RU2637701C1 - Radar absorbent asphalt-concrete mixture and roadway covering made from this mixture - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: radar absorbent asphalt-concrete mixture including a bituminous binder, a stabilizing additive, a filler - crushed stone of a various fractional composition, and a fine filler, with using a radar absorbent material, where crushed gabbro-diabase stone and nickel slag and/or copper slag in the form of sand and/or microspheres obtained by a plasma technology, are used as a radar absorbent material at the next component ratio, wt %: said crushed stone 5-70, bituminous binder 5-18, said nickel slag and/or copper slag 8-80, a stabilizing additive 6-16, other filler 2-18. The radar absorbent asphalt-concrete road covering is made multi-layered, where the bottom layer is made from the above mixture, and the upper strengthening layer is made of a mixture containing a binder - an epoxy composition, nickel slag and/or copper slag in the form of sand and/or microspheres made by plasma technology, a pigment and another filler at the following component ratio, wt %: epoxy composition 10-40, said nickel slag and/or copper slag 10-70, pigment 0 or 1-10, another filler 0 or 1-12. The invention is developed in the dependent claim of the formula.

EFFECT: improved operational properties and extended application range.

3 cl, 1 tbl, 1 ex

Description

The invention relates to the field of construction and is intended for covering high-speed routes, airfields, sites for various purposes, requiring high strength coatings, for repairing pavements, marking road surfaces, as well as for coating surfaces that require a decrease in the reflectivity of electromagnetic radiation.

At present, all crushed stone and mastic asphalt mixes used in the Russian Federation must comply with GOST 31015-2002 INTERSTATE MIXTURE STANDARD ASPHALT CONCRETE AND ASPHALT CONCRETE MECHANICALLY MECHANICAL SPECIFICATIONS.

According to the specified GOST, crushed stone and mastic asphalt concrete mix (ЩМАС) is a rationally selected mixture of mineral materials (crushed stone, sand from crushing screenings and mineral powder), road bitumen (with polymer or other additives or without them) and stabilizing additives taken in certain proportions and mixed in the heated state. Crushed stone mastic asphalt concrete (ЩМА) is a compacted crushed stone and mastic asphalt concrete mixture. A stabilizing additive is a substance that exerts a stabilizing effect on SCMAS and ensures its resistance to delamination. As stabilizing additives, for example, Viatop-6 cellulose additive is used.

This composition of the mixtures has insufficient strength characteristics for wear resistance and frost resistance. Repair of coatings made of such asphalt concrete requires the removal of the top coat and subsequent surface leveling before applying a new coat. When icing such coatings, ice can only be removed mechanically. A method of obtaining such a mixture requires a significant expenditure of energy. Patching with such mixtures is difficult.

Various technical solutions are known, with the help of which they try to solve the problem of improving the operational properties of asphalt mixtures.

One of the possible options is the introduction of asphalt concrete mixtures of radar absorbing materials. In this case, it becomes possible to heat such mixtures using the microwave field. This makes it possible to improve some operational characteristics, namely, the process of removing ice from the surface of the coating is simplified; when repairing such a coating, it is not necessary to remove the top layer and leveling, since this can be done by heating the coating to be repaired; when preparing such mixtures, a microwave field can be used, which slightly reduces energy costs.

Various patents are known in the art, for example, US Pat. No. 4,849,020 “Asphalt mixtures and a method for recovering (repairing) asphalt using microwave radiation”.

This patent describes a composition for paving, comprising: a mixture of asphalt and a material that absorbs microwave radiation and dispersed in asphalt to improve the distribution of heating of the mixture under the influence of microwave radiation, moreover, ferrospinel, hexaferrite and their mixture, material can be used from 1% to 25% by weight of the composition.

The radar absorbing materials used in this patent are extremely expensive compared to traditional ones and also lead to chemical pollution of the environment. Such additives usually cannot harden road surfaces.

