Experimental values of early-age tensile strength/strain capacity are relatively scarce in literature due to practical difficulties in performing direct tensile testing during setting and early hardening stages. Existing methods do not allow determining the tensile strain capacity from fresh state…
Experimental values of early-age tensile strength/strain capacity are relatively scarce in literature due to practical difficulties in performing direct tensile testing during setting and early hardening stages. Existing methods do not allow determining the tensile strain capacity from fresh state to hardening stage. A new experimental procedure has been designed to provide a continuous evolution of tensile strength and tensile strain capacity of concrete from fresh state to the age of 24 hours. The measure of displacements was deduced from digital image correlation. The output data allow determining stress–strain curves and tensile strain capacity. This is defined as the strain when the main crack appears. The parameters of the study were the water-to-cement ratio, the paste volume, and the type of coarse aggregates. The evolution of the tensile strain capacity showed a minimum between final setting time and early hardening stage. This age actually corresponds to a critical period for early-age cracking risk. The elastic modulus actually increased from very early ages whereas tensile strength did not show significant development before final setting. This shift between the developments of both properties implied a minimum for the evolution of tensile strain capacity. The coarse aggregate type had a limited influence on tensile behavior. The water-to- cement ratio and the paste volume had a significant effect, which could be taken into account for early-age cracking control.