• Lura, Pietro
• Li, Liang
• Dabarera, Arosha
• Dao, Vinh

Abstract

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.

Topics

• impedance spectroscopy
• aging
• creep