RU2798369C1 - Cold asphalt concrete preparation technology - Google Patents

Abstract

FIELD: road construction.

SUBSTANCE: invention relates to a method for producing a cold asphalt concrete pavement for highways. A method for producing a cold asphalt concrete pavement, which consists in introducing a filler and a water repellent stabilizer in the form of elemental sulphur of the Tengiz gas processing plant in a cold state into a previously partially dehydrated plasticizer-solvent in the form of oil sludge with intensive mixing, followed by heating and temperature control at a temperature of 110-120°C, after which a binder preheated to the same temperature is added (bitumen) until a homogeneous mixture is obtained.

EFFECT: improving the indicators of waterproofing properties such as water saturation, swelling, long-term water resistance and caking of cold asphalt concrete pavement, as well as in reducing energy and labour costs for its preparation and expanding the raw material base of mineral components from industrial waste, which reduces the likelihood of environmental risk and allows rehabilitate the areas of their deposition.

1 cl, 2 dwg

Description

The invention relates to road construction, namely to the technology of asphalt concrete mixtures for the repair of road surfaces, and can be used to produce cold asphalt concrete with simultaneous disposal of oily waste - oil sludge.

Asphalt concrete mixtures are known, the preparation of which consists in modifying heated bitumen with sulfur-containing waste, and then the resulting composite binder is mixed with mineral materials: waste from grinding stone facing slabs and ash and slag waste (Author's certificate No. 1565862, USSR, C08L 95/00, Method for preparing asphalt concrete mixture. Bull. N 19. 1990). Such asphalt concrete mixtures are distinguished by increased heat resistance ( _Ktherm = 1.82-1.87), frost resistance ( _Kmrz = 0.73-0.75) and long-term water resistance ( _Kdl.water = 0.82-0.85) (U.S. Patent 4,882,373, MKI ⁴ C08K 3/24, C08L 53/02/ Moran Lyle E., Exxon Research and Engineering Co. - N 232210; Application 08/15/88; Published 11/21/89; NKI 524/68).

The closest in technical essence and the achieved result is an asphalt concrete mixture (Author's certificate No. 1735331, USSR, C08L 95/00. A.S. Barankovskiy, V.A. Khrushchev and others // Asphalt concrete mixture. Bull. N 19. 1989) , which includes bitumen, coarse (crushed stone) and fine (sand) aggregates. Applicants recommend coke breeze containing sulfur impurities as a mineral filler. Such an asphalt concrete mixture is distinguished by increased waterproofing properties: water saturation - 1.1-1.2% and water resistance - K _water \u003d 0.94-0.98, as well as improved deformation characteristics: heat resistance (K _thermal \u003d 1.7-1.8 ) and crack resistance ( _Ktr = 1.6).

The disadvantage at the stage of preparation of such asphalt mixtures is the need for preliminary grinding of coke breeze for 1.5-2 hours, which requires significant energy and labor costs and leads to an increase in the cost of asphalt concrete.

The technical result is to improve the indicators of waterproofing properties: water saturation, swelling, long-term water resistance and caking of a cold asphalt concrete road surface, as well as to reduce energy and labor costs for its preparation and expand the raw material base of mineral components from industrial waste, which reduces the likelihood of environmental risk and allows to rehabilitate their deposit areas.

Technical result is achieved by for the development of cold asphalt concrete pavement with improved indicators of waterproofing properties, as well as reducing energy and labor costs for its preparation and expanding the raw material base of mineral components, the initial composition for the preparation of cold asphalt concrete was selected: crushed stone with a fraction of 5 mm., sand with a fraction of 0-5 mm, oil sludge from the Atyrau oil refinery - 1.0-3.0%, bitumen grade BN 90/130 (with a conditional viscosity according to a viscometer with holes with a diameter of 5 mm at 70-115 ° C according to GOST 11955-82), limestone mineral powder of the Inderbor deposit (Atyrau region) with fraction 0.3 mm., elemental sulfur in the form of a stabilizer-water repellent of the Tengiz gas processing plant 8.8-11.3%.

An unconventional source of hydrocarbons can be a variety of oil production and refining wastes, in particular, oil sludge. An equally important aspect of the disposal of these wastes is the solution of environmental problems associated with their storage. At oil refineries in Kazakhstan, hundreds of thousands of tons of oil sludge are annually accumulated in storage ponds.

The composition of these wastes is quite diverse: they contain (% wt.) 10-56% of oil products, 30-85% of water, 1.3-46% of mineral impurities.

