FR2721952A1 - ASPHALT COULE ARME - Google Patents

Abstract

The invention relates to the field of mastic asphalt. The reinforced mastic asphalt according to the invention, of the type comprising a binder consisting of bitumen, filler, sand and gravel, obtained by hot mixing between 200 and 250deg. approximately, is essentially characterized by the fact that its formulation contains 0.1 to 2% by weight relative to the binder of short glass fibers, the size of which exhibits softening at the mixing temperatures of the binder, so as to release the strands constituting said fibers.Application to the production of waterproofing and road coverings.

Description

The present invention relates to formulations

  poured and reinforced asphalt by means of a charge

  both improve certain mechanical properties, especially at low temperatures. The invention further covers applications of said formulations in the form

coatings.

  We know that mastic asphalts are made up of hot mixtures of bitumen, filler,

  sand and gravel, in proportions that character-

  cherish the application for which they are intended, for example building waterproofing, parking or deck waterproofing, or simply road surface layer. Poured asphalts are used by

  hot pouring and usually without any reinforcement.

  However, we looked for additional per-

  mechanical training by the use of reinforcements, such as a glass cloth, a glass veil or a glass grid, or even a metallic mesh, such a known technique having been used by various users. However, the reinforcement effect thus obtained is exerted substantially in a single plane, preventing the obtaining of homogeneous properties which would in particular be required in the case of coatings subjected to mechanical stresses at low temperatures. Furthermore, fillers of glass fibers have been incorporated into asphalt, but only for the purpose of strengthening the retention between them of gravel forming the essential mass of said asphalt, which is a material of formulation very different from that of poured asphalt and which is implemented by compaction instead of being implemented by pouring like poured asphalts. The present invention therefore aims to remedy the

  disadvantages above, providing the formu-

  lations of mastic asphalts comprising a reinforcement producing its effects in almost all directions instead of producing them only in a direction parallel to the coating, producing its effects throughout the mass of the coating instead of producing them only in a single plane and imparting especially with asphalts better resistance to hot punching without the need for incorporation

  hardener, while improving the characteristics

  maintenance of elasticity at low temperatures, particularly suitable for carrying out

waterproof coatings.

  According to the invention, a poured asphalt formulation comprising a binder consisting of bitumen, filler, sand and gravel obtained by hot mixing between 200 and 250 C approximately, contains from 0.1 to 2% by weight. compared to the fiber binder

  short glasses whose size is likely to pre-

  feel a softening at the binder mixing temperatures, so as to release the constituent wires

fibers.

  Advantageously, the glass fibers pre-

  feel a length of about 25 mm for a diameter of about 24 g and consist of at least 10 elementary wires.

  Other features and advantages of the

  vention will emerge better from the description which goes

  follow, made next to the attached drawings on the-

which:

  Figure 1 shows a traction-

  comparative break of four mastic asphalt formulations;

  Figure 2 shows a traction-

  comparative break of two formulations whose indenta-

  tion is different; FIG. 3 represents a comparative graph of the indentation as a function of the bitumen content / 50 in the total binder of formulations according to the invention; and FIG. 4 represents a comparative graph of the workability index as a function of the bitumen content according to FIG. 3. The Applicant has determined in the course of its work that the reinforcement effect being exerted in almost all directions and acting throughout the mass of the coating is obtained by means of the elementary wires of a filler of short glass fibers, that is to say of a length between 12 and 50 mm, preferably 25 mm , and each composed of at least 10 elementary wires which ensure the desired homogeneity effect. However, the release of these elementary threads within the binder at its mixing temperature of between 200 and 250 C requires a

  size softening in this temperature range

  res, which is not the case for example of glass fibers intended for thermal insulation. Given these imperatives, including those influencing the cost price and the ease of implementation, the Applicant has defined a type of fiber which is close to certain textile fibers, an example of which is those used in the trade under the name VETROTEX, in particular the so-called quality

  P 103/25 which corresponds substantially to the characteristics

  that the Applicant considers necessary to obtain

tion of the desired properties.

