Estimation of the modulus of elasticity for sprayed concrete

• Elastic modulus prediction performed with current equations overestimates the value.
• Adaptation of the Eurocode 2 and EHE-08 equations entails better results.
• Empirical and semi-analytical formulations are proposed.
• Modified equations are validated with results obtained in real tunnels.

The modulus of elasticity is a fundamental parameter for the structural design. It has been studied in the literature and several standards include equations to predict its value for conventional concrete. However, the same is not true in the case of sprayed concrete. This special concrete presents singular characteristics due to the spraying process that must be considered in the prediction of this property. The objective of the present work is to perform an analysis of the modulus of elasticity of sprayed concrete. For that, an experimental program about the mechanical properties of the material was executed. Furthermore, the applicability of formulations available in current codes and guidelines to estimate the modulus of elasticity of conventional concrete is assessed. The analysis conducted provides the basis to adapt these formulations, taking into account the specificities of sprayed concrete. Finally, empirical and semi-analytical expressions are proposed and validated using data from real tunnels.