Application of a poromechanistic-empirical drying shrinkage modeling approach to structural design of concrete pavements

Abstract

Top-down drying in concrete pavement slabs causes differential drying shrinkage strains ($\varepsilon_{sh}$), which may warp the slab and lead to cracking. Warping is typically represented by an equivalent temperature difference ($ETD_{sh}$) that will cause the same slab curvature as $\varepsilon_{sh}$. However, the current $ETD_{sh}$ computation procedures are empirical and simplified. In this study, a poromechanistic-empirical (PME) procedure is proposed to compute time-dependent $ETD_{sh}$ for concrete pavements. The PME procedure integrates a diffusion model to predict the internal relative humidity with a poromechanistic model to calculate $\varepsilon_{sh}$-profiles. Both models are calibrated based on differential drying experiments conducted on mortar prims from seven mixture designs. After applying an empirical correction for coarse aggregate volume, the developed $\varepsilon_{sh}$-profiles are used to calculate $ETD_{sh}$ for an instrumented pavement section in Pennsylvania for validation. Higher sensitivity of the PME procedure compared to the current pavement design guide, AASHTOWare PavementME, to both mixture design and climate is demonstrated for four pavement sections. The largest difference in $ETD_{sh}$ among the climates is 33$^\circ$C based on the PME procedure, as opposed to only 2$^\circ$C by PavementME. PME $ETD_{sh}$ also shows the benefits of fly ash and low w/cm to mitigate warping, especially in dry non-freeze climates.