2022 Volume 76 Issue 1 Pages 153-161
In this study, mass changes and length changes were measured using ordinary Portland cement and low heat Portland cement to investigate drying shrinkage properties in hardened low heat Portland cement. The mass change-length change relationship can be approximated by two straight lines, with the changing point of slope corresponding to about 50％ RH. From the change in the slope of the mass change-length change relationship, it can be inferred that only reversible drying shrinkage occurs in the low humidity range, while irreversible drying shrinkage occurs in addition to the reversible one in the high humidity range. The irreversible drying shrinkage of L is large, which we attribute to the larger amount of C-S-H per unit volume and smaller gel-space ratio which is deduced from the difference in Nitrogen sorption and portlandite amount. The C-S-H formed in L cement has larger interlayer space and at a more uniform state. Hence it is easier to make crosslinking between layers upon drying, resulting in higher irreversible shrinkage.
