Mechanical Properties of Cement Mortars Reinforced with Polypropylene Fibers Subjected to High Temperatures and Different Cooling Regimes

This study experimentally investigated the mechanical properties of cement mortars that were reinforced with polypropylene (PP) fibers after being exposed to high temperatures and cooled under different regimes. PP fibers were added in amounts of 2, 3 and 4 kg/m³, the residual strengths of the mortars exposed to various temperatures up to 500 °C and cooled under different regimes were determined. It was found that the addition of PP fiber at the level of 2 kg/m³ improves the residual flexural and compressive strengths up to 300 °C. The residual flexural strength was approximately 75%, which is 15% higher than that observed in the simple mortar, and the same happens with the residual compressive strength which was approximately 85%, which is 17% higher than that observed in the simple mortar, regardless of the types of cooling used on the specimens. It was determined by means of a statistical analysis that there are no significant differences in the mechanical properties of the mortar according to the cooling regimes used, after having been exposed to high temperatures. The correlation of the residual flexural and compressive strengths was achieved with a coefficient of determination, R2 = 0.82, and the relationships between the variables were considered acceptable regardless of the types of cooling used.

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