Synopsis
A method developed earlier for estimating long-term creep and shrinkage from short-term measured test data is shown to be satisfactory for predicting ten-year values. For water-stored concrete, swelling at ten years is appreciable, and therefore the method is extended to predict long-term swelling. Using thirty-year strain (extrapolated from experimentally determined ten-year strain), five standard methods of prediction are compared in performance. When applied in their basic form, all methods are unsatisfactory and it is recommended that, depending on the required accuracy, the secant modulus of elasticity be determined and used with the Concrete Society/Cement and Concrete Association method to predict thirty-year strain. For improved accuracy, short-term test data are necessary for use with either the author's method or the Bažant and Panula model II method.
