Relationship between Flowability, Entrapped Air Content and Strength of UHPC Mixtures Containing Different Dosage of Steel Fiber

Rui Wang,Xiaojian Gao

doi:10.3390/app6080216

Abstract

This study investigated the effects of different fiber contents by volume (0%, 1%, 2%, and 3%) on flowability, entrapped air content, and compressive and flexural strength of ultra high performance concrete (UHPC). Four water-to-binder ratios (0.18, 0.20, 0.22, 0.24) were used and four different dosages of superplasticizer were introduced for preparing each water-to-binder ratio mixture. The experimental results reveal that the increased content of fiber decreases the flowability and entrapped air content of fresh UHPC mixtures. The compressive strength of UHPC increased with a greater addition of steel fiber, from 1% to 3%. The flexural strength was increased slightly by the addition of 1% steel fiber and increased remarkably with the addition of 2% and 3% steel fiber. For every water-to-binder ratio mixture, with and without steel fiber, a good linear relationship can be found between compressive strength and entrapped air content. Therefore, it is suggested that lowering the entrapped air provides a significant contribution to increasing compressive strength of UHPC containing higher steel fibers.

Highlights

As a new cement-based material, ultra high performance (UHPC) has gained interest around the world since it was introduced in the early 1990s
Figure presents the effects of steel fiber content, water–binder ratio andwere superplasticizer
The steel fibers were randomly distributed in the mortar matrix and acted as a skeleton, and Figure 6 presents the effects of steel fiber content, water–binder ratio and superplasticizer dosage eventually prevented the flow of fresh ultra high performance concrete (UHPC) mixture [14]

Summary

Introduction

As a new cement-based material, ultra high performance (UHPC) has gained interest around the world since it was introduced in the early 1990s. Ultra high performance concrete (UHPC) can show compressive strength from 150 to 810 MPa [1], approximately 3–16 times that of conventional concrete. Due to the improved mechanical strength, impact resistance, fatigue resistance, and its excellent durability [2,3,4], UHPC is regarded as a construction material for energy saving, material saving, and low carbon emission. The addition of fiber can improve the flexural properties of UHPC, and leads to the transformation from brittle failure to ductile failure [11]. It was reported that the tensile strength of UHPC linearly increased with increased steel fiber volume ratio, from 0% to 5% [12]

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Methods

Results

Conclusion