PSI - Issue 64

Rosario Lombardi et al. / Procedia Structural Integrity 64 (2024) 1919–1926 Rosario Lombardi et al. / Structural Integrity Procedia 00 (2019) 000 – 000

1924

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therefore more inclined to "collect" PLA during the impregnation phases. For the other two types considered this variation is much less marked. 3.1.3. Ideal cross section and absorption Cross-section From the obtained values of linear density (dry) and density it was possible to obtain an estimation of the cross section of the single yarns as reported in Figure 4.

Figure 4 – Nominal cross section area for coated natural yarns

The nominal cross-section area of the tested natural yarns decreases as the amount of PLA that has impregnated the fiber decreases. This involves an increase in the lateral surface of the yarn, and consequently an increase in the contact area between the yarn and the mortar, once it is immersed within the inorganic matrix. Obviously, this observation is valid having a similar bond between mortar and non-impregnated yarn, and between mortar and impregnated yarn. As for the linear density, also for the area values there is a strong variability of jute, a consequence of a greater deposit of PLA on the latter for low PLA concentrations.

Absorption The results obtained from the calculation of water absorption are shown in Figure 5.

Figure 5 – Absorption capacity results for coated natural yarns

The value in mg/cm of water absorbed by reference value of Flax (265 g/m 2 ) was obtained indirectly starting from the available physical parameters. Observing the results obtained, it is possible to notice how in percentage terms there is a variation in the absorption value that is congruent with the impregnation carried out. However, when we consider the absorption values in weight per unit length, this trend is no longer visible for every textile: in fact, the quantity of absorbed water remains more or less unchanged for Jute (320 g/m 2 ) and Flax (125 g/m 2 ). This can be interpreted as follows: the amount of water absorbed remains the same regardless of the type of impregnation performed, while the overall weight varies. Consequently, the percentage of the dry weight of the sample varies. Ultimately, impregnation of the fabric does not appreciably decrease its water absorption for that type of textiles presented in that configuration.