Instantaneous and short-term deformation of early-age concrete under quasi-instantaneous loading

Abstract

In order to assess accurately the stresses in early-age concrete, a realistic compliance function is required. The existing compliance functions, however, have been deduced from the data of hardened concrete and thus the rapid change during the hardening process in early-age concrete cannot be considered rationally. The purpose of this study is to propose a compliance function that can describe the highly viscoelastic behaviour in very early-age concrete. A test method to estimate the instantaneous compliance without creep effect was investigated first and tests were performed to determine the instantaneous and creep compliance. While both material parameters relating to instantaneous and ageing viscoelastic compliance were constants in the existing model based on the solidification theory, the test results showed that they had a strong age dependency at very early ages. A modified compliance function was proposed to provide more realistic prediction of the behaviour of early-age concrete.