Kamran M. Nemati's Research Interests

Experimental Methods in Fracture Mechanics of Concrete

The preservation of stress-induced structure and the identification of cracks induced by loading and unloading are important to understand the mechanisms for the generation, propagation and interaction of stress-induced microcracks in complex systems such as concrete. It is important to understand how the formation, growth and interaction of microcracks leads to macrofracture, which are usually the form of failure observed in engineering practice. This research aims at direct observations of the size, orientation and interaction of microcracks in concrete specimens as they exist under load.
This method involves the application of a metal in liquid phase to preserve the microstructure of stress-induced microcracks in concrete. Used in conjunction with scanning electron microscopy (SEM), it has made possible the detailed observation of microcracks in concrete as they exist under load.

Figure 1: Schematic Diagram of the Experimental Setup

The advantage of such an alloy is that it can be injected into voids and stress-induced microcracks at the desired stress level, then solidified at any stage of the experiment to preserve, in three-dimensional form, the geometry of the microcracks induced at any given stage of the experiment.

Figure 2: Typical Backscattered Electrons (BSE) images obtained from scanning electron microscope (SEM). The white areas represent the compressive stress-induced microcracks in concrete as they exist under applied stresses. line

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Send email: nemati@ce.berkeley.edu