Calculation of shrinkage stress in concrete structures with impact of internal curing

摘要

This paper presents recent advances in the calculation of shrinkage stress in concrete structures, especially focus on the effect of internal curing. In the modeling, an integrative model for autogenous and drying shrinkage predictions of concrete under drying environments is introduced first. Second, a model taking both cement hydration and moisture diffusion into account synchronously is used to calculate the distribution of internal relative humidity in concrete. Using the above two models, along with the shrinkage stress model for concrete pavement under nonlinear strain along the slab thickness, the development of shrinkage stress in concrete pavements since casting made by low, middle and high strength concrete respectively is calculated. In particular, the effects of internal curing with pre-wetted lightweight aggregates on the progress of shrinkage stress are investigated and discussed. Based on the present study, the following conclusions can be drawn: (1) the progress of shrinkage stress in concrete pavements obeys two-stage mode since concrete casting, a small stress stage (close to zero) in the moisture saturated period and a gradual increasing stage with the relative humidity gradually decreasing in the concrete; (2) the closer to the drying face, the higher the shrinkage stresses; (3) the shrinkage stress is greater in high strength slab than that in low or middle strength slab; (4) internal curing with pre-wetted lightweight aggregate can greatly reduce shrinkage stress in concrete pavement, either in low strength slab or high strength slab.