of manufacturing light asphalt mix comprising mixing a binder with light and nonabsorbent aggregates of density between 1.1 and 1.6 t/m.sup.3 and with a water absorption coefficient below 15%.

Description

EXAMPLES

Example 1

Characteristics of Light and Nonabsorbent Aggregates According to the Invention

(1) The characteristics of absorption coefficient and density for light aggregates according to the invention are compared in the following table to the characteristics of expanded clay and expanded glass.

(2) TABLE-US-00002 TABLE 2 light aggregates according to the invention Expanded Expanded uncrushed crushed clay glass Water absorption 7.7 11.0 17.6 17.9 coefficient (%) NF EN 1097-6 Absolute density 1.262 1.308 1.169 0.420 (t/m3) NF EN 1097-6

(3) Note that the light aggregates have a density comparable to that of expanded clay. In contrast, aggregates according to the invention have a significantly lower absorption coefficient than that of expanded clay or glass.

Example 2

Light Asphalt Mixes According to the Invention

(4) An example of formulation of the lightweight asphalt mix according to the invention, for an intermediate course with a 0/14 aggregate fraction and a grade 35/50 bitumen, is given in the table below:

(5) TABLE-US-00003 TABLE 3 Materials % by weight 10/14 Light aggregate (%) 31.8 4/10 Light aggregate (%) 9.1 0/2 Light aggregate (%) 27.3 0/2 Diorite (%) 18.2 Filler (%) 4.5 bitumen 35/50 (%) 9.1

(6) The mechanical properties of the asphalt mixes obtained by a hot method from this formulation are given in the table below:

(7) TABLE-US-00004 TABLE 4 True density NF EN 1267-5 (g/cm3) 1.697 PCG (NF EN 12697-31) Gyration number 100 empty (%) 10.9 ITSR (NF EN 12697-12 A) ITS air (kPa) 859 ITS water (kPa) 840 ITSR % 97.8 Rutting (NF EN 12697-22) number of cycles 30000 rutting (%) 1.9 Module (NF EN 12697-26) E* 15 C. 10 Hz (Mpa) 7059 Cantabrian mass loss at 20 C. % 5.6 (NF EN 12697-17)

(8) The mechanical properties of these asphalt mixes are compared with prepared hot asphalt mixes from the same formulation but in which the light aggregates are replaced either by vermiculite or by expanded glass. The results are given in the table below:

(9) TABLE-US-00005 TABLE 5 F1 F2 F3 0/14 0/14 0/14 lightweight lightweight lightweight asphalt mix asphalt mix asphalt mix based on based on according to TEST vermiculite expanded glass the invention NF EN 12697-22 Rutting Rutting at 30,000 6.90% >15% 1.90% cycles (%) True density of 1.752 1.79 1.697 the mix according to NF EN 12697-5 t/m3

(10) Therefore it is noted that the asphalt mixes according to the invention are light but, at the same time, have mechanical properties, in particular rutting resistance, that could not be obtained with porous rock or expanded glass.

(11) Another example of formulation of the lightweight asphalt mix according to the invention, for a binding layer with a 0/10 aggregate fraction and a grade 20/30 bitumen, is given in the table below:

(12) TABLE-US-00006 TABLE 6 Materials % by weight 4/10 Light aggregate (%) 31.4 0/4 light aggregate (%) 35.9 0/2 Diorite (%) 18.2 Filler (%) 4.5 bitumen 20/30 (%) 10.0

(13) The mechanical properties of the asphalt mixes obtained by a hot-mix method from this formulation are given in the table below:

(14) TABLE-US-00007 TABLE 7 True density NF EN 1267-5 (g/cm3) 1.697 PCG (NF EN 12697-31) Gyration number 60 empty (%) 9.7 ITSR (NF EN 12697-12 A) ITS air (kPa) 1100 ITS water (kPa) 1054 ITSR % 95.8 Rutting (NF EN 12697-22) number of cycles 30000 rutting (%) 4.2 Module (NF EN 12697-26) 9200 E* 15 C. 10 Hz (Mpa)

(15) The mechanical properties of the lightweight asphalt mix are as good as those of a conventional asphalt mix while the density of the asphalt mix is significantly lightened.

(16) Another example of formulation of the lightweight asphalt mix according to the invention, for a surface course with a 0/10 aggregate fraction and a grade 35/50 bitumen, is given in the table below:

(17) TABLE-US-00008 TABLE 8 Materials % by weight 4/10 Light aggregate (%) 49.1 0/4 Light aggregate (%) 21.8 0/2 Diorite (%) 18.2 Filler (%) 1.8 bitumen 35/50 (%) 9.1

(18) The mechanical properties of very thin asphalt concrete (VTAC) obtained from this formulation are given in the following table:

(19) TABLE-US-00009 TABLE 9 True density NF EN 1267-5 (g/cm3) 1.606 PCG (NF EN 12697-31) Gyration number 25 empty (%) 22.5 ITSR (NF EN 12697-12 A) ITS air (kPa) 752 ITS water (kPa) 684 ITSR % 91 Rutting (NF EN 12697-22) number of cycles 3000 rutting (%) 7

(20) The mechanical properties of the lightweight VTAC are as good as those of a conventional VTAC while the density of the VTAC is significantly lightened.