PSI - Issue 55

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Afif Rahma et al. / Procedia Structural Integrity 55 (2024) 206 – 213 Afif Rahma/ Structural Integrity Procedia 00 (2019) 000 – 000

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M(0) M(0/0)

M(0) M(0/0) 4 cm 8 cm formula

2.5kg/m3 5.0kg/m3 formula

Slump (cm)

Slump (cm)

0 2 4 6 8

0 2 4 6 8

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0

2.5

5

Length of fibre (cm)

Weight of fibers (kg/m 3 )

Figure 4: role of fibre length

Figure 5: role of fibre weight

To control the quantity and the length of fibres, the general relationship, between a slump and either fibre length or weight, is proposed by mathematical simulations following the equations: For length S= 1 [6.2 x10 −2 + (5.42 x10 −2 )L − (3.21x10 −3 )L 2 ] (1) For weight S= 1 [6.16x10 −2 + (8.98x 10 −3 ) W − (8.99x10 −5 ) W 2 ] (2) Where: S slump (cm), L fibre length (cm), W fibre weight (kg/m 3 ). The previous mathematical simulation allows choose the adequate length and quantity, where it seems that the optimal values should be respectively less than 2.5 kg of weight and 4 cm of length. Concrete was subjected to the mono-axial compression test, per set of 5 samples, after an age of 28 days. The control samples (M(0)) collapsed for an average load of 108 kN (4.8MPa) and the collapse shape took a regular pyramid form (Figure 6). Furthermore, the samples M(0/0) collapsed under an average load of 20.9 kN (1.2 MPa), with the drop of strength caused by the huge quantity of water that reached 375 l/m 3 . Whereas the concrete reinforced with polypropylene fibre maintained its cubic shape (figure 7) and recovered some strength according to the length and the fibre ratio (figure 8). Moreover, the specimens are collapsed after a large deformation due to the enormous ductility that the concrete gained by the addition of the fibre, where the deformation (  ) reached a value of 8% for M(8/5.0). 3.2. The compression strength

Figure 6: Collapse form of M(0)

Figure 7: Collapse form of M(4/25)