The PRC application No. 201410583600.5 dated 10.27.2014 “Bituminous mixture for paving that allows the use of microwave radiation to remove ice and snow” is known. The mixture is prepared from: 4-5.5% modified asphalt, 33-65% coarse aggregate, 25-55% fine aggregate, 2-5% mineral powder and 1-5% radar absorbing material. Additionally, the invention describes a method of manufacturing a bitumen mixture for paving. The method includes:

1. Preheating of raw materials

2. Mixing the constituents of the raw materials to obtain a bitumen mixture for paving, allowing the use of microwave radiation to remove ice and snow.

When using a small percentage of the radar absorbing material introduced into the SchMAS, it is not possible to achieve uniform distribution throughout the volume, which leads to a decrease in the heating efficiency and to the possibility of overheating of individual sections of the coating. All this reduces its operational properties. The patent also contains the disadvantages of the above patents.

Thus, all known solutions can only partially improve the operational properties of asphalt mixtures. And some of the above technical solutions are generally unsuitable for use on an industrial scale.

In the work of Vysotsky A.V. (Vysotsky A.V. Effective asphalt concrete on mineral materials from iron-containing technogenic raw materials KMA. Abstract for the degree program of Candidate of Technical Sciences. - Belgorod, 2004. - 23 pp.) It was established that the content of iron oxides in the mineral powder in the amount of 50-80% leads to a significant increase in the corrosion resistance of asphalt concrete and to a decrease in the intensity of bitumen aging due to more active interaction of the surface of the mineral material with its components. But in this work, mineral waste products that contain various impurities, for example, metal, were considered as mineral materials. The presence of metal and other impurities in asphalt mixtures can lead to local overheating when heated in a microwave field, followed by ignition, which is unacceptable.

The authors conducted multiple tests of the compositions of asphalt concrete mixtures for road surfaces and it was found that the replacement of industrially produced crushed stone and mastic asphalt concrete mixtures of mineral powders and some other fillers with high-strength materials in the form of glasses containing iron oxides leads to an unexpected, overly positive effect. In addition to the fact that the asphalt concrete mixture acquires radio-absorbing properties, therefore, it can be heated using a microwave field, but its operational characteristics, such as wear resistance and frost resistance, sharply increase due to more active interaction of the surface of mineral materials with bitumen and other input components under exposure to microwave radiation. Also introduced additives do not contain water, are hydrophobic, have extreme adhesion to bitumen, which leads to increased frost resistance and strength.

As such materials, compositions containing aegirine glass, kuperslag, nickel slag, and some others behaved best. The most durable from the point of view of tribotechnical application proved to be fillers in the form of beads from these glasses, made according to the plasma technology of SPETSKHIMMONTAZh JSC (see link http://www.shm-sbor.ru/activities/production/electrocorundum-microballs/) , as well as various fractions of nickel slag, mainly with particle sizes of 1-5 mm. Such materials have a microhardness of the order of 7-8 GPa, are recommended as high-strength abrasives and, accordingly, are widely used for sandblasting (and ball-blasting) processing of durable surfaces. Raw materials - the charge of nickel slag, as well as kuperslag is industrial waste, the processing and use of such waste is a state task.

The heating of the compositions of asphalt mixtures and pavements with such fillers turned out to be more convenient and safe than heating the materials with water - with uncontrolled humidity, and in particular, since most bitumen is radiolucent and, in dry form, is slightly heated in the microwave field, control the humidity in the field The conditions are just uncomfortable. It is also possible to use the iron oxides contained in the mineral fillers, bringing them to the maximum content of higher oxides (Fe ₂ O ₃ ; Fe ₃ O ₄ ) when heated in the presence of oxygen, which leads to the transformation of the compositions of asphalt concrete mixtures and pavements into magnetically soft, essentially radio absorbing products. Asphalt concrete mixtures with such properties can be heated in a microwave field to a considerable depth, using the entire volume of absorbing material, as well as the underlying (mainly reflective cushion), which makes this heating more intense with little energy.

