FI78722C - FOERFARANDE FOER REGENERERING AV ASFALTBETONG MED ANVAEND MOTOROLJA. - Google Patents

Description

1 78722

Method for regenerating asphalt concrete with used engine oil

The invention relates to road construction materials 5 and more particularly to a method for regenerating asphalt concrete, which method has a wide range of applications in the construction and, in particular, repair of asphalt-concrete pavements for roads.

In practice, asphalt concrete pavements 10 tend to be damaged, resulting in soft runoff, fractures and potholes.

Regeneration methods such as "repair", "resurfacing" and "remixing" are used to repair pavements of asphalt concrete roads, which methods allow the pavement to be restored to smoothness and integrity.

"Repair" is the most effective and simplest method. It is used if abundant leveling of the road surface is not necessary (for example, there are no tracks deeper than 2 cm). 20 Experience has shown that this method does not always work well for the effective compaction of a thin layer of obsolete asphalt concrete and, moreover, the fragility of obsolete bitumen cannot be eliminated.

The "resurfacing" and "remixing" methods add a new bituminous concrete mix to the old one; in the first case it is added to the leveled pavement of the old asphalt concrete mix and in the second case it is mixed with the old asphalt concrete mix. In the "recoating" method, the properties of the old asphalt concrete-30 mixture are not restored, although when applying a new surface layer it is possible to extend the service life of the regenerated pavement compared to the pavement repaired by the "repair" method.

In the "remixing" method, regeneration of as-35 asphalt concrete can be performed, namely sorting of aggregate, and in part the properties of the old bitumen are improved. However, in order to improve the properties of the old bitumen, it is advantageous to add a large amount of new mixture (at least 40-50% by weight of the old asphalt concrete mixture).

2,78722 When treating asphalt concrete to regenerate it, the treatment stations aim to add various reducing agents to the old mixture, thus obtaining high-quality regenerated asphalt concrete. However, said method is more laborious and expensive than in situ asphalt concrete regeneration methods, i.e. on roads.

Methods for in situ regeneration of asphalt concrete pavements are known in the art, which methods are performed by adding a reducing agent to both the hot and cold mixes; and this makes it possible to obtain a high quality coating using a smaller amount of new mixture.

The main purpose of reducing agents is to reduce the brittleness of old bitumen and thus reduce the brittleness of asphalt concrete at low temperatures. In addition, the reducing agents 15 regularly both reduce the viscosity of the old bitumen and lower the strength of the asphalt concrete at positive temperatures, which can lead to a decrease in the shear strength of the latter. In addition, some reducing agents can impair the corrosion resistance (weather resistance) of asphalt concrete, i.e., its resistance to water and frost.

Several hydrocarbon compositions have been used as reducing agents, mainly in the form of emulsions, for example "reclamate", "cyclogen" and others. The disadvantage of most reducing agents is their toxicity and high cost.

Methods for repairing asphalt concrete pavements are known in the art which provide an improvement in asphalt concrete when using oil emulsions. The known process uses a rock oil emulsion as a reducing agent which is added to crushed asphalt concrete (U.S. Pat. No. 3,162,101).

However, the water content of the emulsion limits the use of said reducing agent to cold mixtures which are applied to second-class roads or to the subfloors of pavements.

A method for regenerating asphalt concrete is known in the art by grinding asphalt concrete waste, heating it and mixing it with a reducing agent, namely a liquid black binder, which is a waste oil product having a density of less than 1% by weight of an binder content of 15 to 20% by weight. (cf. SU Inventor's Certificate No. 894,034). The said petroleum product waste is obtained from the refinery's wastewater treatment plants. This method is characterized by a large variation in the viscosity of waste oil products (5 x 10 to 100 x 10 m / s), and this causes different strength and flow properties in regenerated asphalt concrete and as a result limits the service life of individual sections of pavements, resulting in high brittleness and poor corrosion resistance. . In addition, the strength of the regenerated asphalt concrete decreases at a temperature of 10 to 50 ° C, i.e. its heat resistance deteriorates compared to the original pavement.

