Abstract: The formula for calculating parameters of arctangent curve model for the autogenous volume deformation of MgO-admixed concrete is improved based on the new findings and applications of MgO-admixed concrete in recent years. The eigenvalue (ε₉₀) of the autogenous volume expansive deformation of MgO-admixed concrete at age 90 d is revised as that at age 180 d (ε₁₈₀). The autogenous volume deformation of MgO-admixed concrete calculated by the improved formula is closer to the measured value after the age of 150 d,with a deviation rate around 2%-7% or even less than 1% and the ultimate expansion reducing by 4×10^-6-7×10^-6, which is also closer to the reality.

Key words: autogenous volume deformation, arctangent curve model, parameter calculation formula, improvement, MgO-admixed concrete