Repair of pavements made from the proposed mixtures can be carried out not by mechanical means - by cutting, impact, punching, etc., but by softening (heating from the inside) or similarly to the well-known Yutkin method: electromagnetic pulse - in this case, a more powerful microwave radiation package . The softening of the compositions is easily controlled by scanning with non-contact infrared IR thermometers.

Also, the possibility of heating the volume of the proposed asphalt-bitumen mixtures and pavements from these mixtures makes it possible to achieve surface cleaning from ice and snow under extreme weather conditions by heating the coating, followed by separation from the ice surface without chipping and snow with evaporation or sublimation from the surface when the microwave emitter is installed on road equipment. A known method of removing ice and ice from various surfaces is RF patent 2408760, in which heating by directed microwave radiation helps to weaken the molecular bond between the ice and the treated surface. In our case, the radar absorbing coating is heated - asphalt-bitumen mixtures and pavements, which, while retaining heat, prolong the thermal effect of heating on the layer between the ice and the treated surface.

When using beads from radar absorbing materials and crumb rubber as additives in asphalt mixtures with electromagnetic absorbing properties, both self-leveling and crack-resistant compositions were obtained for use in expansion and temperature joints.

The preparation of bitumen compositions with radar absorbing components is technologically simple, because you can save the traditional technology of heating and mixing asphalt mixtures. The difference in the preparation lies in the fact that such materials, when preparing for the batch, are easily and economically dried in the microwave field, while simultaneously heating to the required temperature in the entire volume, additional external heating - for example, with an economical gas burner is not excluded. In this case, it becomes possible to pellet the heated mass in a simple mixer-granulator with the addition of cold or heated bitumen and other additives.

Numerous experiments on such a batch - for example, in granulator-mixers with simultaneous temperature control to avoid overheating, led to unambiguously positive results.

The raw material proposed for use is a charge, for example, nickel slag practically does not contain water, since it is glass. Residual water on the surface of the nickel-slag mixture is easily removed, evaporating, as indicated by the rapidly ending (when heated) steam evolution, even when the mixture is artificially moistened. Especially effective is the removal of water by the microwave method, due to the absorption of microwave radiation and its conversion into heat. The pore sizes between the particles of nickel slag (3 mm - average) make it easy to remove water. Similarly, but slightly worse, the same thing happens when using other mineral radar absorbing fillers, the difference is that such fillers, for example gabbrodiabase, contain a small amount of water (in the pores) that must be removed before the final asphalt product is manufactured to avoid lowering frost resistance .

Uniform heating of the entire volume of the charge can be easily achieved by simply mixing the product (there are many methods of mixing - mixers, rotating drums, etc.) with simultaneous heating in a microwave field.

The mixture, evenly heated, easily rolls in the sense of applying to the entire surface of each particle (nickel slag, etc.) a binder, for example, bitumen, even when it is in a cold state (preferably crushed). Moreover, the particles of the mixture are partially aggregated into granules, which also has a positive effect, since asphalt is usually a multifractional product.

The product mixed in this way is easily modified by additives (rubber crumb, lime powder, nickel slag powder, etc.) simply by continuing the batch. It is not necessary to heat the added additives if they do not constitute a significant part of the mass of the final product. For example, when introducing rubber crumb, there is a danger of loss of properties during heating (depolymerization, etc.), which is ignored by traditional methods. Similarly with other supplements. The proposed method for producing the asphalt mixture is gentle and the final product is sintered into the asphalt already under the pressure of the paver, etc.

The use of microwave installations when laying asphalt allows heating and polymerization, if necessary, directly during roadwork, and not at an asphalt concrete plant. The latter will affect the final product in the most significant way - strength, frost resistance and wear resistance.

Nickel slag powder with a grain size of 1-5 mm is a pH neutral glass, has an acute-angular grain shape and, like all glasses, is excellently coated with bitumen when pelletizing or granulating. It is these properties that make it possible to quickly prepare a high-strength asphalt composition, including with the addition of rubber crumb. The microhardness of such a powder reaches 7-8 GPa, which significantly exceeds traditional fillers.

