PSI - Issue 33

Hassan Suiffi et al. / Procedia Structural Integrity 33 (2021) 229 – 236 Hassan suiffi et al/ Structural Integrity Procedia 00 (2019) 000–000

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Fig. 7. Evolution of diffusivity with addition of fibers

In the fire condition, for temperatures of 300 and 600°C, the composite with 0.50% fibers exhibits the least loss in compressive strength, this loss is increased at 6 hours of exposure for the two temperature ranges, the fiber reinforced concrete at 0.50% gains approximately 15.44% in 300°C and approximately 14.58% in 600°C. Analysis of the curves in Fig. 8 (a) and (b) shows that the compressive strength of the 0.50% polypropylene fiber composite remains close to 27 MPa compared to 20 MPa for non-fiber concrete.

(a)

(b) Fig. 8. Evolution of compressive strength (a) at 300°C, (b) at 600°C

5. Conclusion

 The durability was studied using the three main indicators, mainly the porosity accessible to water εb, the gas permeability Kapp.gas and the diffusivity Dns, the analysis of the results obtained places the concrete of fibers of polypropylene in the same class as ordinary concrete, according to the guide of the French civil engineering association AFGC.  Under conditions of very high temperatures, the use of polypropylene fibers in the cement matrix reduces the effect of spalling and bursting of the concrete and consequently improves its durability, the optimal percentage of polypropylene to be used in the concrete for improving fire resistance is about 0.50% by volume fraction.