COMPARATIVE INVESTIGATION OF THE COMPRESSIVE STRENGTH OF STEEL FIBER REINFORCED CONCRETE UNDER STATIC AND IMPACT LOADS

Abstract

This study examines the effect of steel fiber content on compressive behavior of concrete under static and impact loading. The results indicate that increasing fiber dosage reduces workability: the mixture with 0.5% fibers reached the highest flowability (245 mm), while higher contents of (1.0-2.0)% progressively decreased it to 195 mm. This reduction is attributed to greater interparticle friction, the disruption of the granular framework, and fiber orientation resisting flow. Compressive strength under static loading exhibited only slight variation (176.97-179.87) MPa, suggesting limited influence of fibers on quasi-static strength. In contrast, impact loading significantly increased the compressive strength (189.54-194.06) MPa and the strain capacity, with corresponding DIF values of approximately 2.7. A fiber content of 1.5% (MT15) provided the best balance between strength and ductility, whereas 2.0% (MT20) produced the highest toughness but was affected by fiber clustering and stress concentration. Dynamic analysis further confirmed consistent improvements in compressive strength (7-8)% across all dosages, while toughness more than doubled under impact conditions, reaching 1.258 MJ/m³ for MT20. These improvements were governed by crack-bridging and fiber pull-out mechanisms, which delayed crack propagation and enhanced energy absorption. An optimal fiber dosage of 1.5% is recommended to balance workability, strength, and toughness in practical applications.