The object of the invention is to develop a method for regenerating asphalt concrete using a new reducing agent, which makes it possible to reduce the brittleness of asphalt concrete and make it corrosion-resistant and heat-resistant.

The above object is achieved by using a method for regenerating asphalt concrete by grinding it and adding a reducing agent to the asphalt concrete mixture, using the engine oil used according to the invention as a reducing agent in an amount of 0.1 to 1% by weight of the asphalt concrete.

It is preferable to use the above-mentioned spent engine oil having a kinematic viscosity of 25 x 10-6 to 70 x 10 6 m 2 / s at a temperature of 50 ° C. Said range is chosen because the low viscosity corresponds to the increased concentration of the volatile component and the light residues in the waste oil pose a risk of sudden ignition, while the high viscosity makes it difficult to add it to the asphalt concrete mix.

Preferably, in order to distribute the reducing agent more evenly in the asphalt concrete mixture, the asphalt concrete mixture is heated to a temperature of 50 to 130 ° C before and / or after grinding and the addition of the reducing agent is carried out with stirring of the asphalt concrete mixture.

The process for regenerating asphalt concrete according to the present invention is carried out as follows: the asphalt concrete is ground and a reducing agent, motor waste oil, is added to obtain a mixture containing 0.1 to 14,78722% by weight of the asphalt concrete. Waste oil is a group of petroleum products formed when engine oil is used in an engine and are mainly mixtures of distillates and residual components with the organometallic complex 5.

When engine oil performs its function in an engine, hydrocarbons are subject to oxidation, oxidative polymerization, condensation, and decomposition. Products from worn parts penetrate oil and fuel and the or-10 ganometallic complex is modified.

The group of used engine oils includes waste oils from automobiles, diesel and aircraft engines used in transmissions and hydraulic systems. The diversity 15 of the group of engine oils used is the reason for the wide variation in their properties. The physico-mechanical properties of the engine oils used are as follows: kinematic viscosity, m2 / s at 50 ° C 25 x 10-6 - 70 x 10-6

20 flash points in an open cup 100-180 ° C

mechanical impurities, not more than 2% by weight of water, not more than 4% by weight of fuel (petrol or diesel), not more than 6% by weight of 25 hydrocarbons, in waste oils: paraffin naphthenes 50 to 70% by weight aromatics 25 to 40% by weight resins 3-8% by weight of asphaltenes, carbenes, carboids 2-6% by weight In addition to the above-mentioned hydrocarbon components, the waste engine oil contains an organometallic complex; the carbon limustaa; lacquer and coke components, etc.

The organometallic complex of waste oil consists of metal salts, mainly alkaline earth metal salts, with long aliphatic hydrocarbon chains containing compounds of polar groups. Alkaline earth metal salts consist mainly of the calcium and barium salts of sulfonic acid.

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Unlike engine oil, the engine liner used contains micelles with a core insoluble in Sljy (an internal oxidation and condensation product) and a shell of the organometallic complex.

The amount of reducing agent to be added as a reducing agent to the asphalt concrete mixture depends on the porosity of the regenerated asphalt concrete mixture and the degree of aging of the bitumen, and is 0.1 to 1% by weight of the asphalt concrete.

The minimum amount of reducing agent is added to asphalt concrete-10 with a low porosity (2-3%) and a short pavement life (4-7 years) and the largest amount is added to asphalt concrete with a high porosity (greater than 5%) and a long pavement life ( more than 10 years).

15 Said waste oil as a reducing agent not only reduces the brittleness of the asphalt concrete at negative temperatures, but also provides a sufficiently good corrosion and heat resistance.

This effect of the waste oil is related to the presence of the above-mentioned compounds formed by the action of oxidation in the presence of an organometallic complex. In addition, these compounds adsorbed on the bitumen films allow the reduction of friction between the aggregates of the old asphalt concrete mix as they are compacted, resulting in a denser-25 mix. The presence of a certain amount of fuel (gasoline or diesel fuel) in the used engine compartment increases the penetration capacity of the reducing agent into the aggregate components of the old asphalt concrete layer.

