Experimental assessment and modelling of effective tensile elastic modulus in high performance concrete at early age

This paper focuses on the age-adjusted effective elastic modulus (E-a (t,t(0))) in high performance concrete subjected to sustained tensile loading conditions at early age. First, the existing approaches to determining E-a (t,t(0)) are discussed, underlining their limitations. Second, a novel experimental approach is put forward to capture E-a (t,t(0)) using an advanced Temperature Stress Testing Machine and a unique direct tensile test setup. In this approach, both pure elastic modulus (E(t)) and E-a (t,t(0)) can be directly measured, whereas, in existing methods, the predictions are based on empirically determined values/models of ageing and creep coefficients. A unique set of test data obtained based on the proposed approach is presented to assess the early-age evolution of E-a (t,t(0)) and its key influencing factors. Such obtained experimental values are used to compute the evolutions of the reduction factors (k(t,t(0))) simply by obtaining the ratio between experimentally determined values of E(t) and E-a (t, t(0)). The applicability of existing approaches for predicting k(t,t(0)) is evaluated, and the causes for discrepancies between experimental values and predictions are discussed. Finally, an empirical model is proposed in this paper to quantify the k(t,t(0)) profiles. It is shown that the proposed model is convenient, easily adaptable for different types of concrete without the need for an extensive test database, and yet realistically reflects the nonlinearity of k(t,t(0)) profiles at early ages.

Automated summary

This paper focuses on the age-adjusted effective elastic modulus in high performance concrete under sustained tensile loading conditions at early age. A novel experimental approach is proposed to capture the evolution of this modulus, and an empirical model is suggested to quantify the reduction factors profiles. The proposed approach offers a convenient and adaptable method for assessing early-age concrete behavior.