ACOUSTIC-EMISSION IN FIBER-REINFORCED CONCRETE

This investigation is aimed at diagnostic studies on the behavior at d ifferent interfaces in fiber reinforced concrete: between hardened cem ent paste and sand, between mortar and coarse aggregate and between co ncrete and fibers. Other types of internal failure include aggregate c rushing, fiber rupture, and so on. Only cylindrical specimens, with va rying volume percentage and aspect ratio of fibers, have been tested i n compression. For quite some time additives like latexes, plasticizer s, fibers and silica fume are incorporated in concrete and mortar to i mprove one quality or the other of concrete, but one single common obj ective is delaying or arresting interface cracks. This investigation a ttempts to relate external behavior to internal signals of distress th rough acoustic emission. This helps to identify critical internal dist ress vis-a-vis external level of stress. Further, spectral analysis of acoustic signals has been attempted in frequency domain in order to e stablish which types of interface failure are predominant at different stages of stress. Such understanding could enable material scientists to decide on the parameters of additives with greater confidence when developing composites with desired external response. Of interest are instrumentation and on-line data processing in order to record (a) cu mulative acoustic activity and (b) spectral analysis in frequency doma in at different stages of progressive loading.