Abstract

Magnesium phosphate cement-based ultra-high-performance concrete (MPC-UHPC) develops strength rapidly but shows unsatisfactory ultimate strength (<150 >MPa). In this study, ultrafine fly ash (UFA) was incorporated in MPC-UHPC to improve mechanical properties. The effect of UFA content, varying from 0 % to 15 %, by weight of binder, on microstructure, fiber pullout behavior, mechanical strengths, flexural and tensile properties of MPC-UHPC reinforced with 2 vol% steel fibers was investigated. Experimental results indicate that the incorporation of 10 %–15 % UFA with mean particle size of 1.4 µm was effective in reducing porosity and microcracks of binder matrix and fiber–matrix interface, thereby resulting in significantly improved fiber–matrix bond properties. The 28-d average bond strength and pullout energy could increase by 27 % and 57 % at 15 % UFA addition, respectively. Such UFA addition level was found to yield a mix with 158.3 MPa compressive strength and substantially enhance the flexural and tensile fracture properties. The result reported herein will further promote the utilization of UFA for the development of MPC materials with outstanding mechanical properties.

Department(s)

Civil, Architectural and Environmental Engineering

Comments

National Natural Science Foundation of China, Grant 52072049

Keywords and Phrases

Fiber–matrix bond; Magnesium phosphate cement; Mechanical properties; Microstructure; Ultra-high performance concrete; Ultrafine fly ash

International Standard Serial Number (ISSN)

0950-0618

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Elsevier, All rights reserved.

Publication Date

18 Oct 2024

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