Modulus of elasticity of concrete at an early age

Introduction. The assessment of the risk of early crack formation during hardening of massive monolithic reinforced concrete structures due to temperature gradients predetermines the relevance of studies aimed at increasing the reliability of methods for calculating temperature fields and stresses. When developing technological regulations for concreting, modeling methods are used to assess the risk of early crack formation, the implementation of which requires equations for changing the strength and deformation properties of concrete over time. Highly mobile and self-compacting concrete mixtures with modifiers, which are widely used in concreting the above structures, predetermine the relevance of clarifying known and identifying new patterns of change in the properties of concrete in the early period of hardening, in particular, obtaining equations for changing the E-modulus from prescription factors and temperature conditions. Purpose of the study: obtaining equations for changes in the early and subsequent periods of hardening of the E-modulus of concrete from highly mobile and self-compacting concrete mixtures depending on the prescription factors and temperature conditions during hardening. Methods. Analysis of known approaches to assessing changes in the E-modulus of concrete over time. Modeling using a three-component structural model «matrix — contact zone — aggregate.» Experimental studies of the E-modulus depending on the compressive strength limit in the early and subsequent hardening periods of concrete from highly mobile and self-compacting concrete mixtures. Results: Equations are proposed that describe the change in time of the E-modulus of concretes from highly mobile and self-compacting concrete mixtures depending on the compressive strength limit, taking into account the maturity index. The possibility of using the equation EN 1992−1-1 for the change in E-modulus from compressive strength limit for the specified concretes is shown.