Quantifying the early-age viscoelastic properties of alkali activated slag concrete using repeated minutes-long creep tests

The early-age viscoelasticity of alkali-activated slag concrete (AASC) is critical for its early-age cracking proneness and long-term performance, particularly regarding creep and internal stress development. This study employs an innovative approach to quantify the early-age viscoelastic behavior of AASC, utilizing a Temperature Stress Testing Machine to conduct compressive, repeated and minutes-long creep tests, covering the curing age from 6 h till 28 days. This study is based on the linear theory of viscoelasticity and the Boltzmann superposition principle. A double power law function is employed to model creep and to further predict the internal stress of restrained AASC. It is demonstrated that the double power law function accurately captures the short-term creep of AASC, enabling reliable predictions of early-age stress accumulation and relaxation. Overall, this study highlights the pronounced viscoelasticity of AASC and the effectiveness of the experimental and modelling approaches used to quantify it.