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Boborazhabov Bakhodir Nasriddin yzli, Independent applicant, assistant at the Tashkent Institute of Chemical Technology Vapaev Murodjon Dusummatovich, doctoral candidate, basic doctoral studies of the department «Technology of plastics and high-molecular compounds» Tashkent Institute of Chemical Technology Ahmadzhonov Sardor Akhmadzhonovich, master of Tashkent Institute of Chemical Technology Ibadullayev Akhmadzhon, doctor of Technical Sciences, professor, envious of the department «Chemical technologyof oil and gas processing»,
Tashkent Institute of Chemical Technology.
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STUDY OF PAVING BITUMENS PROPERTIES MODIFIED BY COMBINED ADDITIVES
Abstract: In this article, the effect of combined modification of road bitumens on complex properties of the composition is considered. The increase in the softening temperature and the physical and mechanical properties showed an optimal modifier content.
The effect of combined modification of paving bitumen on the complex properties of the composition is analyzed. The increase in softening temperature, physical and mechanical properties is shown and establishes the optimal content of the modifier.
Keywords: bitumen, non-standard, composition, modifier, recycled rubber, crumb, technology, paving bitumen.
Introduction. Use of recycled materials as well as fuel for determining the breaking point of petroleum bitumen)
and energy resources is of crucial importance in the creation device; GOST 11505-75 "Petroleum bitumens. Method for
and improvement of existing road-building composite materi- determination of ductility" using DB-2M (AB-2M) ductilom-
als and technologies [1]. eter; GOST 11506-73 "Petroleum bitumen. The method of
Today, the research in improving the quality and durabil- the determination of softening point by ring and ball" using
ity of pavement surfacing is focused on modification of bitu- KISH-20 (KHffl-20 - automatic apparatus for determining
mens by using various additives to improve the basic prop- the softening point of petroleum bitumen and bituminous
erties of asphalt homogeneity, strength, resistance to frost, materials); GOST 11501-78 "Petroleum bitumens. Method
cracking, moisture and high temperatures [2]. for determination of depth of needle penetration" using the
This article presents the results of studies on the modi- penetrometer PN-10 (nH-10).
fication of the properties of paving bitumen with combined Results and discussion. Tables 1 and 2 show the quality
additives obtained on the basis of recycled rubber and gas- data of the modified bitumen. The analysis of the quality data
pyrolysis resin. of the modified bitumen has established that modifying the
Subjects and methods of research. Modified BND (Pe- BND 90/130 bitumen with the additives obtained allows us
troleum paving bitumen) 60/90 paving bitumen with com- to improve its quality of almost all of its parameters.
bined additives in the following mass ratios: recycled rubber The softening temperature and the breaking point tempera-
(R) to gas-pyrolysis resin (GPR): 1.5:1; 2:1; 2.5:1, and BND ture of modified bitumens increase, high values of penetration
40/60 paving bitumen to ensure quality of BND 60/90 bitu- are achieved at 0 °C, and the values of softening temperature
men grade - with high gas-pyrolysis resin content combined and weight loss of bitumens after heating are improved. Adhe-
additives in the following mass ratios (R: GPR): 3:1; 4:1. sive properties of bitumen modified with a combined additive
Studies of the properties of bitumen were carried out in (R + GPR) in a mass ratio of components in it 1.5: 1.0 and 2: 1.
accordance with the following GOSTs: GOST 11507-08 "Pe- BND 60/90 bitumen, modified with combined additives, had
troleum bitumen. Method for determination of Fraas break higher values of quality parameters compared to the require-
point" using the ATH-20 (ATX-20 - automatic apparatus ments of the standard. The resulting combined additives contain
crumb rubber, which forms an independent dispersed phase in modified bitumen, the dependency of the stability factor (Fig-bitumen, which can affect the sedimentation stability of bind- ure 1) and the particle sizes of the dispersed phase (Figure 2) ers during operation, transportation and storage. Therefore, for on the content of the combined additives were investigated.
