Effect of monopotassium phosphate fineness on properties and micro-characteristics of magnesium potassium phosphate cements

IF 3.4 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY

Materials and Structures Pub Date : 2025-04-30 DOI:10.1617/s11527-025-02646-5

Yizhou Zhao, Biwan Xu

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Abstract

Hydration of magnesium potassium phosphate (MKP) cements is a dissolution–precipitation process. Compared to magnesia, the dissolution effect of monopotassium phosphate (KH₂PO₄) has been gained less attention and remains unclear. In this study influence of two KH₂PO₄ materials with different fineness on properties and micro-characteristics of the MKP cement pastes at Mg/PO₄ molar ratio of 4 and 8 was investigated. Compared with the pastes without boric acid, the effect of KH₂PO₄ fineness was more obvious with the presence of boric acid due to the slowed-down reactions. The combined use of boric acid and the coarse KH₂PO₄ better slowed down the reactions, thus led to longer setting time but to reduced flowability, higher shrinkages and great strength losses. In contrast, the combined use of boric acid and the fine KH₂PO₄ facilitated a better dissolution and consumption of KH₂PO₄ and formations of robust K-struvite hydrates, resulting in less detrimental capillary pores, lower shrinkages and higher strengths, although the reaction could be faster. To guarantee a full consumption of KH₂PO₄ and mitigate strength loss over long-term, Mg/PO₄ molar ratio > 4 and fine KH₂PO₄ are commended for those pure MKP cements.

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磷酸一钾细度对磷酸镁钾胶结物性能和微观特性的影响

磷酸镁钾胶结物的水化是一个溶解-沉淀过程。与氧化镁相比，磷酸一钾（KH2PO4）的溶解作用较少受到关注，目前仍不清楚。研究了两种不同细度的KH2PO4材料在Mg/PO4摩尔比为4和8时对MKP水泥浆体性能和微观特性的影响。与不含硼酸的膏体相比，硼酸的存在使反应减慢，对KH2PO4细度的影响更为明显。硼酸与粗料合用较好地减缓了反应，凝固时间延长，但流动性降低，收缩率增大，强度损失大。相比之下，硼酸与细粒KH2PO4联合使用有利于KH2PO4的溶解和消耗，形成坚固的k -鸟粪石水合物，产生更少的有害毛细孔，更低的收缩率和更高的强度，尽管反应速度可能更快。为了保证KH2PO4的充分消耗和减少长期的强度损失，纯MKP水泥推荐Mg/PO4摩尔比>； 4和细KH2PO4。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials and Structures 工程技术-材料科学：综合

CiteScore

6.40

自引率

7.90%

发文量

222

审稿时长

5.9 months

期刊介绍： Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.