FI72993B - FOERFARANDE FOER FRAMSTAELLNING AV EN TRYCKHAOLLFAST OCH HOEGSTABIL BELAEGGNINGSMASSA. - Google Patents

Abstract

A method of manufacturing and a use of a compression resistance and high stable surfacing mass for heavy loaded surfaces, especially for strong traffic and heavily loaded street and road sections and mainly comprising a stone material which is bound by an asphalt mass. The surfacing mass is manufactured by heating asphalt at least to the recommended temperature for mixing asphalt with a stone material, and before or after the admixing of asphalt with the stone material a fibre material is added, especially a mineral fibre having an average fibre diameter of between 1 mu m and 5 mu m in an amount of about 0.5-20% of weight in relation to the asphalt weight, and the fibre material is mixed homogenously so as to throughout provide substantially separate fibres in the asphalt phase. When admixing the fibre material before adhesion of the asphalt to the stone material the temperature of the asphalt is preferably increased to 20-40 DEG C above the temperature for mixing the asphalt mass into the stone material, and after a homogenous mixing of asphalt and fibre the asphalt mass is cooled to the said admixing temperature, whereupon the asphalt-fibre mass is mixed homogenously with the stone material.

Description

72993 1 Method for producing a high-pressure compression and a very stable coating mass For the production of high-pressure and high-pressure coating compounds 5

The invention relates to a method for producing a compressive strength and a very stable coating mass for heavily loaded surfaces, which mass consists mainly of rock material bonded with asphalt-10 mass, the asphalt being heated to a temperature at least equal to the temperature recommended for mixing asphalt and rock material with the aggregate at the recommended mixing temperature, the heated asphalt and the heated aggregate are mixed into a homogeneous mixture in a ratio of 15 to 25 parts by weight of 15 aggregates per part by weight of asphalt.

In this application, the term asphalt refers to bitumen or bitumen-containing high molecular weight hydrocarbon.

20 The development of traffic on streets and roads, in terms of both traffic volume and the weight of individual vehicles, has led to high demands on the stability of road surfaces. To a particularly large extent, this applies to hazardous areas, such as traffic lights, road junctions, roundabouts, etc., where paving stones-25 formed by rock material with asphalt as a binder often have insufficient stability.

The lack of stability of the coating mass causes this deformation, in particular due to the fact that the wheels of the vehicle form depressed wheel grooves in the roadway due to the consumption and compaction of the coating mass, which require expensive maintenance. In addition, maintenance work in hazardous areas is very cumbersome to perform and causes traffic disruption to a greater extent than in normal road maintenance.

35 _____ - Τ “· 72993 2 1 Attempts have been made to solve the problem caused by a lack of stability by using so-called body masses, i.e. masses in which the grain size of the rock material is graded so that the load is transferred mainly through the coarse stone granules which rest against each other. In this way, the risk of compression or compaction of the coating-5 mass can be reduced, so that the fewer stones involved in the load transfer have a lower chance of regrouping the stone particles in the rock material.

However, the requirements for the properties of the binder are increasing to a corresponding extent, and in reality the quality of the binder has become the most important factor for the stability of the coating mass. Thus, it is essential that the binder effectively locks the rock particles in their positions and prevents the rock particles from moving or regrouping. The capacity of the binder can be increased by adding a larger amount of binder relative to the amount of rock material. In this case, however, a so-called asphalt runoff problem arises, which means that the warm asphalt drains from the rock particles when mixed with the rock material, which partly counteracts the purpose of the binder addition, and in some cases also causes problems in storage and transport. The stability of the surface mass is not significantly increased, possibly depending on the so-called cold run of the asphalt.

Attempts have been made to solve this problem by adding fine-grained fillerima-25 material, but the result does not appear to be satisfactory. Apparently, the run principle is partially wasted when adding fine-grained fillerima material.

