RU2759141C1 - Method for producing cold asphalt concrete - Google Patents

Abstract

FIELD: road building materials.SUBSTANCE: invention relates to the field of road building materials, in particular to a method for manufacturing a cold asphalt concrete mixture from an old asphalt concrete road surface for use in the repair of an asphalt concrete road surface. A method for manufacturing cold asphalt concrete mixture, including mixing milled asphalt crumb and 1-4 wt.% of a binder based on bitumen and divinyl-styrene thermoplastic elastomer, diluted in a mixture of diesel fuel and an aromatic solvent, characterized in that a modifier obtained by interaction of drying vegetable oils: linseed or tung or camelina, sulfur and metal salts of variable valence - desiccant NF-1.EFFECT: simplification of the manufacture of cold asphalt concrete mixture and an increase in its physical and mechanical properties.3 cl, 4 tbl

Description

The claimed invention relates to the production of road building materials and can be used for local repair of the roadway and the device of lightly loaded roads of regional importance, pedestrian and bicycle paths, namely for the production of cold asphalt concrete mixtures without heating the fillers and binder to high temperatures typical of the traditional method production of "hot" asphalt.

The problem of recycling asphalt pavements has been known for a long time.

A known method of manufacturing cold asphalt from asphalt scrap (USSR author's certificate No. 83827, publication date: 06/05/1975) by mixing crushed asphalt scrap in paddle mixers with liquid bitumen or bitumen-like materials or emulsions.

Also known is a composition for the preparation of cold asphalt concrete (patent for invention of the Russian Federation No. 2535325, publication date: 03.09.2013), containing bitumen, oil sludge, screening of crushing granite and limestone mineral powder.

The main disadvantages include the small size of mineral particles and, as a result, the ability to repair only cracks and minor damage to the road surface.

Also known is a reclaimed asphalt concrete mixture and a method for its preparation (patent for invention of the Russian Federation No. 2164900, publication date: 06/28/1999). The regenerated mixture contains in% mass: crushed asphalt concrete 30-70, crushed stone and sand 28-68, mineral powder 6-14, bitumen 2-7. For regeneration, mineral materials (crushed stone and sand) are heated to a temperature of 210-330 ° C, bitumen to an operating temperature. Crushed asphalt concrete and mineral powder are used at ambient temperatures. The components are mixed and kept under thermostated conditions and finally mixed again.

Significant disadvantages are the high costs of heating and two-stage mixing.

Closest to the proposed invention, taken as a prototype, is a method for the production of polymer cold asphalt from milled old asphalt concrete (patent for invention of the Russian Federation No. 2702434, publication date: 08.10.2019). The method is characterized in that the asphalt concrete removed from the upper part of the road surface is heated to 40-60 ° C and mixed with 0.5-5% of a binder, including diesel fuel, a modifier, while the modifier contains divinyl styrene thermoplastic, heat transfer oil AMT-300 , polyethylenepolyamine, a mixture of liquid acids of vegetable oils with the following ratio of components, wt%: divinylstyrene thermoplastic elastomer 2-30, heat carrier oil AMT-300 42-91, polyethylenepolyamine 3-12, a mixture of fatty acids of vegetable oils 4-16, and the content of the modifier in astringent is 5-35%.

In the selected prototype, it is proposed to heat the milled asphalt concrete to a temperature of 40-60 ° C, which in itself is energy-intensive (about half of the amount of heat required to heat the components of the new asphalt concrete, taking into account the low thermal conductivity of the old asphalt concrete crumb and the need for continuous stirring during heating to avoid sticking milled old asphalt concrete).

The relatively low values of the ultimate strength in compression, 0.4-0.5 MPa, can be explained by the plasticizing effect of the AMT-300 coolant, which does not have functional groups responsible for the occurrence of interaction between granules of old asphalt. The high boiling point of ATM-300 does not allow it to quickly evaporate after laying and tamping, thereby reducing the strength of the composition in compression at 20 ° C.

The same circumstance explains the high value of miscibility (1-4 strokes).

In addition, the product is highly toxic and carcinogenic, especially at elevated temperatures of 40-60 ° C.