The disadvantage of all known asphalt compositions is poor adhesion to granite and other stone material when using adhesive additives. This disadvantage is eliminated in the proposed asphalt-bitumen compositions, in particular, by the presence of a material in the form of glass (for example, nickel slag) with high abrasive properties and acute-angled shapes, originally inherent in such materials. The adhesion of nickel slag particles with gabbro-diabase and granite is improved due to its higher strength and high abrasive properties. This was tested on cylindrical samples with a diameter of 60 mm and a height of 200 mm with a composition according to table No. 1, installed vertically for a period of 1 year. The samples were pre-pressed (1 kg / cm ² ); deformation of the samples after a year of storage at a temperature of 26-30 ° C was not observed.

Also, a significant difference from traditional asphalt compositions is the ability of the proposed mixtures not to collapse under the influence of a microwave field of moderate power, but to soften, since the presence of nickel slag leads to the effect of soft softening of the composition with the corresponding possibility of processing it under pressure, for example, leveling with an asphalt paver, including without additional backfilling, or during patching, when it is required to warm up the underlying layer, or the destroyed section of the road surface. When comparing traditional asphalt concrete coatings when heated by an infrared or microwave field, they tried to collapse without preserving the strength properties, and the proposed radar absorbing coating retains its mechanical properties after microwave processing. This was repeatedly tested on samples of the above composition; no noticeable degradation of mechanical properties was found. It is known that secondary asphalt concrete is only partially suitable for secondary use (in retour), the proposed materials are significantly different from the known ones, allowing microwave repair to repeatedly repair and restore road surfaces.

An extremely interesting method of heating such asphalt concrete, in particular, on high-intensity roads in winter, when it is necessary to clear the surface of ice and snow. When passing microwave installations (of known types) along such a road surface, heat accumulates in it to a depth of 30-100 mm and then slowly released (due to low thermal conductivity) and allowing melt ice and snow.

The closest set of essential features to the proposed technical solution is the Patent of the People's Republic of China No. 101736671 “Radar Absorbing Asphalt Concrete Composition for Paving”.

The disadvantages of the technical solution described in the patent are that it is proposed to use magnetic sand or sand from carborundum (silicon carbide) as radar absorbing fillers. These are extremely expensive materials, and such compositions are prone to local overheating in the microwave field, such as fine-grained powders, and the required particle size distribution is not produced, which prevents the creation of SchMAS that meet the requirements of GOST. Also such a composition of the asphalt concrete composition has insufficient wear resistance and frost resistance.

The technical problem solved by this invention is the creation of a new generation of radar absorbing asphalt concrete mix with improved performance properties and a wide range of applications.

The technical result is to improve operational properties and expand the range of applications.

The technical result is achieved due to the fact that in a radar absorbing asphalt mixture, including crushed stone of various fractional composition, bituminous binder, stabilizing additives and radar absorbing material, it is proposed to use gabbro-diabase crushed stone and foundry slags, mainly amorphous glass of various fractional composition, as the main radar absorbing materials. and forms, including in the form of microspheres made by plasma technology.

Additional differences of the proposed mixture are:

1. The components of the mixture are contained in the following ratio:

Gabbro-diabase gravel of various fractional composition 5-70%

Bituminous binder 5-18%

Foundry slags 8-80%

Stabilizing additive 6-16%

Other excipients 2-18%

2. Nickel slag and / or kuperslag were used as foundry slag.

3. Nickel slag and / or cooper slag is also used in the form of microspheres made by plasma technology.

As a prototype for the proposed pavement selected technical solution according to US patent 8,753,035. It describes “Asphalt Concrete Pavement Containing Radar Absorbing Material, and the Maintenance and Repair Process of Such Pavement”.

