Title

Development and Characterization of Magnesium Phosphate Cement based Ultra-High Performance Concrete

Abstract

This study aims at the development of magnesium phosphate cement-based ultra-high performance concrete (MPC-UHPC). To this end, MPC paste phase was designed by using high magnesia-to-phosphate (M/P, 3.5) and low water-to-cement (W/C, 0.10-0.16) mass ratios, and certain amounts of ultra-fine fly ash (UFA, 5%-15%). Fresh and hardened properties, and microstructure of the developed MPC-UHPC were evaluated, and compared with those of conventional UHPC as well. Test results showed that lower W/C resulted in higher mechanical strengths and lower drying shrinkage, but the sharp decrease of workability and increase of autogenous shrinkage. At a constant W/C, the addition of UFA effectively improved fresh behaviors and decreased autogenous shrinkage without degrading late-age compressive strength. Due to a good plasticizing effect of UFA, the W/C could be reduced with increasing UFA content, leading in turn to continuous increase in autogenous shrinkage and strength. Compared to conventional UHPC, an optimal MPC-UHPC provided much lower shrinkage, higher early strength, and comparable 28-d strength above 120 MPa. Microstructural analyses revealed that a combination use of high M/P, low W/C and UFA as micro-filler can result in densely compacted microstructure, improved pore structure and enhanced matrix-aggregate interface, which is responsible for the superior mechanical performance of MPC-UHPC.

Department(s)

Civil, Architectural and Environmental Engineering

Comments

The authors would like to acknowledge the financial supports from the National Natural Science Foundation of China (Grant Nos. 52072049 and 51461135003) and the Key Program of Chongqing Science and Technology Innovation and Application Development Project (Grant No. cstc2019jscx-fxydX0038).

Keywords and Phrases

Magnesium phosphate cement; Mechanical properties; Microstructure; Shrinkage; Ultra-fine fly ash; Ultra-high performance concrete

International Standard Serial Number (ISSN)

1359-8368

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2022 Elsevier, All rights reserved.

Publication Date

01 Apr 2022

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