Bituminous compositions

Bituminous compositions are provided by mixing 100 parts of an inorganic skeleton or an aggregate with up to 7 parts of bitumen with a first modifier chosen from the group comprising styrene-butadiene polymers, styrene-isoprene polymers, recycled tires or any mixtures thereof, and a second modifier selected from the group comprising polyolefins, polyethylene terephthalate or any mixtures thereof. The present composition allows the utilization of large amounts of recycled plastics.

BACKGROUND OF THE INVENTION 
1. Field Of the Invention 
The present invention relates to asphaltic compositions for the preparation 
of bituminous draining or porous mixes and the preparation thereof. 
2. Background 
Conventional bituminous mixes are generally applied on most roads. However, 
the stresses to which these roads are subjected increase from year to 
year. Increasingly high axle loads and tire rolling pressures and the 
incessant increase in traffic have an unavoidable effect on the lifetime 
of these roads. More and more use is made of polymer-modified bitumens and 
of the development of new bituminous mix structures in order to combat the 
detrimental effects exerted by these traffic stresses. 
The main technical objectives aimed at in the use of modified bitumens are: 
(a) a greater resistance to permanent deformation; 
(b) an improved low-temperature fatigue resistance; and 
(c) an increase in the adhesive and cohesive properties. 
For many years attempts have been made in highway engineering to employ 
industrial byproducts and, among these, recovered plastics originating 
either directly from the industry or from household waste. Plastics are of 
particular interest both from the viewpoint of cost and from an ecological 
viewpoint. In fact, this application enables the plastic waste to be 
permanently removed and does not present the risks related to the possible 
presence of polluting agents in gas emissions during incineration. 
In addition to elastomeric modifiers such as SBS 
(styrene-butadiene-styrene) block copolymers or SBR (styrene-butadiene 
rubber) type or EVA (ethylene-vinyl acetate) plastomers, recent attempts 
have been made to utilize waste from cable manufacture, consisting 
essentially of LDPE (low density polyethylene) mixed with PVC (polyvinyl 
chloride) and polystyrene, or mixtures of polymers in household goods. 
European patent application number EP-332245-A, filed by Enichem having 
(i) the title "Bituminous Composition for Road Surfacing, (ii) a filing 
date of Feb. 24, 1989 and (iii) a publication date of Sep. 13, 1989 
relates to this general area. 
Bituminous draining mixes or porous asphalts have been the object of much 
interest. They are currently the preferred surfacing compositions for 
freeways and roads carrying heavy traffic. Their advantages are well known 
and include the following: 
(a) Increased safety for the users: (i) elimination of the film of water on 
the highway preserves the ;adhesion of the tires to the ground, and this 
ensures a good trajectory and efficient vehicle braking; (ii) the driver 
is no longer dazzled by the multiple reflections of the many sources of 
light; and (iii) water spraying is eliminated. 
(b) Reduction in noise: better environmental protection is obtained by 
virtue of an increase in the sound-absorption properties, in order to 
lower the perceived noise level. 
(c) Reduction in costs: increased service life of the profiling and 
foundation layers by virtue of optimum water removal by the surface 
draining layer. 
The manufacture of bituminous draining mixes calls for much care. The 
components forming part of the composition must have specific properties. 
The properties are obtained by the creation of channels within the 
thickness of the asphalt, and therefore by increasing the void volume. As 
a result of the open structure of the surface layer, the binder is 
subjected to stresses which differ from those encountered with traditional 
bituminous surface layers. The traditional compositions cannot therefore 
be employed. In order to combat these effects efficiently and therefore to 
ensure the durability of the draining layers it is necessary to have a 
sufficiently thick film of binder around each chip as well as good 
binder/granulate adhesiveness. Mechanical cohesion of the bituminous mix 
is traditionally obtained by the addition of new (SBS) or recycled (ground 
tire) elastomers, the aim being to obtain a binder which is extremely 
viscous and elastic at the service temperatures. Bituminous compositions 
in which the polyolefin concentration is higher than 5% by weight of 
bitumen give binders which are unstable in storage, greatly hardened and 
exhibiting phenomena of shrinkage on cooling. 
SUMMARY OF THE INVENTION 
The aim of the present invention is to provide an asphalt-based composition 
exhibiting the above-mentioned characteristics and permitting the massive 
use of recycled plastics such as HDPE (high density polyethylene). 