All of the above are significant and basic disadvantages of the prototype and the objective reasons for their occurrence.

The technical problem to be solved by the claimed invention lies in the development of a method for producing cold asphalt concrete mixture for patching the road surface, which does not require complex and road equipment.

The task of the claimed technical solution is to eliminate the disadvantages of analogues and prototype.

The technical result is to simplify the manufacture of cold asphalt concrete mixture and increase its physical and mechanical properties.

The technical result is achieved due to the fact that the method of manufacturing cold asphalt concrete mixture is characterized by the fact that 1-4% of a binder based on bitumen and divinyl-styrene thermoplastic elastomer, diluted in a mixture of diesel fuel and an aromatic solvent by mixing the components, is introduced into the milled asphalt crumb.

The novelty is that a modifier is introduced into the binder, obtained by the interaction of oxidized vegetable oils, sulfur and compounds of metals of variable valence.

In this case, the mixing is carried out mechanically in the ratio: milled crumb of the old road surface 96-98% by weight, a solution of bitumen with divinyl-styrene thermoplastic elastomer in a mixture of diesel fuel and aromatic solvent 1-2% by weight. and a modifier based on oxidized vegetable oil, sulfur and metal compounds of variable valence 1-2% of the mass.

In this case, the method of manufacturing cold asphalt concrete mixture contains in the amount of 1-3 mass. % relative to the mass of bituminous binder derivative of tall oil.

In this case, the method of manufacturing cold asphalt concrete mixture contains a modifier obtained on the basis of drying vegetable oils of linseed, tung and camelina.

The technology for the manufacture of cold asphalt concrete mixture is shown in example No. 1.

Example No. 1.

Milled asphalt chips with a coarse fraction of not more than 25 mm are mixed in a horizontal mixer with 0.3% of the mass. (30% bitumen solution in diesel fuel containing 3.6% divinyl-styrene thermoplastic elastomer) and 0.3% modifier (the product of the interaction of oxidized vegetable oil with 1% sulfur and 1% metal salts of variable valence - desiccant NF 1). The resulting processed crumb is kept for 24 hours to undergo the modification process. For testing, cylindrical samples with a diameter of 71.4 mm and a height of 71.4 mm are pressed from cold asphalt. Determine the compressive strength of cold asphalt. For a given specimen, compression σ = 1.2 MPa.

Table 1 shows the composition of the binder in% of the mass. from the amount of cold asphalt concrete.

Table No. 1. Compositions of asphalt concrete

The amount of modifier per 100 kg of cold asphalt concrete Example No. 1 2 3 4 5 6 7 eight nine 0.6 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Comparison of physical and mechanical properties (ultimate strength in compression, 20 ° C MPa) is carried out on samples of asphalt concrete mixtures with a modifier at various concentrations of the modifier in Table 2.

Examples No. 2-9.

Table 2. Ultimate compressive strength, 20 ° C, MPa of asphalt concrete samples depending on the concentration of the modifier

Example number 1 2 3 4 5 6 7 eight nine Tensile strength
at compression 20 ° С, MPa 1,2
1.5 1.85 2.10 2.12 1.95 1.70 1.60 1.42

According to the technology given in example No. 1, samples of cold asphalt concrete mixture with different concentrations of the modifier ˗ of the product of the interaction of oxidizing vegetable oils with sulfur and metal compounds of variable valence are made.

For testing, cylindrical specimens with a diameter of 74.4 mm and a height of 71 mm are pressed from a cold asphalt concrete mixture. Determine the compressive strength of cold asphalt concrete.

The results of tests for compressive strength are shown in Table 2. Analysis of the data obtained shows that the dependence of the compressive strength of asphalt concrete on the modifier content is extreme and has maximum values at a content of 1-4%. The extreme nature of the dependence can be explained by the optimal number of new physical and chemical bonds arising from the interaction of the surface of the milled asphalt concrete crumb with the modifier.

A slight decrease in the compressive strength of the samples with a modifier content above 4% is associated with the platinizing effect of the modifier and the formation of less durable diffuse layers between the milled asphalt concrete particles.