Attempts have been made to solve the problem by adding asbestos fibers. The asbestos fibers 30 have not been shown to produce a sufficient increase in the stability of the body masses at the concentrations that can be technically used. This probably depends on the ability of the asbestos fibers to adhere to each other and form larger entities. In addition, information on the health risks of asbestos fibers has ruled out the use of asbestos in 35 road pavements.

3,799,993 1 Swedish Patent 211,163 also discloses a coating material containing mineral fibers having a diameter of 5 to 15 μm. The proposed coarse mineral fibers have also not proven useful. Probably they tend to be parallel to the rock surfaces in the asphalt rock mass and thus in the plane of the binder film. They then hardly contribute to the stability of the body mass. None of the proposed methods has therefore been put to greater practical use.

10 It has now surprisingly been found that the addition of a mineral fiber material with a small fiber diameter, preferably a fiber material with an average diameter of less than 5 μm and in which the fibers are evenly distributed in the asphalt mass, mainly as individual fibers, greatly reduces binder or asphalt binder or asphalt cold running problems or eliminate them. This gives a binder phase with properties which give the finished coating mass a considerably increased stability compared to previously known coating masses without the viscosity becoming too high at the mixing temperature for rapid and good mixing. The increased stability depends on the increased strength of the binder, which probably depends partly on the increased thickness of the binder film around the stone grains, partly on the fact that the added fibrous material, evenly distributed as individual fibers in the asphalt, also has a reinforcing effect.

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Several different types of materials can be used as fibers, provided that the fibers do not melt in asphalt which, when mixed with the rock material, is at a temperature of about 140-170, preferably at 150-160 ° C, and: provided that the fibers are relatively rigid and retain at least essential stiffness in warm asphalt. Mineral fibers, e.g. rock fibers, i.e. fibers obtained by melting stone as a diabase and then defibering the melt.

35 As mentioned above, the average fiber diameter should be less than 5 μm. When the average fiber diameter is less than 1 pm, the fiber- __- - Έ7 ......

72993 4 1 considerably probably due to the fact that the thin fibers inevitably break largely during mixing. Thus, the average fiber diameter should be 1 to <5 μm. In order to achieve the desired effect, the fibers must be added in an amount of 0.5-20% by weight of asphalt-5, which corresponds to approximately 0.03-1.2% by weight of the finished coating mass.

It is essential that the fibers are not present in the form of tufts or other interlocking assemblies. This can be accomplished by a mixing technique performed with oi-10 kei. In order to facilitate the distribution of the fibers and to avoid the formation of lint and to achieve optimal wetting of the fiber surfaces with asphalt, it may be advantageous to surface treat the fibers with a suitable material. All kinds of non-polar compounds can be used for this purpose, e.g. wetting agents, such as cationic surfactants in the form of tertiary or quaternary ammonium compounds.

It is also preferred that the fibers be as dry as possible when mixed with the asphalt, and in order to achieve an effect similar to said treatment with a wetting agent, it may be advantageous to dry the fibers before mixing them into the asphalt or paving mass to remove most of them. , which are normally absorbed on the surfaces of the fibers.

The addition of fibers can take place by adding them to the stone material before the asphalt is mixed with them, or the fibers can be mixed into the finished asphalt-stone mass. However, a particularly good effect is obtained if the fibers are mixed into the asphalt mass before this is added to the stone material. This facilitates the mixing and homogenization of the fibers, and the mixing of the fibrous and asphalt material can take place in a very gentle manner for the fibers so that the fibers do not break.

The even and unobstructed distribution of the fibers in the asphalt is further promoted if the asphalt is heated during the mixing of the fibers, e.g. 35 20-40 ° C above the temperature of about 150-160 ° C at which the mixing of the asphalt and 5 72993 1 rock material takes place, after which the asphalt-fiber mixture is cooled to this temperature and mixed with the rock material. Raising the temperature lowers the viscosity of the asphalt and thus promotes homogeneous and gentle mixing of the fibrous material, and at this elevated temperature, wetting of the fiber surfaces is further promoted, and the dispersion of the fibers in the asphalt is faster and more efficient.