The process of the present invention is suitable for both "cold" and "hot" regeneration. It is advantageous if, before and / or after grinding, the asphalt concrete is preheated to a temperature of 50 to 130 ° C in order to obtain regenerated asphalt concrete with an increased density, which prolongs its service life. The upper limit is determined by the strong evaporation of the waste-35 oil when added to the mixture.

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The efficiency of regeneration of asphalt concrete is improved if the reducing agent is added to the mixture with stirring, thereby increasing its heterogeneity and improving the physico-mechanical properties of the regenerated asphalt concrete.

Using the hot method of repairing asphalt concrete pavements in situ according to the present invention, the procedure is performed in the following step: the pavement is preheated to a temperature of 50 to 130 ° C; then it is crushed to a depth of 3 to 5 cm by removal with 10 or round nails; the waste oil is added to the ground mixture; and the resulting mixture is leveled and concentrated.

If the addition of a new asphalt concrete mix is required to ensure an even repaired road surface or to improve the size distribution of the mix, methods known in the art are used.

The invention is further described by means of examples which illustrate certain embodiments thereof.

The corrosion resistance of asphalt concrete is determined in the examples by means of a water resistance factor and a long-term water resistance factor.

The water resistance factor of asphalt concrete is calculated from the formula: K _ w R20 25 where Rw and R2q are the final strength values of the asphalt concrete when compressed at 20 ° C after impregnation with vacuum water and dry sample values, respectively.

Long-term water resistance coefficient of asphalt concrete

30 is calculated from the formula: R T

K = wL WL "R20 where RwL is similar to Rw when keeping water-saturated samples in water for 15 days.

Example 1 35 An asphalt concrete pavement containing 40% by weight of 5/15 mm crushed stone and used for 16 years was heated and round nailed. A reducing agent was added to the resulting mixture; in the first case it was waste oil 7 78722 and in the second case it was liquid petroleum products obtained from the refinery's waste water treatment plants (cf. SU inventor certificate No 894 034). Samples were taken from the mixtures prepared as described above.

Table I shows the properties of asphalt concrete according to the present invention and SU inventor certificate No. 894,034.

Table I

! --- '10 Properties of Asphalt Concrete_ Starting Material- In the present SU-inventor-asphalt invention, a certificate of

Reduced concrete No. 894034 No. 15 ________ reductant

Amount of reducing agent,% by weight ___ 0.1 0.5__1.0 1.0 1 2 3 4 5 6 7 final compressive strength, MPa at ° C 1 50 2.7 + 0.2 2.4 + 0, 1 1.2 + 0.10.8 + 0.1 0.5 + 0.1 2 20 8.5 + 0.4 5.6 +0.2 4.1 + 0.2 3.7 + 0, 2 3.2 + 0.2 25 3 0 13.4 + 0.5 10.2 + 0.4 7.0 + 0.36.6 + 0.2 6.3 + 0.2 (water resistance factor 0 .68 0.75 1.00 0.86 0.78 M ·· I '' I - * —11 -. II.! 1 I. II »....... II ..... -. · l.

The values shown show that the brittleness of asphalt tibetone made in accordance with the present invention is not only reduced, but also has better corrosion and heat resistance compared to the method of U.S. Inventor Certificate No. 894,934.

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Example 2

Asphalt concrete samples were prepared from an asphalt-concrete mixture taken from the surface of the asphalt concrete pavement after it was heated and removed.

5 The asphalt concrete pavement had been in use for 7 years. The composition of the asphalt concrete, determined after bitumen extraction, was in% by weight: crushed stone 5/15 38 sand 52 10 mineral powder 10 bitumen 6.3 (in addition to 100% mineral mixture)

Various oils from the group of used engine oils, 15 which included a mixture of engine and propeller aircraft, diesel aircraft and aircraft oils, were used as a reducing agent to prepare samples.

the kinematic viscosities of the oils were 25 x 10 43 x 10 ® and 70 x 10 ~ ^ m ^ / s, respectively. The samples were prepared by heating the asphalt concrete mixture to a temperature of 110 + 10 ° C, adding a reducing agent with stirring and then compacting. The reducing agent content was 0.3, 0.6 and 0.9% by weight of the asphalt concrete.

