When understanding the effect of the morphology of coarse aggregate on the properties of a fresh concrete mixture, the strength and deformability of self-compacting high-performance fibre-reinforced concrete (SCHPFRC) can be seen to be critical for its performance. In this research, regular and irregular grains were separated from granite coarse aggregate. The morphology of these grains was described while using digital image analysis. As a result, the aspect ratio, roundness and area ratio were determined in order to better understand this phenomenon. Then, the principal rheological, physical, and mechanical properties of SCHPFRC were determined. The obtained results indicated that the morphology of the grains of coarse aggregate has an impact on the strength and stiffness properties of SCHPFRC. Moreover, significant differences in the transverse strain of concretes were observed. The morphology of the coarse aggregate also has an impact on the rheological parameters of a fresh concrete mixture. To better understand this phenomenon, the hypothesized mechanism of the formation of SCHPFRC caused by different morphology of coarse aggregate was proposed at the end of the article.

The aim of the article was to verify the possibility of using open source digital image analysis software to determine the particle shape. Devices using laser diffraction or dynamic image analysis could be used to determine size and shape of particles. However, the laboratory devices for digital image analysis are relatively expensive. For this reason, it was decided to use open source digital image analysis software Fiji Is just ImageJ and mobile phone with a 12 Mpx camera. Coarse aggregates of basalt and granite were used in the study. Flakiness index (FI) and shape index (SI) were determined using two methods: in accordance with the European Standard and with the use of digital image analysis (reference method). Based on the obtained results it was found that there is an appropriate relationship between the European Standard method and the reference method.

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences

The aim of this this paper was to investigate the effectiveness of flotation process depending on the changeable dose of reagents and variable speed of rotor in flotation device. HPGR crushing products were used as a feed in all flotation tests. Efficiency indices, along with Fuerstenau curves, were determined for each test. Both rotational speed and the dose of reagent have affected the flotation results in a lower degree that expected. However it could be possible to determine the optimal dose and rotational speed of rotor that increase the effectiveness of flotation process.