Influence of Loading Ages on the Early Age Tensile Creep of High-Strength Concrete Modified with Superabsorbent Polymers

This research investigated tensile creep of early age high-strength concrete (HSC) modified with superabsorbent polymer (SAP). A temperature stress test machine was utilized to investigate the influence of loading age (0.50, 0.67, 0.83, 1, 3, 5, and 7 days) on the tensile creep performance of HSC modified with SAP at early age. The experimental analyses indicated that (1) the basic tensile creep, basic tensile creep coefficient, and specific basic tensile creep of HSC modified with SAP decreased with increasing loading age, and the aging effect on the tensile creep of HSC modified with SAP was significant when the concrete was loaded within 1 day; (2) the specific basic tensile creep rate was high at early loading ages, then decreased and tended to be stable, and the earlier the loading age, the greater was the divergence between the initial creep rate and the later creep rate at the same loading age; and (3) the relative specific basic tensile creep decreased exponentially when concrete was loaded within 1 day and decreased linearly when concrete was loaded after 3 days, and the proportionality limit of specific basic tensile creep occurred at a loading age of 1.60 days, which was determined by linear and nonlinear regression analysis. A model for predicting the tensile creep of HSC modified with SAP considering loading age is proposed.