Abstract
The modulus of elasticity of a concrete depends on the elastic stiffness of both the cementitious matrix and the aggregate–ITZ system, which includes any slippage mechanisms under loading between the aggregate and the cementitious matrix within the interfacial transition zone (ITZ). A procedure is presented in this paper to estimate the elastic stiffness of an aggregate–ITZ system within a cementitious matrix, by considering the relative volumes and the porosities of the concrete components. The method was validated by determining the elastic stiffness of both the limestone–ITZ and the electric arc furnace slag (EAFS)–ITZ systems when embedded in a slag-based cementitious matrix. The greater stiffness of the EAFS–ITZ system in comparison with the natural aggregate system explained the higher strength and modulus of elasticity of the concrete following additions of EAFS. Moreover, having determined those parameters, the elastic moduli of concretes with a similar cementitious matrix could then be accurately estimated.
Highlights
When incremental compressive loading is applied to a concrete element, concrete exhibits an elastoplastic behavior around the downward axis of the load
As the elastic stiffness of the aggregate–interfacial transition zone (ITZ) system depends on the evolution of adherence between the cementitious matrix and the aggregate within the ITZ, this elastic property will increase over time
Adopting the values obtained by Eq 10 and the coefficients in Table 3, the elastic stiffness of the electric arc furnace slag (EAFS)–ITZ system in a slag-based cementitious matrix could be considered equal to 27.1 GPa at 7 days, 33.0 GPa at 28 days, 34.3 GPa at 90 days, and 34.6 GPa at
Summary
When incremental compressive loading is applied to a concrete element, concrete exhibits an elastoplastic behavior around the downward axis of the load. A linear elastic stress–strain behavior of the concrete is observed where the strain within the concrete is directly proportional to the stress that is applied to it. When 55–60% of the compressive strength upon concrete failure is exceeded, the proportionality between the stress and the strain is progressively lost, and the material begins to exhibit a plastic behavior, characterized by the appearance of irreversible deformations in the stress–strain curve [2]. A reasonable in-service safety margin for the structural design of a given concrete structure requires that its concrete components remain within the elastic zone [4]. The modulus of elasticity is a fundamental parameter for the structural design of concrete components, the accurate estimation of which is highly relevant in this process [5]
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