To evaluate the effect of the addition of fibrous material on the stability of the asphalt pavement, several pulps were prepared according to three different methods and each group had a different amount of added fibrous materials.

Example 1 15

3,100 kg of rock material with a certain defined average grain size distribution was fed to the asphalt mixer. The rock material was heated to 160 ° C and 5.8 kg of mineral fiber material, marked "INORPHIL 057", manufactured by Rockwool AB, was added to the rock material with an average fiber diameter of about 3 μm and a majority of the fibers having a diameter of 1-5 μm.

There is no acceptable direct method for determining fiber length. Rather, the so-called thickening number (n ^) is measured instead, which is calculated by the equation

ή - nQ

ηί = --- 30 ° where Π is the viscosity of the slurry with 1,5 g of dry fiber in 200 ml of ethylene glycol at 20 ° C and the equation has the viscosity of the same ethylene glycol without fibers also measured at 20 ° C with the same 35 devices, namely a Brookfield viscometer with a spindle plumbing or the like. "INORPHIL 057" has a thickening number of 1.0-5.0.

72993 6 1 Example 1

195 kg of asphalt was added to the mixture of rock material and fibrous material.

5

After mixing, the pulp was removed and its stability or post-compaction tendency was measured. This is done according to the following method: 10 An adjusted amount of coating mass was placed in an 8C x 80 mm angled steel frame. A frame with a length of 2000 mm and a width of 40 mm is placed on a concrete floor. The coating compound is insulated from the concrete floor with aluminum foil.

15 After two days at approx. 18 ° C, the altitudes are measured at two points along the center line of the frame with respect to the frame. The distance between the points is 200 mm. The measuring point is formed by a 20 mm round plate which is placed on top of the measuring point during the measurement.

20 A cylindrical roller 100 mm wide and 350 mm in diameter, loaded with 200 kg, is then rotated five times forwards and five times backwards over the mass along the center line. Said dimensions are re-measured and the difference with respect to the original dimension is used as a measure for the post-compaction of the mass. Values are compared to normal mass post-compaction using the following criteria: "normal", 0.8 to 1.2 x normal mass deformation, "certain post-compaction", 1.2 to 1.6 x normal mass deformation, "clear post-compaction" above 1 , 6 x normal mass deformation.

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The experiment in this case showed a clear tendency to post-condense. Examples 2-6 35 Example 1 was repeated with the same type of mineral fibers, but with a different amount of added fibers. The amount of addition and the result are shown in the table below.

Examples 7-9 In these examples, mineral fiber material was added to the heated asphalt before the asphalt-mineral fiber mixture was added and mixed with the rock material. The results are shown in Table 3 below.

Examples 10-12 In these examples, the asphalt was heated to 190 ° C, after which the mineral fiber material was added to the asphalt, the asphalt-mineral fiber mixture was cooled to 160 ° C and mixed with the rock-15 material. The results are shown in the table below.

Example 13 In this example, mineral fibers having an average diameter of 6 to 8 μm were used as a reference, but otherwise the procedure was the same as in Example 1 above.

Example 14 In this example, the same type of mineral fibers as in Examples 1-12 were used, but to determine the effect of fiber length, the fibrous material was ground so that it had a thickening number of 0.2.

30 35 .__ - T ^ - 8 72993 1 Table! ~ j I! ; f

Front; . Footwear! i! 5 brand Fiber type i kg of fiber; % of the asphalt i tion>! i: -i ---- i- 1: INORPHIL 057 0.6 · 0.3% clear 2 "1.2 0.6% certain 3:" 3.9 '2.0% normal Ί0 4 "13, 6 7.0% normal 5 "39.0 | 20.0% normal 6 "58.5 30.0% normal 7 INORPHIL 057 0.6 0.3% certain 8 '" 1.2 0.6% certain 15 9 "3.9 2.0% normal 10 INORPHIL 057 0.6 0.3% certain 11 "1.2 0.6% normal 12" 3.9 2.0% normal 13 coarse 6-8 pm 13.6 7.0% clear 20 14 INORPHIL certain / ground 13 .6 7.0% clear> __