Asphalt coating includes:

1. Coarse-grained material consisting of small stones with a grain size of 10-15 mm, crushed stone with a grain size of 5-10 mm and small stones of 0.1-5 mm

2. Sand filler

3. Mineral powder containing radar absorbing material, comprising from 10% to 100% by weight of the mineral powder.

Known asphalt concrete pavement contains a top layer, a middle layer and a lower layer, the amount of radar absorbing material in the upper, middle and lower layer being different. The dependent claim states that the radar absorbing material is selected from ferrite, fly ash, hollow glass, nanometric hollow glass, hollow porous carbon fiber, and a combination thereof.

The radar absorbing materials used in this patent are expensive, lead to chemical pollution of the environment, and also do not increase the wear resistance and frost resistance of the asphalt concrete pavement. The additives used in this patent have a high reflection coefficient of microwave radiation, which leads to local heating of the coating, as well as to heating only the surface layer of the road surface. Such additives cannot serve in asphalt for more than 2 months due to the high solubility of these glasses in bitumen.

Regular glass is a highly alkaline product - unlike special glasses, for example nickel slag, kuperslag (pH - neutral and insoluble in bitumen, as well as incomparably harder and stronger). The cited patents used materials - low hardness glass (especially foam glass), which also raises doubts about the practical suitability of the mixtures for roads.

The technical problem solved by the invention is the creation of such a radar absorbing asphalt pavement, which would have improved cost, operational and repair characteristics, as well as would have a wide range of applications.

The technical result is the creation of a radar absorbing asphalt mixture with improved technical characteristics and a wide range of applications.

The technical result is achieved due to the fact that the radar absorbing asphalt concrete pavement made of multilayer, in which the lower layer includes crushed stone of various fractional composition, bitumen binder, stabilizing additives and radar absorbing material, is proposed to be made of two layers. Moreover, as the main radar absorbing materials for the lower layer, gabbro-diabase rubble and foundry slags, mainly amorphous glass of various fractional composition and shape, including in the form of microspheres made by plasma technology, are used. While the upper reinforcing layer is proposed to be performed on the basis of epoxy components with the addition of foundry slags of various fractional composition and shape, mainly amorphous glasses of various fractional composition and shape, including in the form of microspheres made by plasma technology.

Additional features of the proposed pavement are:

1. The components of the lower layer are contained in the following ratio:

Gabbro-diabase gravel of various fractional composition 5-70%

Bituminous binder 5-18%

Foundry slags 8-80%

Stabilizing additive 6-16%

Other excipients 2-18%

2. Nickel slag and / or kuperslag were used as foundry slag.

3. Nickel slag and / or cooper slag in the upper reinforcing layer can be used mainly in the form of microspheres made by plasma technology.

4. The upper reinforcing coating layer may also contain coloring pigment and / or crumb rubber.

5. The components of the top coating layer are contained in the following ratio:

Epoxy composition 10-40%

Foundry slags 10-70%

Coloring fillers 1-10%

Other excipients 1-12%

6. The reinforcing layer is applied using microwave technology (in the presence of a microwave field).

In the preparation (preparation) of the asphalt-concrete mixture, such a mixture is heated including in the microwave field (in this case, residual moisture (water) is effectively removed from the powder, granules, gravel), which leads to an improvement in the quality of the product. Effective heating, complemented by mixing - the effective distribution of a bituminous binder over the surface of the particles and the homogenization of the final product. In the process of transportation, repair, such a mixture is easily heated in a microwave field, which also allows the use of even cooled (followed by heating in the indicated way) crushed stone-mastic asphalt concrete mixtures.

Additives introduced during mixing do not change their physicochemical properties, which allows, for example, rubber crumb or coloring pigments to be introduced into asphalt mixes.

Example 1

One example of the composition of the radar absorbing asphalt concrete mixes of alkali metal oxide is given in table 1.

For a sample of alkali-alkali metal alloy - an asphalt mix according to the recipe with a coating thickness of 1.8 mm with nickel slag microspheres on an epoxy binder, measurements were made on the waveguide line with a cross section of 72 × 34 mm (WR-284) S12. An energy absorption of 0.6 dB / cm was obtained at a frequency of 2750 MHz (5 cm - 2-fold). In a real section, for an asphalt thickness of 10 cm, heating was carried out over the entire thickness (depth) of the layer. That is, all asphalt was heated up to 10 cm evenly, without a temperature gradient (the temperature difference between the upper and lower layers did not exceed 8 ° C) at a heating temperature of 80 ° C.

