A numerical model for predicting the drying shrinkage behavior of concrete under ultra-low relative humidity

Abstract

The drying shrinkage caused by rapid water loss will pose a great threat to the safety of concrete structures, especially for those serviced in an extremely dry environment. However, the majority of reported research primarily focuses on drying shrinkage behavior of concrete under relative humidity (RH) ranging from 50% to 100%, and the corresponding drying shrinkage prediction models have poor applicability, leading to an unclear understanding of it under ultra-low RH (RH<40%). In this study, a numerical model, finite element model with cohesive elements, was proposed to better predict the drying shrinkage behavior of concrete, even under the RH of 20%. Initially, geometric models of concrete with varying coarse aggregate size ranges and volume fractions were established. Subsequently, based on the relationship between RH and humidity diffusion coefficient of concrete with different water-cement ratio (w/c), a drying shrinkage model was proposed to examine the corresponding shrinkage strain of concrete even under ultra-low RH conditions, and its validity was verified through comparison with reported experimental research. Utilizing the developed model, the effects of size range and volume fraction of coarse aggregate, and the w/c, on the drying shrinkage of concrete across a wide range of RH levels were systematically investigated. The results indicated that increasing the aggregate size range can only slightly inhibit drying shrinkage, while there is a marked inhibition effect on it (decrease by about 45% at most) for increasing the aggregate vol% or reducing w/c, even under ultra-low RH of 20%. Finally, grey relation analysis was employed to assess the inhibition weight of each parameter on the drying shrinkage, following this sequence in order: RH > w/c > coarse aggregate vol% > coarse aggregate range size. We also envision that the proposed model could provide feasible guidelines for the inhibition of concrete in ultra-dry regions.