The compositions of the present invention comprise essentially: 
(a) an inorganic skeleton or aggregate comprising (by weight): from 79 to 
88 parts of macadam of 6/17 particle size (between 6 and 17 mm), from 9 to 
15 parts of sand of 0.08/2 particle size, from 3 to 8 parts of inert 
filling material of particle size smaller than 0.08, calculated to obtain 
a total of 100 parts; 
(b) from 3.5 to 7 parts by weight of bitumen which has a penetration of 
between 65 and 150 tenths of mm at 25.degree. C.; 
(c) a first modifier chosen from the group comprising styrene-butadiene or 
styrene-isoprene copolymers or a mixture of such copolymers or of recycled 
tires, in a quantity corresponding to 2 to 7% by weight, calculated on the 
mass of the bitumen, optionally extended with 0 to 3% by weight of oil, 
calculated on the mass of the bitumen; and 
(d) a second modifier chosen from the group comprising polyolefins, 
polyethylene terephthalate or a mixture of such polymers, in a quantity 
corresponding to 0.5 to 5 parts by weight:, without exceeding the quantity 
of bitumen. 
Another object of the present invention is the use of these compositions 
for the manufacture of bituminous draining mixes or porous asphalts. 
The invention further relates to a process for the preparation of 
bituminous draining mixes, this process being characterized in that the 
following are introduced into a mixer, at temperatures of between 
130.degree. and 185.degree. C., preferably approximately 140.degree. C. in 
industrial application and approximately 180.degree. C. on the laboratory 
scale: 
(a) an inorganic skeleton or aggregate comprising: 
from 79 to 88 parts of macadam of 6/17 particle size, 
from 9 to 15 parts of sand of 0.08/2 particle size, and 
from 3 to 8 parts of inert filling material of particle size smaller than 
0.08; 
(b) either 
(I) the combination of (i) bitumen which has a penetration of between 65 
and 150 tenths of mm at 25.degree. C., in a quantity corresponding to 3.5 
to 7 parts by weight, and (ii) a first modifier chosen from 
styrene-butadiene copolymers, styrene-isoprene copolymers, recycled tires 
and mixtures thereof, in a quantity corresponding to 2 to 7% by weight, 
calculated on the mass of the bitumen, optionally extended with 0 to 3% by 
weight of oil, calculated on the mass of the bitumen; or 
(II) 3.57 to 7.7% by weight, calculated on the inorganic mass, of a 
homogeneous modified bitumen-copolymer binder (styrene-butadiene or 
styrene-isoprene or a mixture of such copolymers), prepared in a vessel at 
150.degree.-180.degree. C. from the components described under (i) and 
(ii); and 
(c) a second modifier chosen from the group comprising polyolefins, 
polyethylene terephthalate and mixtures of such polymers, in a quantity 
corresponding to 0.5 to 5 parts, calculated on the inorganic mass. 
The invention also relates to the use of rolling surfaces which have water 
draining properties, characterized by the composition described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The particle size, as employed here, should be understood as meaning that 
80% , and preferably 90%, of the material must have a particle size larger 
than the lower value and 80%, and preferably 90%, a particle size smaller 
than the upper value. 
In a preferred embodiment, the invention is characterized in that it 
consists of a mixture of approximately: 
(a) 100 parts of inorganic skeleton, 
(b) 5.1 pars of bitumen, 
(c) 0.2 parts of SBS 
(d) 2 parts of HDPE, preferably recycled. 
In a preferred composition, the inorganic skeleton comprises 100 parts of: 
(a) from 81 to 85 parts of macadam of 7/14 particle size; 
(b) from 11 to 13 parts of sand of 0.08/2 particle size; and 
(c) from 4 to 6 parts of filling material of particle size smaller than 
0.08. 
The inorganic skeleton is characterized by a gap grading and must have a 
composition and a particle size to provide an in-situ void content of 
between 15 and 30%, preferably between 15 and 25%. 
The macadam must have a high hardness and a high resistance to polishing. 
The macadam which is employed for the production of such surfacings 
preferably corresponds to the following conditions: 
accelerated polishing coefficient on the 7/14 fraction &gt;45% (NBN standard 
B11-204) 
micro Deval coefficient on the 10/15 category &lt;10 (AFNOR NF standard 
P18-572 October 1978) 
Los Angeles coefficient on the 10/14 category &lt;15 (AFNOR NF standard P18573 
October 1978). 
