PSI - Issue 64

Agostino Walter Bruno et al. / Procedia Structural Integrity 64 (2024) 1411–1418 Bruno et al. / Structural Integrity Procedia 00 (2019) 000 – 000 3 of the soil particles was determined as the average of three independent tests performed in agreement with the norm NF P 94-054 (AFNOR, 1991) and it was equal to 2.66 and 2.65 for the Nagen and Bouisset earths, respectively. 1413

Fig. 1. Grain size distribution curves of the Nagen (red) and Bouisset (black) earths.

Fig. 2. Plasticity properties of the Nagen (red) and Bouisset (black) earths.

Both Nagen and Bouisset earths (Figure 3a) were statically compacted in prismatic samples with size of 40×40×160 mm 3 (Figure 3 c) at the target dry density of 1900 kg/m 3 , which is consistent with the typical dry densities of earth materials employed for load bearing construction. Before compaction, each earth was dry mixed with flax fibers of maximum 10 mm length (Figure 3 b) at percentages of 0% (i.e. no fiber addition), 0.5% and 1% by volume. The earth fibers mixes were then moistened at a water content of 12.0% and stored inside sealed plastic bags for about 24 hours to ensure an even distribution of moisture inside the material before being compacted inside stiff molds. Water content was selected as it represents the optimum value for the target dry density for both Nagen and Bouisset earths. Note that water content was maintained constant for fiber reinforced samples, thus assuming that fiber addition did not modify the compaction characteristics of the material. After compaction, samples were equalized to laboratory conditions (i.e. T = 24 ± 1 °C and RH = 73 ± 5 %) until their mass varied less than 0.1% over a minimum period of one week and for at least two weeks (see Bruno et al., 2018, and Cuccurullo et al., 2022) before being subjected to mechanical and thermal tests as described in the following sections.