Real-Time Temperature Modeling in Expansive Pavement Subgrade in Texas

Behavior of expansive subgrade is influenced by the role of temperature variation with time. Temperature gradients can generate moisture flow in subgrade which ultimately results in variation of shear strength and hydraulic conductivity. While experimental set up have asserted the weakening of clay with increasing temperature, distressed field performance is also observed with temperature variation. In the case of low-volume load, especially, the asphaltic layer, whose stiffness decreases with increasing temperature, serves more as a surface seal than as the main load carrying component. As such, the behavior of the subgrade layer in response to temperature variation is of great interest. Accurate measurements of soil temperature can be obtained through soil sampling and testing; however, this process can be extensive and costly. Thus, developing models that can accurately predict the temperature profile in an expansive subgrade becomes of great interest. The objective of the current study is to develop temperature models using real-time field monitoring data from hot mix asphalt roads in North Texas. Subgrade soils were instrumented using temperature sensors up to various depths. The results obtained from this study produced a temperature prediction model that was dependent on depth and day of the year. The squared correlation coefficient between the observed and predicted soil temperature was around 0.70. Application of the developed models could allow for noninvasive estimation of the response of soil strength and stiffness properties due to variations in temperature.