Early Age Deformation and Resultant Induced Stress in Expansive High Strength Concrete

Abstract

Expansive additive is well known to be effective in compensating early-age shrinkage and the resultant induced stress in reinforced high-strength concrete (HSC) members. On the other hand, there have been few studies on numerical analysis methods for evaluating such early-age induced stress, which are vital to verify the risk of cracking. The present study formulates a 3-dimensional finite element method as well as a practical calculation method based on the beam theory, both of which consider the principle of superposition and linear stress-strain relationship of creep, in order to evaluate the early-age shrinkage/expansion-induced stress in reinforced members. The applicability of the proposed methods is evaluated by comparing computed values with experimental values on shrinkage/expansion-induced stress in RC beam specimens composed of various HSCs, using expansive additive and/or shrinkage reducing chemical agent and/or low-heat Portland cement. The results demonstrate that the proposed finite element method can accurately simulate induced stress in the reinforced concrete beams, even when expansive additive is used, and this indicates that the linear stress-strain relationship may be valid for expansive high strength concrete. Furthermore, there is a good agreement between the finite element method and a practical calculation method based on the beam theory, even in the case of RC beams with stirrups that cause a three-dimensional restraint condition in concrete.