Abstract For reliable predictions of the time-dependent behavior of concrete structures, subjected to additional loading at high ages appropriate creep models are required. A literature study on creep tests for concrete loaded at high ages revealed that only few experimental investigations on concrete creep were performed at high concrete ages. For this reason, the tests from the literature were complemented by creep tests on specimens taken from a 50-year-old concrete structure. A comparison of the experimental results from both the literature and the current experimental program with the creep strains predicted by popular creep models indicate that the latter generally underestimate the long-term creep of concrete loaded at high ages. A qualitatively correct representation of the creep deformation caused by loading at high concrete ages is provided by the B4 creep model which predicts the correct slope in the semilogarithmic representation of the compliance function for concrete loaded at high ages for both short-term and long-term creep. Hence, a promising approach seems to be an adaptation of the B4 model to reproduce the measured creep strain evolution for the particular 50-year-old structure, before it is applied in numerical simulations to support decisions on the design of rehabilitation and retrofitting measures.
Fischer et al. (Mon,) studied this question.