硅酸盐学报

硫酸盐侵蚀作用下水化硅酸钙分子结构演变及劣化机理

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王慕涵 ¹^,² , 刘程博 ¹ , 王蒙 ¹ , 周向明 ² , 王攀 ¹ , 侯东帅 ¹

硅酸盐学报 | 混凝土耐久性机理表征与预测方法专题—研究论文 2026,54(2): 580-589

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硅酸盐学报 |混凝土耐久性机理表征与预测方法专题—研究论文 2026 , 54 (2) : 580 -589

硫酸盐侵蚀作用下水化硅酸钙分子结构演变及劣化机理

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王慕涵¹^,², 刘程博¹, 王蒙¹, 周向明², 王攀¹, 侯东帅¹

作者信息

^1．青岛理工大学土木工程学院，山东青岛 266520，中国

^2．布鲁内尔大学土木与环境工程系，伦敦 UB8 3PH，英国

通讯作者:

侯东帅（1986—），男，博士，教授。

作者简介:

王慕涵（1991—），男，博士，副教授。

Structural Evolution and Deterioration of Calcium Silicate Hydrate Under Sulfate Attack

Muhan WANG¹^,², Chengbo LIU¹, Meng WANG¹, Xiangming ZHOU², Pan WANG¹, Dongshuai HOU¹

Affiliations

^1.Department of Civil Engineering, Qingdao University of Technology, Qingdao 266520, Shandong, China

^2.Department of Civil and Environmental Engineering, Brunel University London, London UB8 3PH, United Kingdom

Corresponding Author:

Hou Dongshuai (1986-), male, Ph.D., Professor. E-mail: dshou@outlook.com

WANG Muhan (1991-), male, Ph.D., Associate Professor. E-mail: wangmuhan@qut.edu.cn

出版时间: 2026-02-20 doi: 10.14062/j.issn.0454-5648.20250224

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摘要

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海洋环境中的硫酸盐侵蚀是导致混凝土基础设施耐久性降低的关键因素之一，其主要通过破坏混凝土中水化硅酸钙（C-S-H）的微观结构，进而影响材料的力学性能。C-S-H作为水泥水化的主要产物，其结构稳定性直接决定了混凝土的整体性能。本研究通过基于半经验量子力学理论的分子动力学模拟和密度泛函理论，系统研究了C-S-H在硫酸盐侵蚀下的脱钙行为及其结构劣化机制。结果表明，SO₄^2-通过库仑相互作用与Ca²⁺形成反应前驱体，并因其强电子定域性促使Ca²⁺从硅酸盐链中脱离，生成硫酸钙（[CaSiO₃]_n + [SO₄^2-]_m → [SiO₃^2-]_n_-_m + [CaSO₄]_m）。水环境在这一过程中起到了显著的促进作用，Ca²⁺因其水化层的稳定作用而在水相中更易迁移。此外，Ca²⁺的脱离导致[SiO₃^2-]_n_-_m硅酸盐链上产生强烈的静电斥力，引发化学键伸长，最终导致二氧化硅四面体单元（SiO₃^2-）之间的Si—O键断裂，形成大量[SiO₃^2-]_k短链，显著降低了C-S-H的聚合度。本研究揭示了硫酸盐诱导C-S-H脱钙的微观机制，并表明水环境为这一过程提供了有利条件。基于此，增强C-S-H表面的疏水性被证明是抑制硫酸盐脱钙、提高水泥基材料耐久性的有效策略。研究结果为提升海洋环境中混凝土材料抗硫酸盐侵蚀性能提供了理论依据。

关键词

耐久性 / 硫酸盐侵蚀 / 水化硅酸钙 / 分子动力学 / 密度泛函理论

Abstract

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Introduction

It is vital to maintain the durability of construction materials since sulfate attack is a primary factor influencing the lifespan of concrete in marine setting. Sulfate ions (SO₄^2-) degrade concrete via attacking the calcium silicate hydrate (C-S-H) that is the primary hydration product of cement and the binding phase in concrete. This process primarily occurs through calcium leaching, where Ca²⁺ reacts with sulfates to form gypsum, altering pore structure and weakening mechanical properties. C-S-H exhibits a "long-range disorder, short-range order" molecular structure, consisting of nano-scale particles. It is indicated that sulfate-induced degradation involves a competition between SO₄^2- and silicate ions (SiO₃^2-) for Ca²⁺, leading to a material destabilization. The simulations by molecular dynamics (MD) and quantum chemistry (QC) provide insights into this phenomenon, but they have limitations, i.e., MD lacks chemical reaction accuracy, while QC is restricted in a scale. Understanding the molecular interactions governing Ca²⁺ transfer from SiO₃^2- to SO₄^2- is essential for decoding sulfate-induced degradation. However, the existing experimental and computational methods struggle to capture this process comprehensively. A more effective approach is required to accurately simulate chemical reactions and address the dynamics of Ca²⁺ transport in C-S-H degradation.

