Bitumen-concrete mixture on nano-modified binder

FIELD: chemistry.

SUBSTANCE: bitumen-concrete mixture contains crushed rock, sand and oil bitumen BND 90/130, nano-modified with a mechanically activated mixture of rubber crumbs with an additive, where the bitumen is modified using rubber crumbs with size of 0.25 mm and the additive is natural zeolite, with the following ratio of ingredients, wt %: said bitumen 93.0 of the weight of the rubber-bitumen mixture, said crumbs 7.0 of the weight of the rubber-bitumen mixture, natural zeolite 2.0 of the weight of the rubber crumbs.

EFFECT: high plasticity at subzero temperatures.

1 ex, 6 tbl

 

The invention relates to road sector to receive materials road construction purposes with the use of binder bitumen using as a modifier of bitumen rubber crumb from waste rubber General, including tire purpose, which mechanoactivation together with the nanozeolite, with the aim of developing the most cost-effective asphalt mix with the best physical and mechanical properties while simultaneously addressing the pressing issues of the disposal of used tires and ecological environmental protection.

The level of technology

It is known (1. Ivanov S.R., M. Kruglov, Platonov, O., Radov BN. The modern state of thermal methods of processing of waste tires and rubber waste. - M., 1985, 2. Smetanin VI Protection of the environment from the wastes of production and consumption. - M.: Kolos, 2003. - 230 S.)that at the time of loss rubber products their performance itself polymer matrix undergoes relatively small structural changes and can be used for recycling.

The possibility of using crumb rubber in asphalt concrete (AB) is reflected in (3. "Manual for the construction of asphalt concrete pavements and bases for roads and airfields". - M.: The Ministry Of Transport Construction, 1991). In this case, the decrease in dynamic hcpa is istia the underlying layers and decreases the ability to copy cracks and other defects overlapped layers and addressed the issue of recycling of waste rubber.

Bitumen produced for the construction industry, most of them do not meet modern requirements for binding materials. One of the most important ways to increase the longevity and quality of such materials was the introduction in their composition various additives to improve the inherent bitumen properties and modify them into practice direction.

Famous inventions (4. Gorelik R.A., Balyberdin V.N., Blind BM, Lerner M.I. Modifying composition for asphalt mixtures and method for producing a modified asphalt mixture. EN 2377262 and 5. Gorelik R.A., Balyberdin V.N., Blind BM, Lerner M.I. Modifying composition for asphalt mixes. EA 201001076 A1), in which the asphalt mixture contains standard components: screening crushing of gravel, sand, mineral powder and oil bitumen. As modifying additives used active rubber powder with a particle size of not more than 0.8 mm, obtained by thermo-mechanical grinding of the rubber vulcanizate. However, they also contain additional components: metasilicate calcium needle structure, the epoxy resin nitrosoamine compounds, phenolic resin and/or rosin, which are interconnected in a ratio by weight %: metasilicate calcium needle structure 24, the resin is epoxy - 2, nitrosoamine connection - 1, phenol resin and/or rosin - 4, vulcanized rubber (crumb rubber) - 69, in the following ratio: standard components by mass % to 98.5-99,5, additional components by weight % 0.5 to 1.5.

The technical result - the reduction of the temperature sensitivity and the increase in fatigue life with increasing water resistance, frost resistance, resistance to impact of water-salt solutions, reducing viscosity and improving the ductility of asphalt mixtures at low temperatures.

The disadvantages specified composition should include a complex process and costly modifying additives.

Closest to the technical essence and the achieved result to the claimed composition is a mix asphalt (6. Khristoforova A.A., Sokolov PPM, Lebedev A.V., M. Davydova, N.M. Makarov, Morova L.Y. nano-modified asphalt mixture. EN 2466161)containing rubble, sifting gravel, sand fraction, petroleum bitumen, in which the oil bitumen modified mechanically activated rubber crumb (RK) size 0.75 mm and nanospider magnesium in the ratio in percentage composition:

Bitumen grade BND 90/130100%
Crumb rubber7% by weight of bitumen
Nanospider magnesium5% by weight of bitumen

The disadvantage of this composition include high cost nanospider magnesium.

Object of the present invention to provide a binder material, the technical result which is an improvement of the operational characteristics of the material for roads, economic benefit and environmental protection.

Disclosure of inventions

For preparation of asphalt was applied petroleum bitumen grade BND 90/130 (hereinafter bitumen). In the present invention as bitumen modifier selected crumb rubber from waste tires received at the cutting mill using a 0.25 mm sieve, mechanically activated in conjunction with natural zeolite.

Zeolites are widely spread minerals, are used due to the nanoporous structure as adsorbents, molecular sieves, catalysts, fillers, etc. the Possibility of their use in asphalt mixtures due to the high adsorption ability and activity, reflected by mechanical activation, which gives the opportunity to improve the interaction on the phase boundary "bitumen - rubber crumb".

is mehanoaktivny was performed in a planetary ball mill with a centrifugal acceleration of 60 g, when the ratio of the feed material" : "grinding media" 1:15 for 2 minutes.

Mechanical activation leads to dispersion of rubber crumb (table 1) and zeolite (table 2).

