Moisture profiles and shrinkage in early-age concrete pavements

This paper describes the effort placed to apply a series of discrete test and analysis methods as an integrated approach for the estimation of time- and position-dependent humidity changes and shrinkage in early-age concrete. The total moisture loss in concrete is assumed to be a result of autogenous drying and conventional external drying. Autogenous drying or self-desiccation is expressed as a function of the degree of hydration in terms of strength ratio, which can be determined by the maturity and strength relationship. Moisture loss due to external drying is estimated by finite element analysis based on the nonlinear diffusion theory. Estimated humidity reduction is then used to estimate shrinkage potential in the concrete by applying a linear shrinkage coefficient, which may be determined by tests. Time- and position-dependent shrinkage potential will be useful for further stress analysis. Application of the analysis approach is introduced with an example analysis for a 300 mm × 300 mm cylinder specimen tested under 1D drying for the first 7 days since after casting.