Methods

This study was to construct a C-S-H model based on tobermorite's unit cell structure, optimizing elemental balance to achieve a Ca/Si ratio of 1.5. The energy minimization was performed by the GFN-xTB method, with the model embedded within a 13 Å water sphere to simulate aqueous conditions. The simulations by Born-Oppenheimer Molecular Dynamics (BOMD) employing the GFN-xTB method investigated the C-S-H decalcification under sulfate attacks. Two 100 ps NVT ensemble simulations at 298.15 K were conducted, i.e., one in pure water and another in sulfate solution (with one SO₄^2- molecule analyzed for Ca²+detachment). The atomic structures were visualized using VMD. The calculations based on Complementary Density Functional Theory (DFT) (Gaussian 16) focused on critical decalcification steps, isolating structural regions (SO₄^2-, desorbed Ca²⁺, and Si—O tetrahedra). The PBE0 hybrid functional and def2-TZVP basis set were used for single-point energy calculations, with DFT-D3 dispersion correction addressing weak interactions.

Results and discussion

This study investigates the decalcification kinetics and structural evolution of C-S-H under sulfate attack using molecular dynamics simulations. In pure water, C-S-H experiences minor structural changes, with surface calcium ions partially dissociating but remaining adsorbed. However, in a sulfate solution, calcium ions desorb rapidly upon sulfate introduction, leading to a structural fragmentation, including Q² to Q¹ transitions and severe silicate chain distortions. The analysis by reduced density gradient (RDG) reveals sulfate's stronger interaction with Ca²⁺, compared to silicate, facilitating calcium extraction. The analysis by electron localization function (ELF) shows a weak Ca—O_Si bonding, while Ca—O_Sul exhibits a stronger electronic localization, promoting calcium displacement. The analysis by bond critical point (BCP) indicates non-covalent interactions drive decalcification, with competitive binding between sulfate and silicate.

The analysis by electrostatic potential (ESP) indicates an increased C-S-H electronegativity post-decalcification, destabilizing the structure. The energy barrier calculations show that sulfate significantly lowers decalcification and silicate chain fracture barriers, weakening C-S-H integrity. Water further amplifies sulfate-induced degradation, enhancing polarity and self-expansion effects. These findings demonstrate that sulfate corrosion accelerates C-S-H structural failure through enhanced calcium extraction, increased electronegativity, and silicate chain fracture, ultimately compromising mechanical properties.

Conclusions

This study explored C-S-H decalcification and degradation under sulfate attack using quantum chemistry and DFT. Sulfate ions could extract calcium via the Coulomb interactions, confirmed by RDG and BCP analysis. The decalcification could destabilize C-S-H, increasing silicate chain electronegativity, expanding Si—O bonds, and reducing dissociation energy. Silicate chain fractures caused C-S-H gel collapse, weakening cementitious materials. Water could facilitate a degradation via lowering energy barriers and enhancing hydrogen bonding with silicate chains, accelerating structural breakdown. These findings could reveal the fundamental mechanisms of sulfate-induced C-S-H deterioration, thus providing insights into material performance under aggressive environments.

Key words

durability / sulfate attack / calcium silicate hydrate / molecular dynamics / density functional theory

引用本文

王慕涵, 刘程博, 王蒙, 周向明, 王攀, 侯东帅. 硫酸盐侵蚀作用下水化硅酸钙分子结构演变及劣化机理. 硅酸盐学报, 2026 , 54 (2) : 580 -589 . DOI: 10.14062/j.issn.0454-5648.20250224

Muhan WANG, Chengbo LIU, Meng WANG, Xiangming ZHOU, Pan WANG, Dongshuai HOU. Structural Evolution and Deterioration of Calcium Silicate Hydrate Under Sulfate Attack[J]. Journal of the Chinese Ceramic Society, 2026 , 54 (2) : 580 -589 . DOI: 10.14062/j.issn.0454-5648.20250224

基金

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国家重点研发计划(2022YFE0133800)

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2026年第54卷第2期

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文章信息

doi: 10.14062/j.issn.0454-5648.20250224

接收时间：2025-03-28
首发时间：2026-10-27
出版时间：2026-02-20

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出版历史

收稿日期：2025-03-28
修回日期：2025-04-17

基金

国家重点研发计划(2022YFE0133800)

作者信息

^1．青岛理工大学土木工程学院，山东青岛 266520，中国

^2．布鲁内尔大学土木与环境工程系，伦敦 UB8 3PH，英国

通讯作者:

侯东帅（1986—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20250224

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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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