Development of an early-age behavior model for Portland cement concrete pavements

It has been theorized that the early-age behavior in a Portland cement concrete pavement (PCCP) due to temperature and moisture changes can significantly affect the performance over the service life. During the first 72 hours following construction, the strength of PCC is relatively low, as compared to a mature concrete. During this same period, critical stresses can develop which can lead to damage, and a subsequent loss of performance.;Most existing stress and strength models are too simplistic due to inherent assumptions. This has resulted in a loss of accuracy due to the failure to account for the complex interactions between the numerous mechanisms involved. Therefore, the ideal tool for this type of pavement analysis would allow for flexibility in the large number of inputs that determine these phenomena.;This research focuses on modeling the early-age phenomena of concrete pavements subjected to stresses from moisture and thermal changes. The end result of this project includes the development of a two-part, versatile, comprehensive set of guidelines which provide direction in the proper selection of design and construction variables in order to minimize early-age damage to the PCCP. The first part of these guidelines is qualitative in nature and is based upon past experiences and engineering judgment. They are intended to identify design and construction inputs which are most likely to lead to good behavior during the early-age period.;For the second part of the guidelines, a model has been developed which can predict early-age behavior in jointed plain concrete pavements. This model is used to verify good behavior from the selection of inputs made using the qualitative guidelines. It includes a PCC temperature development model which accounts for heat generation from the hydrating paste, solar insolation, surface convection, irradiation, and dynamic specific heat and thermal conductivity values. Several mechanical properties are also modeled including thermal coefficient of expansion, drying shrinkage, creep, strength, and modulus of elasticity (using maturity methods). Finally, restraint to free movement due to slab-base friction and curling are modeled directly. These models are combined into a comprehensive software package termed HIgh PERformance PAVing (HIPERPAV).