Design provisions for drying shrinkage and creep of normal-strength concrete

This paper presents a design-office procedure for calculating the shrinkage and creep of concrete using the information available at design, namely, the 28-day specified concrete strength, the concrete strength at loading, element size, and the relative humidity. The method includes strength development with age, relationship. between modulus of elasticity and strength, and equations for predicting shrinkage and creep. The method can be used regardless of what chemical admixtures or mineral by-products are in the concrete, the casting temperature, or the curing regime. The only arbitrary information are factors appropriate to the cementitious materials which can be improved from measured strength-age data. At the most basic level, the proposed method requires only the information available to the design engineer The predicted values can be improved by simply measuring concrete strength development with time and modulus of elasticity. Aggregate stiffness is taken into account by using the average of the measured cylinder strength and that back-calculated from the measured modulus of elasticity of the concrete. The predictions are compared with experimental results for 185 data sets for compliance and 115 data sets for shrinkage. The comparisons indicate that shrinkage and creep can be calculated within +/- 30%. Comparisons with the same experimental data are presented for ACI 209, CEB MCI990 and B3.