Table 1. - The quality data of BND 90/130 paving bitumen, modified with combined additives, obtained on the basis of recycled rubber and gas-pyrolysis resin
Additive ra-tio,% mass Temperature, °C Penetration, 0.1mm Heating mass change ratio,% mass. Heating softening temperature change, °C Adhesion
softening breaking at 0 °C at 25 °C
0 45 -35 27 79 0.80 6 3
Crumb rubber: gas-pyrolysis resin = 1.5:1.0
2 52 -31 33 79 0.60 3 2
4 63 -25 33 80 0.65 3 2
6 78 -26 35 81 0.65 3 2
8 89 -23 35 81 0.70 4 2
Crumb rubber: gas-pyrolysis resin = 2.0:1.0
2 54 -27 32 79 0.60 3 2
4 69 -29 39 82 0.70 3 2
6 84 -27 39 83 0.70 4 2
8 94 -28 35 84 0.80 4 2
Crumb rubber: gas-pyrolysis resin = 3.0:1.0
2 53 -35 29 79 0.60 3 3
4 68 -33 26 82 0.70 4 3
6 82 -33 25 83 0.80 5 3
8 86 -41 26 83 0.80 5 3
Table 2. - The quality data of BND 60/90 paving bitumen, modified with combined additives, obtained on the basis of recycled rubber and gas-pyrolysis resin
Additive ra-tio,% mass Temperature, °C Penetration, 0.1mm Penetration index Adhesion
softening breaking at 0 °C at 25 °C
0 55 -11 60 24 0.50 3
Crumb rub ber: gas-pyrolysis resin = 3:1.5
2.2 55 -12 64 64 0.49 2
4.9 65 -14 70 70 0.18 2
7.0 79 -15 72 70 0.11 1
8.9 91 -17 84 74 0.20 1
10.7 88 -17 89 80 0.15 1
11.8 86 -19 88 80 -0.08 2
12.8 80 -20 82 80 0.07 2
Crumb rubber: gas-pyrolysis resin = 4:2
2.4 55 -13 58 58 0.35 2
4.8 67 -15 68 67 0.19 2
6.5 89 -14 90 88 0.27 1
9.0 88 -13 90 87 0.52 1
10.5 72 -17 94 88 0.12 1
11.1 68 -19 92 86 0.01 2
13.0 60 -17 92 86 0.36 2
From the obtained dependencies it was found that with an 2:1, the stability factor of bitumen and the size of the particles increase in the content of the combined additive, 1.5: 1.0 and of its dispersed phase increase. Apparently, this is due to the
increase in the intermolecular interaction forces between the dispersed phase, also formed by large rubber aggregates and the dispersion medium of bitumen at a given ratio of components in the combined additive. With the introduction of a combined additive in bitumen with a mass ratio of components (R + GPR) = 3.0:1.0 in an amount of more than 1% mass, the stability of the system decreases, and the particle size of the dispersed phase has a maximum value with the introduction of 4% mass supplements. This is apparently due to the formation of a coarse-dispersed system due to the increased content of aggregates of rubber crumb in the volume of bitumen.
According to the dependencies shown in the figures, the best composition of the combined additive was established (mass ratio R: GPR = 1.5:1) and its content in bitumen (2-4% mass) in order to obtain thermodynamically stable systems.
The results presented in Table 3 demonstrate the feasibility of using bitumen modified with combined additives (R + GPR) as binders for asphalt concrete mixtures. Asphalt concrete complied with the requirements of GOST 9128-97 in all major quality parameters, and the strength properties and water resistance of asphalt concrete improved significantly.
Figure 1. Stability factor of bitumen modified with combined additives (R+GPR)
Modified 2% mass combined additive consisting of gas-pyrolysis resin in a mass ratio of1.5:1.0 can be recommended as a binder for asphalt bitumen for practical use. The compounding technology of bitumens with a combined additive (R + GPR) allows to improve the properties of low-quality oxidized paving bitumens with the help of cheap elastomeric
Figure 2. Particle size of the dispersed phase of bitumen modified with combined additives (R+GPR)
modifiers (rubber crump), to obtain bitum rubber binders, in which rubber does not decompose, but is evenly distributed in the dispersion medium of bitumen and exhibits its high operational properties in the composition of the new composite material.
Table 3. - The quality of asphalt concrete, obtained on the basis of bitumen, modified with combined additives on the basis of rubber crump and heavy pyrolysis resin
Parameter Basic bitumen Modifier
1% mass R + PR1.5:1.0 2% mass R + PR1.5:1.0 7% mass R+PR1.5:1.0
Compressive strength at 50 °C, MPa 0.9 1.0 1.0 0.9
Compressive strength at temperature 20 °C, MPa 2.4 3.2 3.4 2.9
Crack resistance at splitting ductility strength, 0 °C 4.1 4.2 3.7 3.2
Water resistance, not less 0.78 0.90 0.95 0.90
Water saturation,%, volume 2.0 3.1 2.9 3.2
The results of research of improvement methods of the quality of BND 60/90 paving bitumen, obtained from paraffin tar from the Fergana oil refinery by combined additive. Table 4 presents the main quality parameters of modified bitumen with a combined additive obtained on the basis of rubber crump and gas-pyrolysis resin at a 2:1 ratio by mass.
This ratio of the components in the additive has been selected with the aim of addition of aromatic compounds in the basic bitumen. The research has shown that the obtained modified bitumens had higher values of softening temperature and adhesion index, and the breaking point temperature satisfied the technical requierments.
Table 4. - The quality data of bitumen obtained by oxidation of tar of the Fergana oil refinery, modified with a combined additive (rubber crump and gas-pyrolysis resin in a mass ratio of 2:1)
Additive ratio, % mass Temperature, °С Penetration, 0.1mm Heating mass change ra-tio,% mass. Heating softening temperature change, 0оС Adhesion Plastic range, 0 °С
Softening Breaking at 0 °С at 25 °С
0 44 -36 56 90 0.90 4 3 79.9
1 58 -27 55 75 0.90 4 2 75.1
2 67 -29 53 78 0.90 3 2 76.3
3 78 -27 54 80 0.95 3 2 74.8
4 88 -26 56 79 1.00 3 2 74.1
5 89 -23 57 80 1.10 4 2 71.9
7 89 -24 57 82 1.20 4 2 72.4
Conclusion. The research results indicate the possibility bitumens with a combined additive based on crump rubber of adjusting the basic quality of unbalanced or non-standard and gas-pyrolysis resin for the production ofvarious bitumens.
References:
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