It can be seen from the table above that the minimum amount of fibers added is essential for the stability or post-compaction tendency of the material. Addition of 0.3% by weight of fibrous material of the type shown gives a clear post-compaction tendency according to Examples 1-6 and a certain post-compaction tendency according to Examples 7-12. In contrast, in cases where the addition percentage is approximately 0.5 or higher, normal post-compaction is obtained. This is especially true when the addition occurs in Examples 7-9 or resp. 10-12. The table also shows that the coarse fibers of Example 13 produce a clear post-compaction tendency, and thus that fibers with an average diameter of less than 5 have substantially better properties than the coarser fibers. The table also shows that the ground fibrous material used in Example 14 has a clear tendency to post-compact.

9 72993 1 The accompanying drawing schematically shows an apparatus for producing a coating composition according to the invention. In the tank 1 provided with heat coils 2, the asphalt mass 3 is heated to a normal mixing temperature or, as mentioned above, to a temperature of 20-40 ° C above this mixing temperature. The warm asphalt is pumped by means of a pump 4 in portions into a mixing tank 5 equipped with a mixer 6, to which mineral fibers have been added in portions from the tank 7. The mixture is mixed homogeneously, after which the asphalt pulp is pumped by a pump 8 through a heat exchanger the temperature of the mixture is corrected to the correct mixing temperature of the rock mass. In the case where the mixing of the asphalt and the mineral fibers has taken place at an elevated temperature, the pulp is cooled, and in the case where the mixing has taken place at a normal mixing temperature of, for example, 150-160 ° C and a certain cooling has taken place during the pulp treatment, a certain temperature may be incremental correction may be necessary.

The rock material is heated in a tank 10 provided with a heating member 11 and transferred from it in a batch to a rotating mixer drum-12 12. The pulp from the asphalt and mineral fiber mixing tank 5 is likewise pumped in batches through a heat exchanger 9 to a mixer drum 12 and mixed with rock in both phases. .

As mentioned earlier, the mineral fiber material can be led directly from the mineral fiber tank 7 to the asphalt and mineral fiber mixing drum 12, and in this case the asphalt is of course also pumped directly from the asphalt tank 1 to the mixing drum 12.

It is clear that the above description and the device shown in the drawing are by way of example only, and that many different variations may occur within the scope of the following claims.

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Claims (6)

1 Patent claim A process for producing a pressure-resistant and highly stable coating mass for heavily loaded surfaces and mainly containing a rock material bound by an asphalt mass, wherein asphalt (3) is heated to a temperature at least in accordance with the recommended temperature for mixing the asphalt with the stone material, parallel to this, the stone material is heated to the recommended mixing temperature, the heated asphalt and the heated stone material are mixed to a homogeneous mixture in the proportions of 15-25 parts by weight of the stone material per part by weight of asphalt characterized by adding 0.5-20% by weight during the course of handling. the amount of asphalt of a mineral fiber material having an average fiber diameter of between 1 and <5 µm and of a type which does not dissolve or soften to any significant degree in the hot mass, and which is treated with a wetting agent, e.g. a cationic surfactant prior to the addition of the mineral fiber material to the asphalt. Process according to Claim 1, characterized in that the mineral fiber material is added to the heated asphalt and mixed into a homogeneous mass of fibers dispersed in the asphalt as the asphaltene fiber mass is mixed into the stone material. Process according to claim 2, characterized in that the asphalt is heated to a temperature which is 20-40 ° C above the recommended mixing temperature for asphalt pulp before the addition of the mineral fiber material to the asphalt or before the mixing of the asphalt and mineral fiber material to the stone material. 4. Process according to any one of claims 1,2 or 3, characterized in that the mineral fiber material is completely dried prior to addition to the asphalt material. 5. A process according to any one of claims 2-4, characterized in that the asphalt-fiber mixture is cooled to the recommended admixture temperature prior to the mixing of the asphalt-fiber mass with the rock material.