The purpose of this study is to investigate plastic cracking in early age concrete. Experiments were performed to investigate, at early ages, the fracture energy and tensile strength of the concrete. The critical mouth opening displacement, characteristic length and tension softening curve based on the concepts of the Hillerborg’s cohesive crack model were also investigated. Obtain data corresponding to work of previous 2005 thesis project, Abel (1998) and Karihaloo (1995).
A tensile strength test using an Instron machine was performed on each specimen. The specimens consisted of 32MPa and 50MPa concretes with different mix design. The tests were carried out from as early as two hours up to six hours after batching. Load-displacement curves of average of specimens were obtained and subsequently evaluated using linear elastic fracture mechanics.
The results from the experiments and analysis showed that the fracture energy and tensile strength increase with time, while the deformation at failure decreases as the concrete matures. Finally, the ductility of the specimens were investigated and compared.