PSI - Issue 72

Ivelina Ivanova et al. / Procedia Structural Integrity 72 (2025) 338–344

340

positioned 0 cm from the bottom of the specimen (see Fig. 1b), designated as F0, like Fabric in 0 cm. The third series was the reinforced specimen with one layer of hemp fabrics positioned 1 cm from the bottom of the specimen (see Fig. 1c), designated as F1, like Fabric in 1 cm. The fourth series, F2, was the reinforced specimen with two layers of hemp fabrics positioned at 0cm and at 1 cm from the bottom of the specimen (see Fig. 1d). 2.1. Materials and methods The materials used were mortar and hemp fiber fabrics. The mortar was prepared with Portland cement CEM II 32.5 R and rolled gravel-dried sand with a maximum grain size of 12 mm was used in the study. Cement: Sand mixture ratio was 1:3. The water for the mixture was used with a ratio W/C=0.5 (see Table 1). It is the same composition as all our samples.

Table 1. Mortar composition Specimen

Sand (g)

Cement (g)

Water (ml)

W/C

All specimens 1350

450

245

0.5

For each type of series three test specimens were manufactured. The hemp fiber fabrics with meshes of 3x3mm were used (see Fig.2a). It was placed in the dry state directly on the formwork for series F0 (see Fig.2b) and F2 or 1 cm on the mortar for series F1. After 24 hours, the samples were removed from the fromwork. a) b) c)

Fig. 2. (a) Hemp fibers fabric reinforcement (b) Fiber fabric directly placed in the formwork; (c) Mortar specimens;

2.2. Experimental tests

Mechanical characterization tensile tests of hemp fiber materials. The experimental program began with the tensile test of a hemp fiber (Fig.3a), then a fabric of hemp fiber fabrics (Fig.3b). The room temperature and pressure conditions were constant. The mechanical behavior was measured through a tensile test on sample specimens. Figure 3 shows the testing machine. The ultimate tensile strength of each sample was determined.