Open Access

ARTICLE

The Influence of Chemical Admixtures on the Fluidity, Viscosity and Rheological Properties of Ultra-High Performance Concrete

Jin Yang^1,2, Hailong Zhao¹, Jingyi Zeng¹, Ying Su^1,2, Mengdi Zhu¹, Xingyang He^1,2,*

1 School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China
2 Building Waterproof Engineering and Technology Research Center of Hubei Province, Hubei University of Technology, Wuhan, 430068, China

* Corresponding Author: Xingyang He. Email:

Fluid Dynamics & Materials Processing 2024, 20(10), 2163-2181. https://doi.org/10.32604/fdmp.2024.055448

Received 27 June 2024; Accepted 19 August 2024; Issue published 23 September 2024

Abstract

To achieve higher strength and better durability, ultra-high performance concrete (UHPC) typically employs a relatively small water-binder ratio. However, this generally leads to an undesired increase in the paste viscosity. In this study, the effects of liquid and powder polycarboxylate superplasticizers (PCE) on UHPC are compared and critically discussed. Moreover, the following influential factors are considered: air-entraining agents (AE), slump retaining agents (SA), and defoaming agents (DF) and the resulting flow characteristics, mechanical properties, and hydration properties are evaluated assuming UHPC containing 8‰ powder PCE (PCE-based UHPC). It is found that the spread diameter of powder PCE is 5% higher than that of liquid PCE. Among the chemical admixtures studied, AEs have the best effect on improving UHPC workability, while DFs have the worst effect. When the addition of AE and SA is 1.25‰ and 14.7% of PCE, paste viscosity reduces by 35% and 19%, respectively compared to the paste with only 8‰ PCE. A low AE dosage (1.25‰) decreases compressive strength by 4.1%, while SA (8.1%) increases UHPC compressive strength by 9.1%. Both AE and SA significantly delay the UHPC hydration process, reducing the hydration heat release peaks by 76% and 27%, respectively.

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Keywords

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