Knowledge of the tensile Youngââ?¬â?¢s modulus of concrete at early ages is important for estimating the risk of cracking due to restrained\r\nshrinkage and thermal contraction. However, most often, the tensile modulus is considered equal to the compressive modulus and\r\nis estimated empirically based on the measurements of compressive strength. To evaluate the validity of this approach, the tensile\r\nYoungââ?¬â?¢s moduli of 6 concrete and mortar mixtures are measured using a direct tension test. The results show that the tensile\r\nmoduli are approximately 1.0ââ?¬â??1.3-times larger than the compressive moduli within the materialââ?¬â?¢s first week of age. To enable\r\na direct estimation of the tensile modulus of concrete, a simple three-phase composite model is developed based on random\r\ndistributions of coarse aggregate, mortar, and air void phases. The model predictions show good agreement with experimental\r\nmeasurements of tensile modulus at early age.
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