Tensile Behavior of Concrete

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Abstract
Under tensile stress, concrete fails at low average strain but a high local strain due to nonuniform strain distribution. It is demonstrated that the use of optical interferometry with laser light both provides adequate sensitivity and allows measurement of strain over a wide field. The measurement is continuous and capable of detecting the localization of strain in zones of very small width. It is shown also that while the use of strain gages would lead to unobjective constitutive stress‐strain relations, interferometric measurement on notched specimens allows art indirect determination of the local stress‐strain and stress‐separation relations. From the knowledge of these and of the strain path in the fracture zone, the value of the fracture energy of concrete can be calculated. It is shown that the energy dissipated in the microcracked zone is a small fraction of the energy dissipated in the final separation of concrete.