9713997 Perdikaris The influence of the microscale and concrete compressive strength on the fracture energy per unit crack surface area will be evaluated by studying the roughness characteristics of a fracture surface, such as the surface roughness index, fractal dimension and wavelength content. The major objectives of this research are: a) to perform 3-point bending tests under CMOD control on concrete beam specimens of three sizes with three maximum aggregate sizes and three concrete compressive strengths and determine the roughness characteristics of the fracture surfaces, that is the roughness index, fractal dimension, and Fourier amplitude spectra for each fracture surface b) to study the roughness characteristics of the fracture surfaces and to evaluate their dependence on the maximum aggregate size and concrete compressive strength and their influence on the "load vs. load-point-displacement" response and the specific fracture energy. c) to develop a micromechanics-based semi-empirical analysis, wherein the apparent toughness will be calculated based on the given roughness characteristics of the observed crack paths and aggregate size. This research program will be undertaken through a university- state-industry collaboration. The results will improve the methods of specification and evaluation of the performance of normal and high strength concrete resulting in more efficient designs.