Examples of useful macadam include flint, porphyry, quartzite and hard 
sandstone. 
The filling material may be chosen from inert matter fines with a particle 
size smaller than 0.08, such as, for example, cement, secondary crushing 
fines, fly ash, clay dust or the like. 
The bitumens are present in a proportion of 3.5 to 7 parts. The bitumens 
which can be employed for the production of such surfacings are bitumens 
for highway use, preferably distillation bitumens or reconstituted 
bitumens which have penetration values of between 65 and 150 dmm 
(according to ASTM standard D-5 or IP standard 49) and Ring and Ball 
values of between 40.degree. and 59.degree. C. (ASTM D-36 or IP 58). These 
bitumens may optionally be acidified and/or treated by the addition of 
antioxidants. The preferred bitumen grades have penetrations of between 80 
and 100 dmm (dmm=0.1 mm). 
The composition additionally comprises from 2 to 7% by weight of a 
butadiene-styrene elastomer, relative: to the bitumen (preferably 4 to 7% 
by weight). Particularly suitable copolymers include copolymers of the 
linear or radial SBR or SBS type. Styrene isoprene copolymers may aim be 
employed, for example SIS (styrene-isoprenestyrene block copolymers). 
These elastomers can be employed in new or recycled form, by themselves or 
mixed, extended with 0 to 3% of oil (oil introduced during the preparation 
of the SBS or oil incorporated during lube use of the recycled SBS in the 
form of fine rubber powder). 
Finally, the composition comprises from 0.5 to 5 parts by weight, 
preferably 0.5 to 3, relative to the inorganic skeleton or aggregate, of a 
polyolefin or of polyethylene terephthalate, alone or mixed, new or 
recycled. The polyolefin is preferably chosen from the products resulting 
from the polymerization or copolymerization of ethylene or propylene, for 
example polyethylene (high or low density), polypropylene or 
ethylene-propylene-diene copolymers (EPDM copolymers). More particularly, 
when HDPE is employed, the quantities will be preferably limited to 0.5 to 
3 parts by weight relative to the inorganic skeleton. The invention also 
makes it possible to recycle the dry packaging (plastic containers) after 
grinding. Packages soiled with aqueous or oily solutions (up to 30% by 
weight of the package) can also be employed, without preliminary washing. 
The preferred recycled product is in the form of shredded pieces of HDPE. 
In general, a bituminous draining mix or porous asphalt can be prepared 
using two different methods, the first comprising (1) mixing the macadam 
with premodified binders. This type of preparation poses the problem of 
homogeneity of the binder, which must be freshly prepared and continuously 
stirred to avoid separation, and does not allow the incorporation of large 
quantities of polyolefins. The second method (2) comprises the 
extemporaneous preparation of the composition for draining bituminous 
mixes; this type of preparation, which forms the subject of the invention, 
has the advantage of avoiding the problems of separation in storage and 
allows large quantities of polyolefins to be incorporated, provided that 
the second modifier is premetered. The order of addition of the various 
components of the composition is not important. 
The composition according to the invention has in particular the following 
advantageous properties: 
(a) increased Marshall stability; and 
(b) certain ecological impact: recycling of a large quantity of 
polyolefins. 
The direct addition of HDPE to the asphalt makes it possible to recycle up 
to 3% HDPE relative to the mass of the asphalt, which represents 20 times 
the maximum quantity employable via the modified bitumen, 
The following examples are given by way of illustration of the present 
invention and do not imply any limitation in their nature. The Marshall 
test (ASTM-D-1559-82) characterizes the properties of mechanical strength 
(stability) and plastic resistance (creep) but does not make it possible 
to measure validly all the mechanical properties of the draining asphalt, 
Only the stability measurements are significantly comparable. 
EXAMPLES 
All the experiments were conducted under the same operating conditions. The 
inorganic aggregates were screened on appropriate screens in order to 
obtain the necessary sizes and to remove adherent fine particles (wet 
screening). The inorganic aggregates were dried in the oven at 
105.degree.-110.degree. C., according to size, to constant mass. 
Individually, starting with the filling material, the necessary quantities 
of materials (in increasing nominal sizes) were weighed cumulatively with 
an accuracy of 0.5 g. The aggregate was then mixed and heated in an oven 
to a temperature of 185.degree. C. The quantity of binder or bitumen 
employed (2 kg) was heated to 180.degree. C. and introduced with an 
accuracy of 0.1 g into the blending container preheated to the blending 
temperature (170.degree. C.). The cold HDPE and the hot aggregate were 
then added. The material was mixed completely as rapidly as possible 
(maximum 135 seconds) to obtain a mix in which the bitumen was uniformly 
distributed. 
