Difference between in situ flexible pavement measured and calculated stresses and strains

One of the 12 instrumented sections of the Virginia Smart Road was used to compare measured vertical compressive stress and measured transverse horizontal strain under the hot-mix asphalt (HMA) layer induced by a 25.8 kN (5.8 kip) single tire and a 39.5 kN (8.9 kip) set of dual tires to those calculated using layered linear elastic theory. The pavement section is composed of 38 mm (1.5 in.) HMA wearing surface, 150 mm (6 in.) of HMA base mix, 75 mm (3 in.) of asphalt stabilized open graded drainage layer, 150 mm (6 in.) of cement stabilized aggregate layer, and 175 mm (7 in.) of unbound aggregate base. The subgrade is a fill material composed mainly of rocks. Measured stresses were obtained using pressure cells embedded in the pavement during construction. Horizontal transverse strain was measured using H-type strain gauges that were also embedded during construction. Temperature in the pavement layers was measured using embedded T-type thermocouples. Theoretically calculated stresses and strains were obtained using software based on the layered-elastic theory (Kenpave, Bisar 3.0, Elsym5, and Everstress 5.0). In addition, two finite-element approaches were used. Results indicated that the layered elastic theory overestimates pavement responses at low and intermediate temperatures, but significantly underestimates the pavement responses to vehicular loading at high temperatures.