ACOUSTIC EMISSION ACTIVITY IN DUCTILE FIBER REINFORCED CEMENTITIOUS COMPOSITES

摘要

This study was performed in the framework of a research program focused in the development of high tenacity polypropylene (PP) fibres for the reinforcement of cementitious composites. Precedent reports have demonstrated how micromechanical modelling was used to attain significant improvements with respect to the macroscopic properties of cementitious composites. These improvements have been based on the optimized composition of the sheath of bi-component core/sheath fibers that resulted in a better interfacial frictional and chemical bonding of the fibers with the cement matrix. The principal aim of this study has been to evaluate the characteristics of AE data and correlate them with the particular fiber reinforcement. The analysis has led to the observation of clear distinct behaviour for each of the different types of fibers. Those types were namely polypropylene with variant surface coatings and polyvinyl alcohol (PVA) fibres. The results of the 'source location' data were compared to visually observed cracks during runtime with a microscope, so as to verify the supposed cracking behavior uniformity of the PP fiber composites in contrast to the localized cracking of the PVA composites. Statistical measures as the number of events and the accumulated energy of the recorded signals were to allow one to infer the underlying reinforcement.