Example 1 
The bituminous mix tested corresponds to the following composition: 
(1) inorganic skeleton (corresponding to the conditions described above) 
7/14 Bande secondary crushed product: 82 parts, 
0/2 Bande secondary crushed product: 14 parts (including 1 part of fines), 
type I Ankersmit fines: 4 parts, 
(2) 5.1 parts by weight of 81)/100 bitumen 
(3) 0.2 parts by weight of Finaprene 401 powder (styrene-butadiene-styrene 
copolymer; 22% styrene), and 
(4) as the second modifying agent: 1 part by weight of dry HDPE. 
Example 2 
The composition is identical with Example 1 in the case of the inorganic 
skeleton, the bitumen and the first modifying agent, but with the addition 
of 2 parts by weight of dry HDPE. 
Example 3 
The composition is identical with Example 1 in the case of the inorganic 
skeleton, the bitumen and the first modifying agent, but with the addition 
of 1 part by weight of oily HDPE (oil content: 26.1% relative to the 
HDPE). 
Example 4 
The composition is identical with Example 3 in the case of the inorganic 
skeleton, the bitumen and the first modifying agent, but with the addition 
of 2 parts of oily HDPE. 
Comparative Example A 
The bituminous mix tested corresponds to the following composition: 
(1) inorganic skeleton: identical with Example 1, and 
(2) 5.3 parts by weight of 80/100 bitumen. There is no modifying agent. 
Comparative Example B 
The composition is identical with Example 1 in the case of the inorganic 
skeleton, the bitumen and the first modifying agent, but without the 
addition of the second modifying agent. 
Comparative Example C 
The composition is identical with Example 1 in the case of the inorganic 
skeleton, the bitumen and the first modifying agent, but with the addition 
of 03 parts by weight of cellulose as the second modifying agent. 
Comparative Example D 
The bituminous mix tested corresponds to the following composition: 
(1) inorganic skeleton: identical with Example 1, and 
(2) 5.3 parts by weight of modified bitumen made up of 91% of 80/100 
bitumen, 
6% of Finaprene (registered mark) 480 (styrene-butadiene-styrene copolymer; 
30% styrene; oil content: 50 parts per 100 parts of rubber) and 3% HDPE. 
The quantities and the results are summarized in the table below, in which: 
AD: direct addition of the SBS and modifying agent in parallel with the 
bituminous binder when coating the inorganic skeleton 
PM: polymer modified bituminous binder including the modifying agent 
prepared before the coating of the inorganic skeleton 
(*): oil content: 26.1% 
401P: Finaprene 401 powder 
480: Finaprene 480 
The results in Table 1 show that the bituminous mixes obtained according to 
the invention exhibit better use properties. 
TABLE 1 
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Marshall tests on bituminous draining mixes 
First Second 
modifying 
modifying Stability 
Process Binder 
agent agent Void % 
(kN) 
__________________________________________________________________________ 
EX 1 
AD 80/100 bit. 
Finaprene 
Dry HDPE 
21.78 
6.20 
5.1 part 
401P 1 part 
0.2 part 
EX 2 
AD 80/100 bit. 
Finaprene 
Dry HDPE 
20.80 
8.65 
5.1 part 
401P 2 parts 
0.2 part 
EX 3 
AD 80/100 bit. 
Finaprene 
Oily 21.78 
5.10 
5.1 part 
401P HDPE 
0.2 part 
1 part (*) 
EX 4 
AD 80/100 bit. 
Finaprene 
Oily 19.60 
5.55 
5.1 part 
401P HDPE 
0.2 part 
2 parts (*) 
EX A 
PM 80/100 bit. 
-- -- 21.72 
3.40 
5.3 part 
EX B 
AD 80/100 bit. 
Finaprene 
-- 22.22 
4.80 
5.1 part 
401P 
0.2 part 
EX C 
AD 80/100 bit. 
Finaprene 
Cellulose 
20.55 
4.50 
5.1 part 
401P 0.3 part 
0.2 part 
EX D 
PM Modified 
-- -- 21.84 
4.25 
bitumen 
5.3 part 
(91% 
80/100 bit.; 
6% 
Finaprene 
480; 3% 
HDPE) 
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