9522984 Landis This is a joint research project between the University of Maine and Northwestern University. The objective of the research is to observe the three dimensional growth of internal microcracks in small cement and mortar specimens loaded in uniaxial compression. The microcracking will be measured using synchrotron x-ray microtomography combined with a 3-D image analysis technique. The research work represents the first time that quantitative measurements of internal cracking of cement-based materials have been possible at micron resolution. A clearer understanding of fracture mechanisms are critical for the development of materials which are both stronger and tougher. Recently, using the concepts of microfine particle packing in the range of submicron millimeter, concrete with a compressive strength of up to 800 Mpa has been developed. The influence of particle size distribution (reactive and non-reactive particles) on fracture toughness is to be investigated.