Study on the mechanical properties of high-strength concrete using high-volume fly ash with different combinations of fiber types and contents

Abstract

This paper presents the results of research on using fly ash (FA) from the Vinh Tan thermal power plant with high content and Southern raw materials, steel fiber (SF), and Polypropylene fiber (PP) to make reinforced concrete. This type of concrete can achieve a 28-day design compressive strength of more than 60 MPa, however, there are actual samples that reach over 80 MPa. Research on concrete mixes at steel fiber volume mixing ratios of 0,5%; 1,0%, 1,5%, PP fiber mixing ratio is 1,5%, and mixed gradation 0,75% SF and 0,75% PP. It was found that when adding steel fibers and PP fibers to the concrete mixture, the slump decreased, especially PP fibers decreased sharply from 17cm to 4cm; Compressive strength and tensile strength when being split at 28 days also increased by 10% to 15% compared to samples without fibers; Water absorption also decreases sharply because the concrete structure becomes denser when adding fibers and the mechanism of action of fly ash. The study proposes a reasonable mixing ratio of concrete of 0,75% SF and 0,75% PP to simultaneously meet the criteria of workability, strength, water absorption, and cost.