硅酸盐学报

磷酸氢二钾提高硅酸镁水泥早期强度的机理

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冷迪飞 ¹ , 李相国 ¹^,² , 吕阳 ¹ , 李能 ¹

硅酸盐学报 | 化学外加剂助力现代混凝土绿色低碳与高性能化专题—研究论文 2025,53(3): 531-538

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硅酸盐学报 |化学外加剂助力现代混凝土绿色低碳与高性能化专题—研究论文 2025 , 53 (3) : 531 -538

磷酸氢二钾提高硅酸镁水泥早期强度的机理

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冷迪飞¹, 李相国¹^,², 吕阳¹, 李能¹

作者信息

^1．武汉理工大学材料科学与工程学院，硅酸盐建筑材料国家重点实验室，武汉 430070

^2．石河子大学化学化工学院，化工绿色过程省部共建国家重点实验室培育基地，新疆石河子 832000

通讯作者:

李相国（1976—），男，博士，教授。

作者简介:

冷迪飞（1994—），男，博士研究生。

Mechanism of K₂HPO₄ Improving Early Strength of Magnesium Silicate Hydrate Cements

Difei LENG¹, Xiangguo LI¹^,², Yang LV¹, Neng LI¹

Affiliations

^1.State Key Laboratory of Silicate Materials for Architectures, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China

^2.State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832000, Xinjiang, China

Corresponding Author:

LI Xiangguo (1976-), male, Ph.D., Professor. E-mail: lxggroup@163.com

LENG Difei (1994-), male, Doctoral candidate. E-mail: lengdifei@qq.com

出版时间: 2025-03-20 doi: 10.14062/j.issn.0454-5648.20240337

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摘要

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硅酸镁水泥（MSHC）较慢的早期水化速率是限制该种水泥应用规模的主要因素。通过X射线衍射（XRD）精修，²⁹Si核磁共振谱（NMR），扫描电子显微镜（SEM）与密度泛函理论计算探讨了磷酸氢二钾（DKP）加速MSHC水化的机理，证实DKP的引入能够诱导胶凝性更强的水化硅酸镁（M-S-H）结构更快的生成，从而显著提高MSHC的早期强度以及后续强度，其1、3、7、14 d和28 d分别提高3.25、13.78、22.23、34.58 MPa和37.96 MPa。硅酸镁水泥水化产物的XRD精修，²⁹Si NMR，SEM与密度泛函理论计算证实，DKP诱导生成了高杨氏模量和低泊松比的M-S-H，即Superhydrous Phase B。强调这样一种思路，即合适的外加剂能够诱导胶凝性更强的M-S-H结构更快的生成，从而提高水合硅酸镁水泥的水化速度和早期强度，进一步拓展水合硅酸镁水泥的应用范围。

关键词

硅酸镁水泥 / 核磁共振谱 / X射线衍射精修 / 加速水化 / 密度泛函理论 / 磷酸氢二钾

Abstract

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Introduction

Magnesium silicate hydrate (M-S-H) cement is a low-carbon cementitious material. This paper discusses the mechanism of dipotassium phosphate (DKP) accelerating the hydration of hydrated magnesium silicate cement, and confirms that the introduction of DKP accelerated the formation of M-S-H gel due to the alkali induction effect and K-struvite seed crystal induction effect. This improves the compressive strength and subsequent strength of hydrated magnesium silicate cement, which can increase 3.25, 13.78, 22.23, 34.58 MPa and 37.96 MPa at the age of 1, 3, 7, 14 d and 28 d, respectively. Meanwhile, different additives can induce the formation of different M-S-H crystal phases. The acceleration of the hydration process by these additives is confirmed through X-ray diffraction (XRD), ²⁹Si nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM) and density functional theory calculations. M-S-H is the main source of strength for hydrated magnesium silicate cement, and this paper also emphasizes that suitable additives can induce a faster formation of M-S-H structures with stronger cementitious properties, thereby improving the hydration rate and early compressive strength of magnesium silicate hydrate cements, and further expanding the application range of magnesium silicate hydrate cements.

Methods

MgO: SF mass ratio for preparing MSHC samples was 40 ∶ 60 (i.e., the amount of substance was 1∶1), the water/cement (w/c) ratio was 0.45, the SHMP content was 1% (mass fraction) of the total solid mass, and the samples were all cured at 25 ℃ and 95% RH for 28 d. When the samples were cured at different ages (i.e., 1, 3, 7, 14 d and 28 d), they were broken into small pieces with the particle sizes of 1-3 cm and soaked in isopropyl alcohol to stop their further hydration. The broken samples were dried in a vacuum drying oven at 40 ℃ until there was no more mass loss.

