Practical formulation of shrinkage and creep of concrete

A set of algebraic formulas is proposed to describe the shrinkage and creep of concrete over the entire range of time durations of interest. The formulas cover: the effects of drying at various environmental relatire humidities, the size and shape of cross section, aging (due to hydration), the effect of time lag of loading after the start of drying, creep of specimens predried to various humidities, the nonlinear dependence of stress, the increase of nonlinearity at simultaneous drying, and the decrease of strength for long-time loads. Simplification in the form of a linear dependence on stress is obtained as special case. The formulation is an extension of the double power creep law, which has been recently proposed for creep in absence of moisture exchange. The shape of the time curves of creep depends on the humidity. A rather close agreement with the extensive experimental data available in the literature is demonstrated.