Several methods, including X-ray radiography, have been developed for the investigation of the characteristics of water-saturated quasi-brittle materials. Here, the water content is one of the most important factors influencing their strength and fracture properties, in particular, as regards to porous building materials. However, the research concentrated on the three-dimensional fracture propagation characteristics is still significantly limited due to the problems encountered with the instrumentation requirements and the size effect. In this paper, we study the influence of the water content in a natural quasi-brittle material on its mechanical characteristics and fracture development during in-situ four-point bending by employing high-resolution X-ray differential micro-tomography. The cylindrical samples with a chevron notch were loaded using an in-house designed four-point bending loading device with the vertical orientation of the sample. The in-house designed modular micro-CT scanner was used for the visualisation of the specimen’s behaviour during the loading experiments. Several tomographic scans were performed throughout the force-displacement diagrams of the samples. The reconstructed 3D images were processed using an in-house developed differential tomography and digital volume correlation algorithms. The apparent reduction in the ultimate strength was observed due to the moisture content. The crack growth process in the water-saturated specimens was identified to be different in comparison with the dry specimens.
This paper presents the possible solutions of daily circulations in terms of the transport ensuring the daily performance of vehicles and staffing. It is focused on the determination of these vehicles as the daily circulation optimal variant as well. It appears that the analysis of the transport solution is the first step to determine the successful optimal solution of the transport performance volume. Subsequently, the transport solution must be tested from an economic point of view.
The role of practical work in the training of student teachers is central to the development of their future pedagogy and practice. However, not all laboratory based activities give sufficient challenge in the development of both cognitive and practical skills. The activity proposed in this paper helps reinforce an understanding of reaction kinetics through a study of the reaction of zinc with sulfuric acid. In this study, the observed reaction kinetics conflicted with the typical expectation, which offered a problem to motivate an inquirybased activity.
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