PSI - Issue 72

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

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3.2. Ultimate load In fact, in this part, the results of the bending tests will be presented. Table 2 shows the average results obtained from the three specimens tested in each series. The objective of this study was to explore the possibility of using bio based materials in the reinforcement of mortar. And to study the influence of the hemp fiber fabric's position and number of layers on the ultimate load. The results clearly show that the ultimate load is greatest at the fibred of the most tensioned beam. The layer at 0cm positively affects the ultimate load with one increase of 48.5%.

Table 2. Experimental results of bending tests Specimen C F0

F1

F2 1.8

Fu [kN]

1.63

2.42 48.5

1.49

Load gain (%)

-

-

10

3.3. Effect of strengthening E ffect of different positions of layer

Figures 6, 7, and 8 show the force-displacement curves during three-point bending tests for the different series of specimens. All curves exhibit a quasi-linear initial phase, followed by a marked slope, which represents the appearance of the flexural crack. After that, an increase in the load up to its maximum value for the different series was observed.

Fig. 6. Comparison between the control specimens C and specimen F0 Fig. 7. Comparison between control specimens C and specimenF1 Figure 6 compares the behavior of a reinforced specimen with hemp fiber fabrics positioned 0 cm (F0), from the bottom of the beam and the control specimen without strengthening (C) during the bending test. The curves load displacement shows that reinforcing with a single layer at the bottom of the specimen (F0) is of particular importance for delaying the bending crack and increasing the ultimate load. Figure 7 shows the behavior of the reinforced specimen with hemp fiber fabrics positioned 1cm, from the bottom of the beam compared to the control specimen without strengthening. In this case, the results show that a single-layer reinforcement placed on 1cm (F1) from the bottom of the specimen does not affect the ultimate load. The curves have similar behavior.