The physical properties of the waste oils used to prepare the samples are shown in Table II.

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Table II oil type aircraft engine and oil mixture 5 tractor no Feature 34 5 1 density, ~ 10 g / cm 0.85 0.86 0.86 2 kinematic viscosity at 50 ° C, m2 / s 25 x 10-6 43 x 10-6 70 x 10-6 3 flash point in open cup, ° C 145 152 172 4 mechanical impurities,% by weight 0.01 0.03 0.27 20 5 water content by weight 0.01 4, 0 0.12 6 fuel content, i% by weight 2.4 3.2 3.2 1 25

Table III shows the chemical composition of the used engine oil.

Table III

30 No. Hydrocarbons Hydrocarbon content,% by weight __ oil type 1 Paraffin-naphthenic (1) (2) (3) hydrocarbons 70.0 53.2 53.2 2 Aromatic hydrocarbons 25.0 34.9 34.9 35 3 Resins 3.0 7.2 7.2 4 Asphaltenes, carbenes and carboids 2.0 4.7 4.7 10 78722 The properties of the starting asphalt concrete and the asphalt concrete of the present invention are shown in Table IV; and asphalt concrete, type of oil and amount of reducing agent in Table IV a.

5

Table IV

Compressive strength MPa Water- Long-term j Temperature, ° C water resistance 10 No. 20 50 0 coefficient coefficient 1 2.4 + 0.2 5.2 + 0.3 10 + 0.4 0.91 _0.86_ 2 1.7 + 0.2 4.0 + 0.2 8.5 + 0.4 0.99 0.86 3 1.3 + 0.1 3.3 + 0.2 7.3 + 0.3 0.98 0.94 15 4 0.85 + 0.2 2.7 ± 0.2 5.1 + 1.0__1.00__1.00 5 1.6 + 0.1 4.5 + 0.3 8, 9 ± 0.3 0.99 0.96 6 1.1 + 0.1 3.8 + 0.2 7.1 + 0.2 1.0 0.95 7 1.0 + 0.1 3.2 +0.2 6.8 ± 0.2__1 ^ 0__M) _ 8 1.3 + 0.1 4.2 + 0.3 8.7 ± 0.3 1.0 0.98 20 9 1.1 + 0 .2 3.3 ± 0.1 7.1 + 0.3 1.0 1.0 10 0.95 + 0.1 1.9 + 0.3 6.6 ± 0.2 1.0 0.97

Table IV a 25 i ------ 1 i Amount of asphalt concrete and oil Reducer,

In: o type ^ * weight% / * * 1 starting material asphalt concrete _____ I_ 30 2 0,3 3 1 0,6 _4____0_j_9_ 5 0,3 6 2 0,6 35 _7_______0_t9__ 8 0,3 9 3 0,6 10 ___ 0 # _9__ n 78722

References in Table IV a: *) the type of oil mentioned in Table II **) the water impregnation of the starting asphalt concrete was 1.9 + 0.4% by volume.

5 The values presented show that in the "hot" asphalt regeneration of tibetone, the properties of the oils in the group of waste engine oils, with the recommendation of their values (including viscosity), have little effect on the properties of the regenerated asphalt concrete.

10 An examination of the modulus of elastic modulus and shear strength of asphalt concretes regenerated using different oils in the group of treated motor oils also confirms the above finding.

A study of the deformation properties of asphalt concrete after thermal hardening, which corresponds to the aging of the road surface under the influence of weather and climatic conditions, shows that they change in the same way regardless of the type of oil in the recommended viscosity range.

Example 3 An asphalt concrete pavement containing 35% by weight of 5/10 mm crushed stone and used for 8 years was rotary plowed by the cold method. 0.4% by weight of motor oil was added to the resulting mixture with stirring. All operations, including addition of the reducing agent, mixing and preparation of the samples, were performed both without heating and with heating to 50 ° C and 130 ° C.

The properties of asphalt concrete prepared at the given temperatures are shown in Table V.

