Influence of Type and Volume Content of Steel Fiber on the Compressive Strength of Ultra-High Performance Fiber Reinforced Concrete

Abstract

The paper presents the results of determining the compressive strength of various compositions of Ultra-High Performance Fiber Reinforced concrete (UHPFRC) with fiber volume content from 1 to 3%. Four types of fibers were used: corrugated fiber of 15/0.3 mm and 22/0.3 mm, straight fiber of 13/0.3 mm and hooked-end fiber of 30/0.5 mm. It was found that corrugated and hooked-end fiber leads to an increase in compressive strength by 10–30 MPa when its content is increased from 1 to 3%. Straight fiber has no noticeable effect on the mechanical properties of UHPFRC. Empirical equations for predicting the compressive strength of UHPFRC depending on the strength of concrete matrix, geometric dimensions and content of dispersed reinforcement for compositions with corrugated and hooked-end fibers have been obtained. It is found that increasing the volume content of aggregate in the concrete matrix composition from 0.2 to 0.4 m3/m3 leads to an increase in the strength of UHPFRC. The strength of specimens with corrugated fiber increased by 5.3–13.3 MPa, with hooked-end fiber – by 14–19.3 MPa, with straight fiber – 5–7 MPa. It is also noted that the most intensive growth of mechanical characteristics due to the increase in the aggregate volume content in the composition is observed at a higher percentage of fiber volume fraction.