The oil sludge of an oil refinery is formed in the process of industrial wastewater treatment and is a flooded dark-colored pasty mass, which consists of crude oil and products of its processing (20-14%), fine mineral particles (24-34%) and water (52-56% ). The mineral part contains aluminum, iron, calcium, magnesium hydroxides, calcium and magnesium carbonates and silica.

The achievement of the specified technical result is ensured by the technology for preparing an asphalt concrete mixture to obtain a cold asphalt concrete road surface, which includes: adding 3% oil sludge to a partially dehydrated plasticizer-solvent in the form of oil sludge (containing, wt. % (see Table 1 in the graphic part): oil products 75, highly dispersed mineral impurities 3.0, sulfur 4.2 and water bound with crude oil) with intensive mixing of the filler containing crushed stone fr. 5 mm 30, sand fr. 0.5-5 mm 40, limestone mineral powder fr. 0.3 mm 12.3 and stabilizer - water repellent in the form of elemental sulfur 8.8, followed by heating and thermostating at 110-120 degrees. With the addition of bitumen 5.9 then heated to the same temperature until a homogeneous mass is obtained. Four more experiments were carried out using this technology, taking into account changes in the composition of the added components. The result of the study is presented in table 2 (see the graphic part).

As a result of the data obtained, the technological modes of preparation and testing of asphalt concrete meet the requirements of GOST 9128-97 "Asphalt concrete mixes, road and airfield, tar concrete". According to the requirements of GOST 9128-97: the compressive strength at a temperature of + 20°C of a dry sample is 7 MPa and at a temperature of + 20°C of a water-saturated sample is 8 MPa; water saturation by volume - 5-9%; swelling by volume 2.0%; water resistance coefficient 0.65; caking by the number of strokes is not more than 10.

. As can be seen from the data in Table 2 (see the graphic part), asphalt concrete (compositions No. 2, 3, 4) prepared on the proposed components also has improved waterproofing performance compared to the requirements of GOST 9128-97 for cold sandy asphalt concrete of the type

.

This is facilitated by a more complete transfer of bitumen from a bulk to a structured state due to the lower viscosity of sulfur, as well as the plasticizing effect of oil sludge and, as a result, a decrease in surface tension. Structured bitumen, as you know, is characterized by a slow aging process, has high adhesive and cohesive properties.

It should be noted that composition No. 5 does not provide a significant increase in water resistance and caking. Obviously, this can be explained by the insufficient amount of oil sludge, which, as noted above, has a plasticizing effect and imparts hydrophobic properties. In composition No. 1, on the contrary, excess oil sludge increases the proportion of plastic deformation, which significantly reduces the strength index. Optimal results that meet the goal are shown on the compositions No. 2, 3, 4.

From the analysis of the results, it follows that the water saturation of cold asphalt concrete (by 1.0-1.2 times) and swelling (by 1.1-1.3 times) significantly decreased, and the water resistance coefficient increased (by 1.0-1.2 times ) in comparison with the requirements of GOST 9128-97. The caking of the developed asphalt concrete according to the number of impacts is 9, 8, 7, 6, 5.

Thus, the proposed technology for the development of cold asphalt concrete provides savings in the binder - bitumen.

The developed cold asphalt concrete can be transported over long distances without the risk of losing or changing their consumer properties. Also, thanks to the use of cold asphalt concrete, the repair season is extended to a temperature of minus 17 ° C, while ensuring high mobility and efficiency of repair work.

The economic effect lies in the fact that instead of diesel fuel in the proposed composition, oil sludge-plasticizers are used as a component of a bituminous binder to produce cold asphalt concrete, and elemental sulfur is used as a stabilizer - a by-product of the Tengiz gas processing plant.

Thanks to this tandem, water saturation, water resistance and compressive strength are improved, which leads to a reduction in the cost of cold asphalt concrete, and, importantly, the organic component of oil sludge reduces the swelling of cold asphalt concrete.

Claims (1)

A method for producing a cold asphalt concrete pavement, which consists in introducing a filler and a water repellent stabilizer in the form of elemental sulfur of the Tengiz gas processing plant in a cold state into a previously partially dehydrated plasticizer-solvent in the form of oil sludge with intensive mixing, followed by heating and temperature control at a temperature of 110-120 ° C , after which a binder preheated to the same temperature is added - bitumen until a homogeneous homogeneous mixture is obtained.

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