Modeling the Effect of Curing on Early Age Distress Potential of Concrete Pavement

Understanding the early age behavior of concrete is an important issue in construction of concrete structures since different factors during construction, such as design consideration, material usage, and environmental influence, can alter the original configuration of the structure intended by the engineers and hence the structure may experience and exhibit undesired consequences. The primary interest of this research was to model the behavior of concrete under environmental excitations, such as the variation of temperature and relative humidity, during the early age after concrete placement. Experimental test results were obtained and mathematical models were developed for this research.

Modeling the effect of curing process in response to the relative humidity variation was one of the main objectives of this research. A mathematical model for back-calculating the diffusion coefficient of cured concrete from experimental test was proposed. This back-calculated diffusion coefficient of concrete was indicative of the effectiveness of curing application provided during construction. Corner deflection model for predicting lift-off displacement and climatic stress model for predicting crack formations were formulated in order to predict the distress behavior of concrete for a given design and construction scenario. Probabilistic models for lift-off displacement and cracking were formulated to predict the probabilities of such distresses. Material properties, such as strength, elastic modulus, creep, drying shrinkage, were obtained from experimental program and were used as input in these distress prediction models.

In order to assess the effectiveness of different curing compounds, two indices, such as curing index and overall curing index, were proposed. These indices were able to distinguish the difference in performance among different curing compounds. For validating the proposed corner lift-off displacement model and climatic stress model, numerical simulations were performed and the obtained results were compared with the field observations. The probabilistic models for predicting lift-off displacement and cracking behavior were validated by comparing the numerical simulation results with the field observations at Houston Intercontinental, TX. The predictions from these models were found to be in close agreement with the experimental observations. Furthermore, in order to assess the impact of a given design and construction, analytical study was performed with these models. In the sensitivity analysis, parameters of interest were the geometry of the structure, the effect of curing application, and the influence of time as well as the season of construction on the distress potentials. Numerical simulations indicated that the curing application was able to lower the early age distress potentials. The thicker slabs/overlays versus the thinner ones exhibited differences in performance in terms of distress potentials. The analytical study also revealed that it was possible to vary the distress potentials by varying the time as well as the season of construction. Finally, a constructability index was proposed in order to assist in decision making with regard to different designs and construction scenarios with a view to minimize the distress potentials in concrete structure. The results indicated that the constructability index was able to capture and demonstrate the effect of different parameters mentioned above on the constructability of rigid pavement/overlay projects.