Evaluating the Longitudinal and the Transverse Horizontal Strains at the Bottom of Hot Mix Asphalt

Horizontal strain at the bottom of asphalt concrete due to repeated traffic loads is the most critical parameter in characterizing fatigue performance of flexible pavement. The study of horizontal strain is thus very important to understand the strain behavior, predict the fatigue life and implement in design and analysis. A total of twelve Horizontal Asphalt Strain Gages (HASGs), six gages oriented in longitudinal direction and the other six sensors oriented in transverse direction are installed at the bottom of the asphalt concrete to measure the horizontal strains in both the longitudinal and the transverse directions for real time traffics. This study investigates these strains using data from the installed sensors. The strains responses for eighteen-wheel vehicles for a couple of days passing between 4:00 pm to 6:00 pm are considered for the study. Results show that the longitudinal strain has both compressive and tensile components and the transverse strain is totally tensile when the wheel is on the sensor’s path and compressive if the wheel totally deviates from the sensor’s path. It is also measured that the transverse strain is 1.18 times of the longitudinal strain.