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Teltayev B.,Kazakhstan Highway Research Institute
International Journal of Pavement Research and Technology

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. Source

Oliviero Rossi C.,University of Calabria | Spadafora A.,University of Calabria | Teltayev B.,Kazakhstan Highway Research Institute | Izmailova G.,Kazakhstan Highway Research Institute | And 2 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects

Polymer modified bitumen (PMB) is used extensively in thin asphalt surfacing and seals in order to improve specific performances. However, the performances of PMB are not easy to demonstrate with the conventional methods, such as penetration test, softening point etc. In order to a better evaluation, different characterization methods are needed rather then ordinary empirical rheological tests. This work deals with the characterization of linear copolymer styrene-butadiene-styrene (SBS) and SBS+polyphosphoric acid (PPA) modified bitumen by using conventional as well as advanced methods on bitumens at different ageing steps and temperature. Fundamental rheological tests, based on a state of the art dynamic shear rheometer in the temperature range from -30°C to +160°C and advanced 1H magnetic resonance relaxometry analysis to evaluate the effect of modifiers on the bitumen structure, were used. Moreover, morphological analysis by scanning electron microscope (SEM) was performed on neat and modified bitumen and the effect of the filler addition on the supra-molecular organization of the bituminous binder was also investigated. © 2015 Elsevier B.V. Source

Teltayev B.,Kazakhstan Highway Research Institute
International Journal of Pavement Research and Technology

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. Source

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

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. Source

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

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. Source

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