Kazakhstan Highway Research Institute

Almaty, Kazakhstan

Kazakhstan Highway Research Institute

Almaty, Kazakhstan
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Teltayev B.B.,Kazakhstan Highway Research Institute | Amirbayev Y.D.,Kazakhstan Highway Research Institute
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences | Year: 2017

Tensile strength of asphalt concretes and polymer asphalt concretes was determined experimentally at low temperatures through two methods in the paper. According to the first method the ends of the sample were fixed inflexibly. Temperature was reduced from +20°C with the rate of 10°C/h till sample damage. Critical stress and temperature were determined. According to the second method samples of asphalt and polymer asphalt concrete are deformed under the scheme of direct tension with constant rate (approximately 1 mm/min) at a constant temperature equal to -20°C till damage. The stress, when the damage of the sample occur (splitting into parts), has been admitted as the tensile strength of material. Prior to testing the samples were previously conditioned for 1, 10, 20, 30 and 40 hours. Test results showed that duration of preliminary conditioning impacts greatly on strength and deformability of asphalt and polymer asphalt concretes. During deformation with constant rate at -20°C tensile strength of all tested asphalt and asphalt concretes decreases with the increase of thermostatic conditioning duration up to 10 hours and further increase of duration does not impact practically on it. Meanwhile the strength decrease of asphalt concretes with bitumens grade BND 70/100 and BND 100/130, polymer asphalt concretes with polymers Elvaloy 4170, Calprene 501 and Butonal NS 198 is 49%, 32 %, 24 %, 25 % and 29 % respectively. During cooling with constant rate the duration of thermostatic conditioning does not impact practically on critical characteristics of asphalt concrete with bitumen grade BND 100/130 and polymer asphalt concrete with polymer Butonal NS 198. For other asphalt and polymer asphalt concretes the critical temperature is reduced with the duration increase of thermostatic conditioning, and critical stress increases. For all tested asphalt and polymer asphalt concretes the reduction of critical temperature at maximum thermostatic conditioning (40 h) is 2-2.5°C. Maximum increase of critical stress, which also complies with maximum duration of thermostatic conditioning (40 h), for asphalt concrete with bitumen grade BND 70/130, polymer asphalt concretes (BND 100/130 + Elvaloy 4170) and (BND 100/130 + Calprene 501) is equal to 28.0 %, 6.1 % and 15.0 % respectively. © National Academy of Sciences of the Republic of Kazakhstan, 2017.


Teltayev B.B.,Kazakhstan Highway Research Institute
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences | Year: 2017

This article shows test results of conventional hot mix asphalt and hot mix asphalt with polymers Kraton and Calprene for fatigue in a regime of controlled strain by the device of four-point bending with loading frequency of 10 Hz and temperature of 10 °C. Dissipated pseudo strain energy, connected with the increase of phase angle and reduce of complex modulus, as well as total dissipated pseudo strain energy were determined. Diagrams of dissipated strain energy changes were made depending on the number of loading cycles. Correlations were stated between the number of loading cycles to failure and constant strain of testing, between the number of loading cycles and total dissipated strain energy at failure. It was found that hot mix asphalt with polymer Calprene has the highest fatigue strength. © National Academy of Sciences of the Republic of Kazakhstan, 2017.


Teltayev B.,Kazakhstan Highway Research Institute | Radovskiy B.,Radnat Consulting
Road Materials and Pavement Design | Year: 2017

The objective of this study was to develop approximate relationships for prediction of the rheological properties and tensile strength of asphalt concrete with conventional bitumen binder to address the low-temperature cracking analysis. The parameters of modified Christensen–Anderson–Marasteanu model for relaxation modulus of bitumen were related with its penetration index and softening point by approximate formulas based on Van Der Poel's nomograph for determining bitumen stiffness. Hot mix asphalt relaxation function has been described by the Christensen–Bonaquist model. Hot mix asphalt tensile strength as a function of loading time and temperature was related to the bitumen stiffness by equation based on Heukelom's data and the Molenaar-Li empirical formula. The strength of hot mix asphalt has been also studied by performing tensile tests at constant strain rate and temperatures. The results were analysed considering the calculated stress increase with temperature drop at various cooling rates. Critical temperature was estimated from comparison of thermal stress and tensile strength of asphalt concrete at constant stress rate. © 2017 Informa UK Limited, trading as Taylor & Francis Group


Teltayev B.B.,Kazakhstan Highway Research Institute
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences | Year: 2017

The paper shows the importance of rocks in modern road construction. The first part of the paper analyzes the technical requirements, demanded by the operating standards of the Republic of Kazakhstan, to the crushed stone and gravel from dense rocks. Standard values are set for losses of the weight of the crushed stone and gravel from rocks for the determination of their grades under indexes of crushability, abrasion and frost resistance. Based on the analysis of the results of laboratory test for the crushed stone from four borrow-pits, located in different regions of the republic, it was determined that there are considerable scatters in values of the loss in weight of the crushed stone within one grade, which achieve 200%. The second part of the paper analyzes the results of experimental determination of occasional, longterm and fatigue strength of the dense fine-grained asphalt concrete, traditionally used in Kazakhstan for road construction, which is prepared with the use of stone materials from the rocks (95.2% of the weight) and bitumen of grade BND 100-130 (4.8%), as well as the dependence of average amount of the thermal cracks on the asphalt concrete pavements on the amount of critical air temperature falls. It is shown that, as a rule, there are considerable scatters in the values of deformation and strength characteristics of the asphalt concrete, which specifies to consider nonhomogeneity of the basic rocks as one of the main causes of these scatters. © National Academy of Sciences of the Republic of Kazakhstan, 2017.


