Authors:
Pabitra Rajbongshi; Mitali Saharia; Kh. Lakshman Singh;
Abstract:
Asphalt mix is a visco-elastic material. That is, it exhibits a combination of time-independent stress-strain (elastic) behaviour and time-dependent stress-strain (viscous) behavior under loading. It imparts stress relaxation with time under constant strain and strain enhancement with time under constant stress conditions. Both stress and strain vary with certain phase differences under dynamic loading. Different types of dynamic loading can be used for material evaluation, like sinusoidal, halfwave sinusoidal, haversine, square, halfwave square,… etc. loadings, either at a stress-controlled mode or a strain-controlled mode. This paper aims to characterize the stress (𝜎𝑡) variation for different loading patterns under strain (𝜀𝑡) control condition. Four different types of 𝜀𝑡 are considered with and without rest period. It is observed that the 𝜎𝑡 characteristic is significantly different for different 𝜀𝑡 inputs, for the same strain amplitude and loading frequency. Asphalt
pavement is being subjected to vehicular dynamic loading with rest time and a stress-based shift factor due to the rest period is developed. This study also explores the sensitiveness of stress fluctuation with loading frequency (𝑓) and relaxation time (𝜏) of asphalt concrete, for each loading pattern. It is seen that both 𝑓 and 𝜏 affect significantly the stress characteristics under different loading patterns
Keywords:
Asphalt concrete, Visco-elastic behavior, Dynamic loading, Stress-strain behavior