Tensile basic creep: Measurements and behavior at early age

Creep and shrinkage of concrete under sealed and wet curing conditions have been investigated to determine the tensile basic creep of concrete during the first days after casting. The common practice of sealing concrete to measure basic creep was found inaccurate because internal drying at this age is generally a significant factor. Instead, a moist cover was placed on the concrete samples to successfully suppress early-age shrinkage. A basic creep model based on solidification theory was implemented to provide insight on the behavior of plain and fiber-reinforced concrete. The results revealed a high rate of basic tensile creep during the first 20 h of loading, which decreased afterward and approached a bound limit. More importantly, the tensile basic creep was found sensitive to age at loading only within the first few days and age-independent after 5 to 6 days. Finally, steel fiber reinforcement lowered the initial rate of tensile basic creep.