# Effect of Metallic Waste Addition on the Physical and Mechanical Properties of Cement-Based Mortars
## 3 Results and Discussion  
### Analysis of the Morphology and Composition of Metallic Waste  
Figure 3 shows the morphological properties of steel shavings and steel wool fibres before the mixing process, adjusted to a Weibull probability distribution function, see Figure 3a,b, respectively. The Weibull probability distribution function has been used in this study as a damage function on the metallic waste [10], considering that, due to the cutting action of recycled metallic waste, many small cuts occur during each specific industrial process, such as longitudinal cuts for fibres and turning cuts for shavings. From these Figures, a good data fitting is observed due to the fact that all the morphological parameters, regardless of the waste type, can be aligned in a 1:1 straight line. This result was similarly reported in previous studies about the morphological characterisation of recycled metallic fibres added to rubber [33] and asphalt [34] composite materials.  
Moreover, Table 3 presents the results of statistical parameters obtained for the morphological data measured on the 120 shavings and fibres. In this Table, it was proven that the steel shavings (average length 7.181 mm) are on average longer than the steel wool fibres (average length 5.833 mm). Likewise, it was confirmed that the shavings' width (average 1.31 mm) is 10 times greater than the fibres' diameter (Table 3). As a result, the shavings ranged from 3 to 21 mm length, while the fibres ranged from 2 to 14 mm length. Regarding their morphology, the added fibres can be considered as medium-length fibres [33]. In addition, the diameter calculated from the measurement of individual fibres by optical microscope was on average 0.133 mm, so they can be considered as a thick type of fibre [35]. More information on the morphology of the recycled shavings used in this study can be  
Figure 3: Weibull probability-probability plot of the (a) length and width of the metallic shavings and (b) length and diameter of metallic fibres.  
found in the work recently published by [PERSON] et al. (2018). In this study, a classification by typology of the recycled shavings has been developed by using optical microscopy.  
Table 4 shows the basic elemental composition results obtained by EDXS for the metallic waste used in the study. Based on the results, it was proven that steel wool fibres were composed of low-carbon steel, with a bulk density of 7.16 g/cm\({}^{3}\). Likewise, steel shavings were formed of ferritic stainless steel, with a bulk density of 7.95 g/cm\({}^{3}\). These results proved that steel shavings are more brittle and dense than steel wool fibres and, therefore, more susceptible to breakage during the mixing process. This became evident on a few occasions by observing SEM images of shavings and fibres after mixing (Figure 4). Steel shavings appeared to suffer damage as a result of mechanical cleavage during mixing (Figure 4a). In this case, fracture and dislocation of various layers of the steel shavings were apparent. In contrast, steel wool fibres made of low-carbon steel and with an average aspect ratio of 44 were more ductile than shavings. Thus, they did not seem to suffer any damage as a result of mixing. Nonetheless, they were more susceptible to the formation of clusters and aggregations during the mixing process (Figure 4b).