## 3 Results and Discussion
### Morphology  
During the low-energy abrasion, particles' form evolution was much slower, and they were, in general, preserved. Particles abraded at the lower energy levels mainly preserved the initial shape class during the whole abrasion applied to them. This can be seen in Figure 12a, which presents particles abraded in the micro-Deval apparatus in their initial form (marked with squares) and after 15 abrasion cycles (marked with circles). Other studies investigating shape (form) evolution according to [PERSON]'s classification described similar observations [46; 50; 52]. On the other hand, during the higher energy abrasion, form evolution happened fast. Particles dispersed on Zingg's diagram after each abrasion cycle regardless of their previous form (shape class) due to breakage and the creation of new particles (Figure 12b). After the fifth cycle, many particles (coarser than 20 mm) migrated towards the equant end member of the classification (53.85%) if compared to the initial phase (33.33% equant particles) and after the first cycle (29.63% equant particles). Following the equant end member in the count was the prolate end member (26.92% after the fifth cycle). Figure 12b shows particles from one of the mixtures abraded in the Los Angeles machine (LA1) in their initial form (marked with squares), after one abrasion cycle (marked with Xs), and after five abrasion cycles (marked with circles). The form changes can also be seen in the pictures of the material abraded in the experiment (Figure 13). Regarding the roundness and angularity aspect of the particle shape, it experienced the biggest relative (percentual) change during both of the experimental setups. Therefore, we  
Figure 12: Particle form classification according to [PERSON] [5]. (**a**) Particles’ form before testing in micro-Deval apparatus (marked with squares) and after 15 cycles of abrasion in micro-Deval apparatus (marked with circles) A square and a circle of the same colour represent the same particle. (**b**) Particles’ form before testing in Los Angeles machine (marked with squares), after first cycle of abrasion (marked with Xs), and after fifth cycle of abrasion in Los Angeles machine (marked with circles). Figure 13: Particles from the abrasion tests. Particles from tests in Los Angeles machine (at initial state, after first cycle, and after fifth cycle) in the first row. Particle from tests in micro-Deval apparatus (at initial state, after fifth cycle, and after fifteenth cycle) in the second row. can argue that the biggest change occurs in the aspect of rounding of material. With respect to mass loss, during the more energy-intensive abrasion process, particles experienced a slightly higher change in sphericity and convexity, whereas angularity experienced a higher relative change during the low-energy abrasion. On the other hand, with respect to total introduced energy, particles experienced considerably higher shape changes during more energy-intensive abrasion in the sphericity and convexity parameters, whereas angularity showed a similar change for both low-energy and high-energy abrasion. This can be attributed to the breakage that occurs during the high-energy abrasion, which results in the propagation of sharp edges and diminution of rounding. All of the relative (percentual) changes with respect to mass loss (Figures 14-16) show a similar trend, but with respect to the total energy (work), high-energy abrasion shows a much higher change in sphericity and convexity, with a steeper slope. The absolute value of the convexity parameter (surface texture aspect of particle shape) is higher for the low-energy abrasion at the same mass loss values, implying that a particle becomes smoother faster if abraded slower. A similar aggregate behaviour was observed by [PERSON] and [PERSON] [54], where surface-texture-wise tested aggregates kept an unchanged texture after the Los Angeles (standard) test, but the surface became significantly smoother after the micro-Deval (standard) test.