Table 1
Fractional composition of powders rubber crumb according to sieve analysis
Activation min
02
The area dimensions, mm0-0,3350,335-0,710,71-11,0-1,4>1,40-0,3350,335-0,710,71-11,0-1,4>1,4
Fraction of particles, %5,054,132,36,71,98,687,12,21,4 0,7

Table 2
Fractional composition of the powders of natural zeolites according to dynamic light scattering
Activation min
02
The area dimensions, m(0,15-1,75)·10-3(30-169)·10-9(169-3000)·10-9
Fraction of particles, %100%694

The behavior of the bitumen is modeled test for embrittlement temperature and the softening temperature, the difference of which conditionally expresses deformation ability, when the binder is in a viscoplastic state. Therefore, when the standard test of modified binders, special attention was paid to the determination of the softening temperature and the temperature embrittlement of the bitumen.

As can be seen from table 3, the softening temperature of the original bitumen does not meet the requirements of GOST 11506-73 (not lower than 43°C). Modification of bitumen non-activated rubber crumb allows p is the increase of the softening temperature of 4°C, the technology of mechanical activation increases the rate of 6°C.

Table 3
The softening point of bitumen and bitumen, modified rubber crumb
Softening point, °C
Nonactivated crumb rubberActivated crumb rubber
Bitumen40
bitumen + crumb rubber 0.25 mm4446

Research brittle bitumen (table 4) showed that all values correspond to GOST 11507-78. The embrittlement temperature of bitumen modified rubber crumb, mechanically activated in conjunction with the zeolite is reduced by 2° relative to the requirements of GOST.

Table 4
The embrittlement temperature of the bitumen and bitumen, modified rubber crumb
Pace is the atur fragility, °C
Nonactivated crumb rubberActivated crumb rubber
Bitumen-19
bitumen + crumb rubber 0.25 mm-17-20

Thus, it is shown that the use of mechanically activated rubber crumb allows you to extend the interval of plasticity standard bitumen at 7°C.

Below are the results of tests of the main physico-mechanical properties of modified asphalt mixtures (table 5).

Table 5
Basic physical and mechanical properties of asphalt concrete
Seriespm, g/cm3pmM, g/cm3VpaboutpM, %Vpabout p0, %W %RSGMPa/kNRpMPa/kN
AB basic2,282,1319,1613,480,856the 5.251,79
RK 0.25 react. + zeolite react.2,332,1717,4411,650,5305,64/-1,33/-
RK 0,25 act + zeolite act.2,342,1817,06at 11.250,4595,59/-1,35/-
Known analog-----5,4/a 21.54,4/21,8
where: pm, is the average density uplatnena what about the material, pmM- the average density of the mineral, VMthe porosity of the mineral, V0residual porosity, W is the water saturation, RSG- the limit of compressive strength, Rp- the limit of the tensile strength at the split.

It is seen that the porosity of the samples containing the modified rubber crumb, is reduced to 17%. The same dynamics improvements observed for the density of the compacted material and the water saturation. Lowest videosystem have samples containing modified rubber crumb (lower than the rate of typical asphalt 46%). Strength characteristics change slightly.

On the basis of the conducted research was developed formulation of modified asphalt mixtures (table 6) and technology the introduction of modifying additives in asphalt concrete mixture.

Table 6
Composition of modified asphalt mix
Component nameThe content of component %
offer Known analog
Bitumen BND 90/13093,0 by weight rubber-bitumen mixture100 wt.%
Crumb rubber7,0 by weight rubber-bitumen mixture7 by weight of bitumen
Zeoliteto 2.0 by weight of rubber crumb-
Nanospider magnesium-5 by weight of bitumen.

Example:

To obtain the claimed asphalt mix on nanomodified binder per 1 ton of the mineral part (gravel 300 kg, sifting rubble 500 kg, sand 200 kg) binder ingredients are taken in the following amounts: petroleum bitumen BND 90/130 from 65.1 kg; crumb rubber obtained using a 0.25 mm sieve - 4,802 kg; natural zeolite - 0,098 kg of Rubber crumb in conjunction with pre-digidrirovanny zeolite activated in a planetary ball mill with a centrifugal acceleration of 60 g, the ratio of the loaded material : grinding media 1:15 for 2 minutes. The bitumen is heated to a temperature of 120-130°C, is introduced into rubber crumb with zeolite under stirring to homogenize the knitting. Mineral components of the asphalt mix, adesina in the mixer, heated to a temperature of 130-140°C and mixed with modified binder. Next mix asphalt placed on the prepared base pavement and pressed.

The mixture is prepared in accordance with the requirements of the state standard for technological regulations. Additional process steps in the standard process flow are preliminary mechanical activation of crumb rubber in conjunction with natural zeolite in the activator type planetary ball mill and the introduction of modifying additives to the bitumen during mechanical mixing.

Thus, it is shown that the modification of bitumen activated rubber crumb can improve the properties of asphalt concrete based on it. The most important especially for regions with large annual and daily temperature extremes and frequent crossing the freezing point of water (0°C) is a significant reduction of water saturation and the interval extension of the plasticity of the binder.

Asphalt mixture containing the crushed stone, screenings of crushed stone, sand and petroleum bitumen BND 90/130, nanomodified mechanically activated mixture of rubber crumb additive, characterized in that for the modification of bitumen using rubber crumb size 0.25 mm, but as a Supplement - natural zeolite, in the following ratio of ingredients, wt.: the specified bitumen 93,0 by weight rubber-bitumen mixture, this crumb of 7.0 by weight rubber-bitumen mixtures, natural zeolite to 2.0 by weight of rubber crumb.



 

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