Tensile Creep Tests of Hydraulic Concrete under Different Curing Conditions

Abstract

Concrete creep is related to not only loading age and holding time but also curing temperature and humidity. To investigate the influences of curing temperature and humidity on creep performance, tensile creep tests of hydraulic concrete were conducted under different curing conditions (wrapped, exposed, and water). First, based on the measured strains in the compensation specimens, strain statistical models were established to separate the thermal strain, autogenous volume strain, dry shrinkage strain, and wet expansion strain under different curing conditions. Then, the measured strains in the loaded specimens and compensation specimens were investigated. Analogous to the dry shrinkage strain and drying creep, the concept of wet expansion creep, which corresponds to the wet expansion strain, was proposed. Hence, the total creep strain, basic creep strain, drying creep strain, and wet expansion creep strain results were obtained under different curing conditions. Finally, based on the equivalent-age theory, a fractional-order creep model that considers the coupling effects of temperature and humidity was proposed for hydraulic concrete, and the parameters of the new model were determined using the tensile creep test data and a complex optimization method. The results show that the fractional-order creep model can describe the growth rule of the tensile creep of concrete under different curing conditions.