Effect of Crack Growth on the Overall Mechanical Properties of Cement Composites


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Title: Effect of Crack Growth on the Overall Mechanical Properties of Cement Composites

Author(s): Momahed Boulfiza and Nemkumar Banthia

Publication: Special Publication

Volume: 224


Appears on pages(s): 193-206

Keywords: fibers, reinforced concrete, thin sheet CFRC, overall behavior, homogenization, damage

Date: 12/1/2004

Cement-based composites, reinforced with randomly distributed short fibers exhibit a nonlinear behavior, called damage, which could be described in terms of microcrack initiation, growth and coalescence leading to the creation of macrocracks. A micromechanics-based continuum damage mechanics, MBCDM, model is proposed for the prediction of the effect of initial microcrack configuration and propagation on the macroscopic Young’s modulus and thermodynamic force associated with the chosen damage variable. Parametric studies for a number of periodic crack distributions in a two-dimensional case have been carried out. Both unreinforced (brittle) and pitch-based carbon fiber reinforced thin sheet cementitious materials have been considered. It is shown that despite the relative simplicity of the damage measure used, the model was able to capture the main effects of cracking patterns on the overall behavior of the composite. Simulation results also reveal that, whereas the evolution of the normalized stiffness is practically the same for all configurations over the entire range of damage variation, the damage thermodynamic force is different for each case. The results predicted by the proposed approach, appear to be consistent with experimental observations regarding the tensile behavior of CFRC composites.