The study presented research on the possibility of using acoustic emission to detect and analyze the development of the alkali-silica reaction (ASR) in cement mortars. The experiment was conducted under laboratory conditions using mortars with reactive opal aggregate, accelerating the reaction by ensuring high humidity and temperature, in accordance with ASTM C227. The progress of corrosion processes was monitored continuously for 14 days. The tests were complemented with measurements of the expansion of the mortars and observations of microstructures under a scanning electron microscope. The high sensitivity of the acoustic emission method applied to material fracture caused by ASR enabled the detection of corrosion processes already on the first day of the test, much sooner than the first recorded changes in linear elongation of the specimens. Characteristic signal descriptors were analyzed to determine the progress of corrosion processes and indicate the source of the cracks. Analysis of recorded 13 AE parameters (counts total, counts to peak, duration, rise time, energy, signal strength, amplitude, RMS, ASL, relative energy, average frequency, initial frequency and reverberation frequency) indicates that the number of counts, signal strength and average frequency provide most information about the deleterious processes that occur in the reactive aggregate mortars. The values of RA (rise time/amplitude) and AF (average frequency) enabled the classification of detected signals as indicating tensile or shear cracks. The acoustic emission method was found suitable for monitoring the course of alkali-aggregate reaction effects.
The article presents the project and realization of Ivigna (in Merano, Italy) aerial cable car project designed by architect Roland Baldi. The boxed form has been boldly and confidently introduced into the surrounding mountains, despite distancing itself from standard references to genius loci of the natural landscape. This project presents an avant-garde, innovative and reliable approach to the composition of architecture in the context of a mountain landscape. Despite the severity of forms, a kind of architectural rhythm and lightness of shaping the object introduced in the context of an open space can be sense here. It is essential to seek new forms and technologies for communing with nature and culture, in order to shape interesting modernist architecture, entering the twenty-first century.