Introduction. The introduction to the paper highlights the aspects of the analysis of results of flexible road pavement load test which shall be related to the temperature-dependent characteristics of asphalt concrete.
Problem statement. The issues of the paper concern the questions of prediction of temperature within the asphalt concrete layer by the BELLS mathematical model and also the adjustment of the flexible pavement’s assessment and design parameters to the reference temperatures.
Purpose. The goal of the paper is to analyze the main provisions of the BELLS model and also provisions for modeling the basic temperature-dependent parameters taken into account when designing the flexible road pavements and which are based on the results of the construction stiffness and deflection basin measurements that were performed through the FWD (Falling-Weight Deflectometer) test.
Results. The effect of temperatures on the flexible road pavement materials’ deformational properties was reviewed with separating crucial characteristics such as asphalt concrete modulus and basin shape factors obtained using the road pavements load tests results.
Also the analysis of main provisions of the model for asphalt concrete layer temperature prediction was performed and the evolution of the on the BELLS equation based model with standard calculation algorithm was described which considers two sin-function with the offset to cover the different duration of the stages of asphalt concrete temperature rising and falling in a construction through the whole day.
Within the mechanistic-empirical approach to the road pavement design, the modeling of temperature-dependent parameters such as asphalt concrete moduli, and basin shape factors, and deflection in the point of loading were briefly analyzed. Also, the examples of the selection of significant parameters for calculation were reviewed in accordance with the characteristics of a construction, namely the asphalt concrete layer thickness, stiffness of the subgrade and the object’s geography. The attention was paid to the questions of the BELLS model verification on the objects with various climatic conditions.
Conclusions. Within the contemporary practice for the highway construction, the road pavement load tests are the integral part of the flexible road pavements assessment and design requiring along with that the precise data regarding temperatures in the asphalt concrete layer according to the test conditions.
The deflection testing procedure with usage the FWD device questions the efficiency of the measurement of temperatures in an asphalt concrete layer giving preference to the temperatures prediction.
The highly effective one is the prediction of these temperatures via the model based on the 18-hr cycle of rising and falling of temperatures of asphalt concrete in a construction through the whole day as it was standardized by ASTM.
The actual direction of the implementation of such a standard model and related approaches to the road pavements assessment and design in Ukraine should be the scientific-engineering support for construction of highways with further verification and, expectedly, enlargement of scopes of that model application.