Table V

30 ___

No. Property___ Mixing temperature, ° C

Compressive strength MPa, __temperature ° C__20J__20__50__130 1 50 0.9 + 0.1 0.7 + 0.1 0.8 + 0.1 0.9 + 0.1 35 2 20 4.1 + 0.1 2.9+ 0.1 3.7 + 0.1 4.4 + 0.00 3 0 5.7 + 0.1 4.9 + 0.3 5.5 + 0.3 6.2 + 0.1 4 water resistance factor__0, 56_0.69 0.81_0.98 *) starting material mixture without reducing agent 12,78722

As can be seen from the table, heating the asphalt concrete with the addition of a reducing agent improves its physico-mechanical properties.

Example 4 Asphalt concrete samples were prepared from an asphalt concrete mixture obtained from the surface of an asphalt concrete pavement after heating and removal. The composition of the asphalt concrete, determined after bitumen extraction, was in% by weight: 10 crushed stones 34 sand 55 mineral sand 11 bitumen, more than 100% of the mineral mixture 5.8 15 Samples were prepared by heating the asphalt concrete mixture to 110 + 10 ° C 0.4% by weight of used engine oil and by sealing. The reducing agent was added with or without stirring.

20 The properties of asphalt concrete are presented in Table VI.

Table VI

Property__About properties of asphalt concrete 25 Addition of starting material-reducing agent asphalt concrete mixed- ___mixing matt_ water resistance factor 0.81 0.90 0.85 30 long-term water resistance factor 0.74__0.86_0.78

The values shown show that mixing the mixture with a reducing agent improves the corrosion resistance of asphalt concrete.

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Example 5

A test section was constructed and paved in accordance with the invention. The following operations were performed: 5 - heating the regenerated coating to an average temperature of 110-10 ° C; - grinding, addition of used engine and tractor waste oil as a reducing agent in amounts of 0.0 to 1.2% by weight, based on the amount of asphalt concrete, mixed with the ground mixture; 10 - smoothing and compaction of the resulting mixture.

The test results for the samples taken during the preparation of the road surface are shown in Table VIII. These are the averages of 5 samples obtained at different points in the test section.

15 Table VII

_Features_ specific water impregnation swelling of the pulp 3 no. Weight, q / cm_volume -% _ vol.% 20

Asphalt concrete without reducing agent 1 2.38 + 0.1 2.3 + 1.8 0.3 + 0.1

Asphalt concrete with reducing agent 2 2.39 + 0.02 1.5 + 0.8 0.2 + 0.1 25________

Property No. compressive strength, temperature ° C long-term water resistance _50_20_0_-10_factor_ 30 Asphalt concrete without reducing agent 1 0.8 + 0.4 5.4 + 1.2 10.5 + 2.3 3.11 + 0.1 10, 93 + 0.13

Asphalt concrete with reducing agent 2 0.7 ± 0.4 4.2 ± 1.0 9.1 + 1.1 9.7 ± 1.6_0.99 ± 0.07 78722 14

As can be seen from the table, most of the values for asphalt concrete prepared using the reducing agent of the present invention were improved and the heterogeneity of the prepared pavement was significantly increased (the coefficient of variation of some physicomechanical properties was reduced).

Two years of experience in road section maintenance in heavy traffic conditions gave the following results: 10 - the road surface was undamaged; - the changes in the flatness of the road section were the same as those of the section built without the reducer; - the number of stress fractures was half the number that occurred on a section of road built without a reducing agent.

Claims (4)

15 78722 A method for regenerating asphalt concrete by grinding asphalt concrete and adding a reducing agent to the resulting asphalt concrete mixture, characterized in that 0.1 to 1% by weight of used motor oil, based on the weight of the asphalt concrete, is used as the reducing agent. Process according to Claim 1, characterized in that the kinematic viscosity of the engine oil is 25 x 10 6 to 70 x 10 2 m 2 / s at a temperature of 50 ° C. Method according to Claim 1 or 2, characterized in that the asphalt concrete is heated to a temperature of 50 to 130 ° C before grinding and / or after grinding. Process according to one of Claims 1 to 3, characterized in that the reducing agent is added to the asphalt concrete mixture by mixing.