  The Applicant has found that the addition of this type of glass fiber in the asphalt mixture

  poured gives the finished product a surprising improvement

  of mechanical properties, in proportions of between 0.1% and 2% of the total weight of the mixture, the proportion of 0.2% being preferred, since it confers mechanical advantages without

  reduce the workability of the product to be used.

  With equal indentation, the cold traction characteristics are clearly improved, as is apparent from the graph in FIG. 1 where the elongation has been plotted on the abscissa in tenths of the percentage of elongation relative to the initial length and in

  ordered the tensile force in hundreds of Newtons.

  In a manner known per se, the test is carried out at a constant tensile speed of 1 mm / min. According to the graph in fig. 1, the tensile-breaking curves

  were obtained at -10 ° C for a waterproof formulation-

  tee with or without fibers and in two cases of indentation, namely: curves 1 and 2 without fibers, respective indentations IdA 10 and 25, curves 3 and 4 with 0.2% of

  fibers, same respective indentations. The formulas

  with fibers have internal elongation stages

  strong (3, 4) while fiber-free formulations

  give fragile ruptures (1, 2).

  It should also be noted that, with an equal dosage of bitumen, the addition of fibers, even in small quantities, reduces the indentation, that is to say improves the puncture resistance of the finished product. Thus, the graph in FIG. 2, whose coordinate axes have the same units as in FIG. 1, shows that for a very small quantity of fibers of 0.1% the tensile-breaking diagrams are roughly equivalent whereas the indentation is profoundly modified by the presence of fibers: 51 without fibers (curve 5) and only 38 with fibers (curve 6), these

  tests having been conducted at -10 C.

  The addition of short glass fibers therefore makes it possible, by determining the appropriate proportion having regard

  for the use for which the finished product is intended, to adjust the characteristics in cold traction and the characteristics

  Indentation temperatures at positive temperatures. 35 For parking surfaces in particular, it is desirable to have good cold tensile strength and appreciable elongation before breaking, to avoid cold breakdown. It is also desirable, at positive temperatures, to have a good resistance to punching to avoid marking.

  deep tires of parked vehicles.

  Usually, the resistance to the point is improved.

  specifically for positive temperatures by adj-

  tion of a bitumen called "hardening bitumen" in addition to the bitumen 40/50. The fraction of hardening bitumen, grade 105/6, varies depending on the application, from% to 35% of the total weight of the binder. The cost of this hardening bitumen is almost five times the usual 40/50 bitumen. The total cost of the binder is therefore multiplied by 1.4 or 2.4 depending on the application, which must be agreed for parking surfaces that do not puncture. In addition, this hardener bitumen has the disadvantage of stiffening and weakening the cold finished product, the hardness desired at positive temperatures

  having for cons a brittleness when cold.

  Quite usually, when we do not want to use bitumen 105/6 we use bitumen 20/30 stored in a heating tank, which is introduced into the kneader by pumping in addition to the introduction of bitumen 40/50 . We are therefore obliged to have on the installation the possibility of storing in heating tank two different bitumens and to support the

  costs related to this bi-storage. The rheo- disadvantage

  logic is the same as before, namely that obtaining the desired hardness at temperatures

  positive has for counterpart a cold fragility.

  The addition of short glass fibers, in

  appropriate proportions, on the contrary allows

  keep hot a good punching resistance, while preserving a sufficient elasticity when cold and this without using the hardening bitumen: there is an appreciable saving of material, because for a proportion of glass fibers P 103/25 of approximately 0.1% the impact on the finished product is significantly seven times lower than that which would be due to the presence

about 2% of hardener bitumen.

  Furthermore, with regard to the manufacturing economy, it should be noted that the hardener bitumen 105/6 is solid at room temperature. It is delivered by metal drums which must be stored, handled, then cut to extract the product which is then cut to the mass, then weighed

  before being introduced into the mixers.

  With the glass fibers according to the invention, all these operations are eliminated, as are all the costs and drawbacks relating to a possible dual storage of hot bitumens. Indeed, the introduction into the mixture is carried out by directly emptying the number of bags of fibers necessary

in trouble.