The crystal phases of the samples were determined by a model Empyrean Rietveld X-ray diffractometer (XRD, Malvern Panalytical Co., The Netherlands). The morphology of the samples was analyzed by a model JSM-IT300 scanning electron microscope (SEM, JEOL Ltd., Japan). The nuclear magnetic resonance map of the samples was analyzed by a model Advance III 400 nuclear magnetic resonance spectroscope (NMR, Bruker Co., Germany).

This work was also analyzed based on density functional theory calculations (DFT). All the models were geometrically optimized and subsequent calculations were performed by a software named Vienna Ab-initio Simulation Package (VASP). The projection enhanced plane wave method (PAW) was used in the calculation, and the cutoff energy was set to 500 eV, which was obtained after the convergence test. The exchange-correlation potential was approximated by Perdew-Burke-Ernzerhof (PBE) under generalized gradient approximation (GGA). A 15×15×9 K-point grid was used to sample the first Brillouin region for the stress-strain calculation. Young's modulus and Poisson's ratio of each M-S-H crystal phase were calculated via vaspkit.

Results and discussion

The DKP increases the compressive strength of MSHC by 3.25, 13.78, 22.23, 34.58 MPa and 37.96 MPa at 1, 3, 7, 14 d and 28 d, respectively. This mechanism is since the DKP induces the formation of more suitable M-S-H crystal phase with a higher mechanical strength, and the DKP accelerates the hydration rate of M-S-H, especially the early hydration rate. The SEM images confirm the acceleration effect of the DKP on the hydration. The results of Rietveld XRD and DFT calculation indicate that the DKP can induce the formation of M-S-H crystal structure with a greater gellability. The M-S-H crystal phase-D induced by SHMP is of the lowest Young's modulus and the highest Poisson's ratio. Also, its M-S-H crystal phase generation is rather small, compared with other groups, resulting in its lowest theoretical compressive strength. The M-S-H principal crystal phase induced by DKP is a superhydrous phase B, which is of the highest Young's modulus and the lower Poisson's ratio, leading to the highest theoretical compressive strength. This indicates that the DKP induces the formation of M-S-H crystalline phase with a greater compressive strength. The main crystal phase of M-S-H induced by KOH and K-struvite are talc and anthophyllite, respectively, which are of higher Young's modulus and lower Poisson's ratio, thus improving the compressive strength.

Conclusions

The admixture DKP could improve the compressive strength of MSHC via inducing the MSHC system to generate more suitable and higher mechanical strength M-S-H crystal phase, accelerating the hydration process of MSHC, and increasing the compressive strength of MSHC samples (i.e., 3.25, 13.78, 22.23, 34.58 MPa and 37.96 MPa) at different ages (i.e., 1, 3, 7, 14 d and 28 d). The results by Rietveld X-ray diffraction refinement showed that different admixtures induced the hydration of MSHC to form different M-S-H crystal phases, which could affect the cement strength. The DKP induced M-S-H to form a superhydrous phase B, which was a M-S-H crystal phase with a high Young's modulus and a low Poisson's ratio. This was one of the mechanisms due to the DKP enhancing MSHC. This wor'k indicated that suitable admixtures could induce the formation of M-S-H crystal structure with a greater cementitious property, thereby improving the hydration rate and early strength of MSHC.

Key words

magnesium silicate cement / nuclear magnetic resonance spectrum / XRD refinement / accelerate hydration / density functional theory / dipotassium hydrogen phosphate

引用本文

冷迪飞, 李相国, 吕阳, 李能. 磷酸氢二钾提高硅酸镁水泥早期强度的机理. 硅酸盐学报, 2025 , 53 (3) : 531 -538 . DOI: 10.14062/j.issn.0454-5648.20240337

Difei LENG, Xiangguo LI, Yang LV, Neng LI. Mechanism of K₂HPO₄ Improving Early Strength of Magnesium Silicate Hydrate Cements[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (3) : 531 -538 . DOI: 10.14062/j.issn.0454-5648.20240337

基金

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国家自然科学基金面上项目(52172024)
兵团重点领域科技攻关计划项目(2023AB013-03)

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2025年第53卷第3期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240337

接收时间：2024-05-14
首发时间：2026-10-22
出版时间：2025-03-20

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出版历史

收稿日期：2024-05-14
修回日期：2024-05-29

基金

国家自然科学基金面上项目(52172024)

兵团重点领域科技攻关计划项目(2023AB013-03)

作者信息

^1．武汉理工大学材料科学与工程学院，硅酸盐建筑材料国家重点实验室，武汉 430070

^2．石河子大学化学化工学院，化工绿色过程省部共建国家重点实验室培育基地，新疆石河子 832000

通讯作者:

李相国（1976—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240337

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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