A study on the effects of micro steel fiber content on characteristics of ultra-high performance concrete (UHPC)

Abstract

Concrete is a material that has much lower flexural strength than compressive strength; therefore, previous studies have tried to find the ways to add some types of raw fibers with low contents (due to the effects of aggregate size, they could not be used with high contents) into the concrete mixture including polymer fibers, carbon fibers, steel fibers, and so on to improve the bend strength of concrete. Ultra-high performance concrete (UHPC) uses a large amount of fine particles (less than 0.075 mm), so it has a very high compressive strength and can be added with a large amount of micro steel fiber to improve the bending capacity and change the nature of concrete from a brittle material into a tough and flexible material. In this paper, the authors present the research results of using materials in the Southern Vietnam to produce ultra-high performance steel fiber concrete (UHPSFC) which can achieve the compressive strength up to 140 MPa, and the flexural strength greater than 30 MPa by using micro steel fiber (which has the length of 13 mm, and the diameter of 0.2 mm) with the content up to 4% according to the volume of concrete.