The results of testing samples of asphalt concrete from cold mixes show that samples with a modifier content of 1.0% of the mass. up to 4.0% of the mass. (examples No. 2 - 8) have an increased compressive strength.

According to GOST 9128-2009, this indicator for cold asphalt should be at least 1.5 MPa.

Further studies have shown that the introduction of an additional 1-3% of the mass into the modifier. derivative of tall oil, gives an increase in the compressive strength of samples made from cold asphalt concrete mixtures. The test results are shown in table No. 3.

Table 3. Strength of samples at compression 20 ° С, MPa depending on the concentration of the tallow oil derivative

Sample no. The content of the modifier in the mixture% wt. The content of the derivative tall oil in the modifier% wt. Compressive strength 20 ° C, MPa 3 1.5 0 1.85 ten 1.5 1 1.9 eleven 1.5 2 2.0 12 1.5 3 2.0

An increase in strength characteristics is associated with an increase in the viscosity of the modifier and an improvement in the adhesion interaction between the particles of the milled old asphalt pavement.

The influence of the nature of oxidized vegetable oils on the compressive strength of cold asphalt concrete samples with a modifier based on various vegetable oils has been investigated.

The test results of the samples are shown in Table 4.

Table No. 4. Influence of the nature of oxidized vegetable oils on the compressive strength of cold asphalt concrete samples

Example No. Vegetable oil type Content in the modifier, wt% Dosage of the modifier in cold asphalt concrete. Compressive strength 20 ° C, MPa 4 Sunflower 50 2 2.1 13 Linseed 50 2 2.4 fourteen Tungovoye 50 2 2.2 15 Ryzhikovoe 50 2 2.2

Higher values of the compressive strength of the tested samples are associated with the fact that linseed, tung and camelina oils are drying out, in contrast to sunflower, therefore, cold asphalt concrete, due to the deeper modification of drying oils, has higher rates.

All of the above examples show the positive effect of using the modifier in cold asphalt mixes.

The shelf life of these mixtures in unheated, protected from direct sunlight, exceeds 12 months.

In the submitted materials of the application, the modifier used for the treatment of asphalt concrete crumb is a product of the interaction of oxidized vegetable oils, sulfur and compounds of metals of variable valence.

Oxidized vegetable oils have additional carboxyl groups and additional double bonds that occur when oils are oxidized at high temperatures.

In the presence of compounds of metals of variable valence and sulfur, additional sulfide and disulfide and epoxy groups appear, which provide higher adhesion characteristics of old asphalt concrete particles and, as a consequence, increased compressive strength of samples 1.5-2.12 MPa.

Decrease in ultimate strength in compression using a modifier over 4.0% of the mass. explainable by the occurrence of a platinizing action, which neutralizes the emergence of new physical and chemical bonds.

When repairing the roadway, cold asphalt is laid in a pit with leveled edges and cleaned of dust, snow and excess moisture. A vibrating plate or rammer is used to compact the material.

Claims (3)

1. A method of manufacturing a cold asphalt concrete mixture, including mixing milled asphalt crumb and 1-4 wt.% Of a binder based on bitumen and divinyl-styrene thermoplastic elastomer, diluted in a mixture of diesel fuel and an aromatic solvent, characterized in that a modifier obtained by interaction of drying vegetable oils: linseed or tung or camelina, sulfur and salts of metals of variable valence - desiccant NF-1. 2. A method of manufacturing cold asphalt concrete mixture according to claim 1, characterized in that the mixing is carried out mechanically with the following ratio of components, wt.%: Milled crumb of the old road surface 96-98, a solution of bitumen with divinyl-styrene thermoplastic elastomer, diluted in a mixture of diesel fuel and aromatic solvent 1-2, a modifier based on the specified drying vegetable oil, sulfur and metal salts of variable valence - desiccant NF-1 1-2. 3. A method of manufacturing cold asphalt concrete mixture according to claim 1, characterized in that the binder contains in the amount of 1-3 wt.% Relative to the weight of the bituminous binder, a derivative of tall oil.