UC, Berkeley


Comparative Study of High-Strength Concrete Fracture Under Uniaxial and Triaxial Loading


K. M. Nemati and P. J. M. Monteiro

Department of Civil Engineering
Division of Structural Engineering, Mechanics and Materials
University of California at Berkeley
Berkeley, California 94720, U.S.A.


Cylindrical specimens of high-strength (76 MPa) concrete were tested under compressive uniaxial and triaxial loading conditions. The resulting induced cracks were impregnated by a metal alloy which liquefies at higher temperatures (70-85C) but is solid at normal temperatures. This testing method allows the preservation and identification of cracks and pores in concrete as they exist under load. The specimens were then observed using scanning electron microscopy (SEM). The backscatter electron images obtained from the SEM were analyzed by computerized image analysis technique to determine the effect of different loading conditions on the crack behavior of high-strength concrete. Detailed analysis of the SEM images obtained from the high-strength concrete samples after crack induction revealed the profound effect of triaxiality as opposed to uniaxial testing on crack orientation, crack density, crack length, crack branching, as well as the interfacial cracks between the matrix cement paste and the aggregate.


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