Early age behavior of jointed plain concrete pavements subjected to environmental loads
Studies on deformation characteristics of early-age Jointed Plan Concrete Pavements (JPCP) subjected to pure environmental loading has drawn significant interest as it is believed that the early-age deformation of Portland Cement Concrete (PCC) slab could result in the loss of pavement smoothness and the tensile stresses induced by these deformations could result in early-age cracking. However, the complex interaction of several environmental factors has resulted in difficulties in predicting the JPCP deformation characteristics under environmental loading. Also, the effect of the resulting slab distortion on the initial JPCP smoothness has not been adequately addressed by previous research studies.
In this study, two newly constructed JPCP test sections; one on highway US-34 near Burlington and the other on US-30 near Marshalltown, Iowa were instrumented and monitored during the critical time (seven days) immediately following construction during the summer of 2005. Temperature data and moisture data obtained from both sites were analyzed. The slab deformations associated with temperature and moisture were analyzed using measured vertical displacements and pavement surface profile measurements. Using the longitudinal surface profile measurements from different locations of the test section during the morning and afternoon diurnal cycles, the smoothness indices such as International Roughness Index (IRI) and Ride Number (RN) were computed.
The early-age deformation behavior of instrumented JPCP under environmental loading was simulated using ISLAB 2000 (2.5-D) and EverFE 2.24 (3-D) Finite Element (FE) programs using the equivalent temperature difference concept. The changes in smoothness indices at different measurement times were investigated and compared with those obtained using FE simulations.
This study shows that the early-age deformation behavior of PCC is influenced not only by temperature variation but also by other environmental factors such as the moisture variation, drying shrinkage and temperature condition during pavement construction. Even though it is observed that measurable changes of early-age pavement smoothness do occur between morning and afternoon, these variations are not statistically significant.