Research on creep behaviour of UHPC based on experiments and viscoelastic modelling

Concrete creep is crucial to the safety of engineering structures. To address the challenge of large tonnage loading of creep on ultra-high performance concrete (UHPC), hydraulic creep instruments were used to conduct the loading tests on UHPC, which could achieve automatic load compensation for creep. The results indicated that the creep behaviors of UHPC depended on the mix proportions, the curing conditions, the mechanical properties, and even the workability. Moreover, a theoretical creep model of UHPC was proposed based on viscoelasticity theory. The model comprises rheological units that account for the properties of the fiber, the coarse aggregate, the matrix, and the interfacial transition zones (ITZs) between the fiber and the matrix and between the coarse aggregate and the matrix. The validity of the model was verified by comparing it with the creep test values and the mechanical properties of UHPC. This model had a clear physical meaning and could accurately describe the characteristics of UHPC creep.