## 2 Materials and Methods
### Abrasion in Los Angeles Machine  
The Los Angeles abrasion test is a test for the determination of mineral aggregate degradation resulting from a combination of impact and abrasion. Material testing in the Los Angeles machine is standardised and described in (1) ASTM C535-16 \"Resistance to Degradation of Large-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine\" [29], (2) ASTM C131/C131M-14 \"Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine\" [30], and (3) BS EN 1097-2:2010 \"Tests for Mechanical and Physical Properties of Aggregates, Part 2: Methods for the Determination of Resistance to Fragmentation\" [31]. We applied the modified test procedure for abrasion tests in the Los Angeles machine. Three samples of particle mixtures (for three test repetitions), of the same grade as the particles abraded in the micro-Deval, were selected. Each sample weighed about 2.0 kg in total. Particles were subjected to abrasion in the Los Angeles machine in a dry condition and without the presence of steel balls so that the material did not crush too fast, which allowed us to track its morphological changes more precisely. Without the steel balls, the material only abrades itself. The Los Angeles machine used in the experiments was a standard machine (MATEST A075N) (Figure 3). The drum filling was 0.35% for the first cycle. Five consecutive cycles of abrasion were carried out on each sample. Cumulatively, particles were subjected to 1500 rotations (about 47 min in total). Durations of individual cycles at the rotational speed of 31-33 rpm were (in order): 160, 160, 180, 500, and 500 rotations (\(\approx\)5, 5, 5, 15, 15 min). After each cycle, the material coarser than 4.0 mm was manually sieved (using 63, 50, 45, 40, 37.5, 31.5, 25, 20, 16, 14, 12.5, 10, 8, 6.3, and 4 mm sieves) to minimise any additional clipping and loss of material. The portion of the material finer than the 4.0 mm sieve was sieved in an electromagnetic sieve shaker (Haver and Boecker EML 450 digital plus) using 2.0, 1.7, 1.6, 1.0, 0.63, and 0.063 mm sieves. Material passing through the 0.63 mm sieve was considered as the mass loss of the mixture. The sieve size of 0.63 mm (630 \(\upmu\)m) represents the coarse sand lower boundary sieve size [32]. This size was selected because sediment particles in the range between 0.63 and 0.063 mm can often be found in a suspended load along the -0.063 fraction [33; 34]. Additionally, when dry sieving such fine fractions, a considerable portion of undersized particles tends to stay on the upper sieve. After the sieving, it could be seen that the mesh of the 0.063 mm sieve sometimes got clogged (almost cemented) so that finer particles could not pass through. The other factor preventing a complete passing of the finer particles was that due to vibrations of the sieve shaker, the smallest particles floated in a similar manner as when the drum lid is opened. It should also be mentioned that a small portion of the material was lost in the form of dust when opening the drum cover after an abrasion cycle, through clogging inside of the mill between the lifter and the curved surface, during the sample handling, etc. Material coarser than a 20 mm sieve was  
Figure 2: Micro-Deval apparatus.  
analysed in the dynamic image analyser. Smaller particles' shapes were not analysed due to the high possibility of material getting lost during the analysis.