Teltayev B.B.,Kazakhstan Highway Research Institute
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences | Year: 2017

This paper analyzes the fatigue failure of the asphalt concrete pavement of the highway on a macroscopic level. Based on the actual data, obtained on the sections of the real highways, the principle was formulated for the staged fatigue failure of the asphalt concrete pavement. During the analysis of the existing classifications of the fatigue cracks, it was determined that in Kazakhstan the stage behavior of the fatigue cracks was not considered, and in the USA the relation between stages of failure was not established. Similarly to the known phenomena of selforganization in thermodynamics of irreversible processes and dynamics of non-linear systems (synergetics) - the Benar’s effects and division of biological cell, it was proposed to consider the parts of the asphalt concrete pavement as the specific dissipative structures, occurring in critical conditions, and a new regularity of fatigue failure was formulated. The formulated regularity of the staged fatigue failure of the asphalt concrete pavement was explained based on the new proposed scheme of bifurcation with the use of the results of experimental determination of the occasional, cyclic, long-term and residual strength. © National Academy of Sciences of the Republic of Kazakhstan, 2017.


Teltayev B.B.,Kazakhstan Highway Research Institute
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences | Year: 2017

In this paper the fatigue destruction regularity of asphalt concrete pavement, determined before, has been proved by observance of the identified criteria for thermodynamics of irreversible processes – universal Glensdorf- Prigozhin criterion and principle of minimum for production of the entropy of Yu.L. Klimontovich. Values of production of the entropy under impact of vehicle load of various volumes have been calculated from values of stresses and strains in asphalt concrete pavement of the highway. Stresses and strains have been determined with the use of solution of A.K. Privarnikov for multilayer elastic half-space, on the surface of which the vertical static load has been applied and uniformly distributed along the area of a circle. To calculate the stresses and strains the fivelayer pavement structure has been taken, which included two asphalt concrete layers. © National Academy of Sciences of the Republic of Kazakhstan, 2017.


Teltayev B.,Kazakhstan Highway Research Institute | Aitbayev K.,Kazakhstan Highway Research Institute
Indian Geotechnical Journal | Year: 2015

The nonstationary temperature field is modeled by the finite element method. Results of the numerical analysis conform fully with the experimental data. By means of the developed finite element model, temperature variation has been obtained in points of asphalt concrete layers of pavement within one decade of the hottest period in the southern region of Kazakhstan. Using the solution of axisymmetric problem of elasticity theory for the layered media, stresses and deformations in specific points of flexible pavement under loading have been calculated at night period (when asphalt concrete layers temperature is minimum) and at day period (when asphalt concrete layers temperature is maximum). The obtained results showed that depending on temperature stresses and deformations in specific points of pavement change significantly. Therefore correct modeling of temperature field in flexible pavement is important in their designing. © 2014, Indian Geotechnical Society.


Teltayev B.,Kazakhstan Highway Research Institute
International Journal of Pavement Research and Technology | Year: 2015

In this paper a new criterion for determination of cycle number to failure of asphalt mixture at test in controlled strain mode is proposed. The proposed criterion is based on equality of total dissipated energy and total dissipated pseudo strain energy atfailure. The proposed failure criterion is presented in three forms: in energy balance form, in termsof linear viscoelasticity theory and continuum damage mechanics. A new criterion applicability is shown by testing of hot mix asphalt mixture samples on four point bending equipment in controlled strain mode. Comparison of loading cycle numbers to failureof asphalt mixture obtained using the proposed and other often used criteria are carried out. © Chinese Society of Pavement Engineering.


Teltayev B.,Kazakhstan Highway Research Institute
International Journal of Pavement Research and Technology | Year: 2014

Low temperature cracking is one of the prevalent types of hot mix asphalt pavement defects, and there are many methods of its evaluation. In this paper,the indicators of hot mix asphalt pavement low temperature cracking are evaluated by a combined approach, where hot mixasphalt tensile strength at low temperatures has been determined by testing in conditions of deformation with constant rate, and low temperature stress has been calculated based on integral equation of linear viscoelasticity theory. Conditions of aircooling have been considered throughthetemperature falling (cooling) rate. It has been ascertained that for the considered hot mix asphalt at cooling rate from 0.4°C/h to 1.6°C/h,Critical stress and Critical temperature do not depend on cooling rate: critical stress σcr=6.0to 6.2MPa, Critical temperature Тcr=-19to-21°C. The indicator, characterizing the low temperature stress increase rate in hot mix asphalt pavement, at Critical time also does not depend on the cooling rate and has constant value equal to 2.7. © Chinese Society of Pavement Engineering.


Teltayev B.B.,Kazakhstan Highway Research Institute | Aitbayev K.,Kazakhstan Highway Research Institute
Geomechanics and Engineering | Year: 2015

Mathematical model has been developed for determination of temperature field in multilayer pavement and subgrade, which considers transfer of heat by conduction and convection, receiving of heat from total solar radiation and atmosphere emission, output of heat due to the emission from the surface of pavement. The developed model has been realized by the finite element method for two dimensional problem using two dimensional second order finite element. Calculations for temperature field have been made with the programme realized on the standard mathematical package MATLAB. Accuracy of the developed model has been evaluated by comparison of temperatures, obtained theoretically and experimentally. The results of comparison showed high accuracy of the model. Long-term calculation (within three months) has been made in pavement points in accordance with the data of meteorological station for air temperature. Some regularities have been determined for variation of temperature field. © 2015 Techno-Press, Ltd.

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