  It is also noted that the introduction of the fibers directly into the kneading chute of the kneading machine at the time of loading the locomax transport truck is a simple and convenient means. The dispersion of the fibers in the poured asphalt is very good thanks to the turbulence of the loading operation and it is further improved by mixing

which continues during transport.

  To arrive at establishing the best formulas-

  according to the invention, the Applicant has determined

  the dosages having the desired effects while presenting

  both good handling at implementation.

  The graphs in Figures 3 and 4 summarize the results obtained. On these graphs, we have plotted on the abscissa on a linear scale the percentage of bitumen 40/50 in the total binder which may comprise a hardening bitumen 105/6, said total binder representing 14% or 16% by weight of the final product, as will be better explained below. On the graph of FIG. 3, the Wilson W indentation has been plotted on the ordinate on a logarithmic scale and we have figured

  the two min and max values of the usual range.

  The following curves were obtained: - curve 7, corresponding to 16% of total binder and to 0% of fibers; - curve 8, corresponding to 16% of total binder and to 0.2% of fibers; and, by comparison: - curve 9, corresponding to 15% of total binder and to 0% of fibers; - curve 10, corresponding to 14% of total binder and to 0%

fiber.

  Curves 7 and 8 are the most interesting to compare: we see that curve 8 indicates a reduced indentation and always located in the usual range 20/80, even when there is no longer any hardening bitumen (bitumen content 40/50 equal to 100% of the total binder). It can also be seen that curve 8 indicates very good handling even when there is no longer any hardener (40/50 content equal to 100%). In the latter case the maneuverability is in the vicinity of the maximum of the usual range. These results demonstrate that the formulations (8) with 16% total binder and 0.2% fiber are

  and that hardening bitumen is not necessary to obtain the desired result.

  On the graph of FIG. 4, comprising the same units on the abscissa as in FIG. 3, the workability Xm obtained according to the standardized Bernard-Brunel method is plotted on the ordinate on a logarithmic scale. The values of the usual min-max range have also been shown. On this graph, the curves 11, 12, 13, 14 correspond respectively to the formulations of the curves 7, 8, 9, 10. It is clear from the two diagrams of FIGS. 3 and 4 as the formulation giving curves 8 and 12, in particular to

  % of bitumen 40/50 in the binder, is particular-

advantageous.

  The formulations according to the invention can be successfully applied for single-layer waterproofing coatings of the sand asphalt type, in sites where the annual difference between the maximum and minimum temperature is very large. Furthermore, said formulations are particularly useful for producing the first layer of pure asphalt of bi-layer coatings known per se and intended for

  car parks or structures, it being understood that for these coatings the second layer of gravelled asphalt cannot be reinforced because, during hot brewing, the shocks of the gravel would destroy the glass fibers.

  It is understood that the present invention has been described only for explanatory purposes but in no way

  limitative and that any useful modification25 can be made to it, in particular in the field of technical equivalences, without going beyond its ambit.

Claims (5)

  1. Reinforced mastic asphalt, of the type comprising a binder consisting of bitumen, filler, sand and gravel, obtained by hot mixing between 200 and 250 C approximately, characterized in that its formulation contains from O, 1 to 2 % by weight relative to the binder of short glass fibers, the size of which exhibits softening at the mixing temperatures of the binder, so as to release the strands constituent of said fibers.   2. poured asphalt according to claim 1,   characterized in that the glass fibers present   try a length between 12 and 50 mm, preferably   approximately 25 mm for a diameter of approximately 24 g and   that they are made up of at least 10 elemen- shut up.   3. Mastic asphalt according to one of the claims   1 or 2, characterized in that the fibers of   glass are included in the binder during mixing hot geage.   4. Application of a reinforced mastic asphalt according to   any one of claims 1 to 3 to the realization   tion of a single-layer type waterproofing coating sanded asphalt.   5. Application of a reinforced mastic asphalt according to   any one of claims 1 to 3 to the realization   tion of the first layer of pure asphalt with a coating   two-layer waterproofing or roads.