When using the proposed mixture, a reinforcing layer on top of such asphalt concrete is carried out by subsequent application of an epoxy composition with a radio-absorbing filler in the composition of nickel slag 100-1000 microns and nickel slag balls 100-800 microns in the amount of not less than 60% of the composition, followed by short-term heating in a microwave field to a temperature of no more than 80 ° C.

This method of applying a reinforcing layer is based on the microwave curing effect of the epoxy resin with a multiple increase in its strength and curing rate, which leads to the appearance of an ultra-strong coating in the presence of particularly strong fillers of microspheres and nickel slag. The greatest effect is achieved when applying such a coating on hot asphalt of the above composition at a temperature of 50-60 ° C.

When determining the abrasion by studded tires of cylindrical asphalt concrete samples on a CRT-PRALL device according to method A ODM218.2.019-2011, the abrasion value Abr - 0 ml was obtained on two samples (the absence of similar analogues).

For road marking, a preferably titanium pigment is introduced into the above epoxy composition, and before heating with a microwave field, a reflective material, for example microspheres, is sprinkled.

The strengthening layer when using the proposed coating after heating in a microwave field and before curing is sprinkled with nickel slag powder, nickel slag microspheres (desired fraction) or a mixture of nickel slag powder with crumb rubber to create the required surface roughness.

A repair composition of such a mixture for patching an asphalt concrete pavement is prepared with the addition of nickel slag microspheres 5-60% of the total mass to obtain a self-leveling frost-resistant coating.

A repair composition for patching an asphalt concrete pavement can also be prepared with the addition of microspheres insoluble in a bitumen binder, or other microspheres coated with an insoluble bitumen binder.

The repair composition for patching the asphalt concrete coating is prepared with the addition of beads, thermoplastics powders, followed by short-term heating of the microwave to a temperature of not more than 180 ° C.

Due to the fact that the introduced radar absorbing additives are evenly distributed throughout the volume of the mixture, the whole mixture acquires radar absorbing properties and can be used to cover structures whose reflectance of electromagnetic radiation must be reduced. For example, nuclear power plants, military facilities, etc. Such a mixture can cover, for example, the roofs of such structures.

The proposed radar absorbing asphalt mixes have the following advantages over currently used and described in known analogues:

- significantly improves the operational properties of road surfaces made from such mixtures, such as wear resistance and frost resistance;

- decreases the ability of the coating to crack;

- improves maintainability of the coating;

- the range of application is expanding;

- reduced energy consumption during production;

- there is an opportunity to combat icing.

- the applied components of the proposed pavements are quite cheap and well-known.

Claims (5)

1. Radar absorbing asphalt concrete mixture, including a bituminous binder, stabilizing additive, filler - gravel of various fractional composition and fine filler using a radar absorbing material, characterized in that gabbro-diabase gravel and nickel slag and / or cooper slag in the form of sand are used as radar absorbing material and / or beads obtained by plasma technology, in the following ratio of components, mass. %: specified crushed stone 5-70 bituminous astringent 5-18 specified nickel slag and / or kuperslag 8-80 stabilizing additive 6-16 another filler 2-18 2. Radar absorbing asphalt concrete pavement made multilayer, and the lower layer is made of a mixture according to claim 1, and the upper reinforcing layer is made of a mixture containing an adhesive - epoxy composition, nickel slag and / or kuperslag in the form of sand and / or beads made according to plasma technology, pigment and other filler in the following ratio of components, mass. %: epoxy composition 10-40 specified nickel slag and / or kuperslag 10-70 pigment 0 or 1-10 another filler 0 or 1-12 3. Radar absorbing asphalt concrete pavement according to claim 2, characterized in that the reinforcing layer is applied in the presence of a microwave field.