硅酸盐学报

不同柠檬酸类缓凝剂对水泥水化进程的影响及作用机制

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李欢欢 ¹^,² , 卢子臣 ¹^,² , 尤紫阳 ³ , 张立恒 ¹^,² , 孙振平 ¹^,²

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): 519-530

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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) : 519 -530

不同柠檬酸类缓凝剂对水泥水化进程的影响及作用机制

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李欢欢¹^,², 卢子臣¹^,², 尤紫阳³, 张立恒¹^,², 孙振平¹^,²

作者信息

^1．同济大学先进土木工程材料教育部重点实验室，上海 201804

^2．同济大学材料科学与工程学院，上海 201804

^3．上海城建物资有限公司，上海 200438

通讯作者:

卢子臣（1987—），男，博士，副教授。

孙振平（1969—），男，博士，教授。

作者简介:

李欢欢（1977—），女，博士研究生。

Effect of Citric Acid and Citrates on Hydration and Setting Performance of Cement

Huanhuan LI¹^,², Zichen LU¹^,², Ziyang YOU³, Liheng ZHANG¹^,², Zhenping SUN¹^,²

Affiliations

^1.Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Tongji University, Shanghai 201804, China

^2.School of Materials Science and Engineering, Tongji University, Shanghai 201804, China

^3.Shanghai Urban Construction Material Co., Ltd., Shanghai 200438, China

Corresponding Author:

LU Zichen (1987-), male, Ph.D., Associate Professor; E-mail: luzc@tongji.edu.cn;

SUN Zhenping (1969-), male, Ph.D., Professor. szhp@tongji.edu.cn

LI Huanhuan (1977-), female, Doctoral candidate. E-mail: huanhuanzhf@163.com

出版时间: 2025-03-20 doi: 10.14062/j.issn.0454-5648.20240505

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摘要

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由于水泥成分的复杂性及所用柠檬酸或盐种类的多样性，柠檬酸类缓凝剂的作用效果及作用机理仍未完全探明，本工作通过凝结时间和水化热等测试手段，系统评价了3种不同柠檬酸类缓凝剂（柠檬酸、柠檬酸钠与柠檬酸钾）在不同掺量及不同掺入方式时对无水石膏（AH）水泥及半水石膏（HH）水泥水化性能与凝结时间的影响，并通过吸附量、溶解速率测试等技术探究了其内在机理。结果表明：在AH水泥中，不论柠檬酸类缓凝剂种类及掺入方式，随着缓凝剂掺量的提高，均会引起水泥浆体先缓凝后速凝现象，而在HH水泥中此种高缓凝剂掺量下的异常快凝现象消失，说明水泥中HH的引入有助于解决柠檬酸类缓凝剂在高掺量下出现的异常凝结现象。此外，柠檬酸类缓凝剂的掺入方式也会极大改变其作用效果，相较于先把缓凝剂溶于水再与水泥混合的水掺方式，柠檬酸类缓凝剂先与水泥粉体混合的干掺方式显示出更强缓凝效果。除了吸附作用，柠檬酸类外加剂与钙离子的络合作用对水泥水化过程也起到重要影响。

关键词

水泥水化 / 柠檬酸 / 缓凝剂 / 石膏

Abstract

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Introduction

Retarders are necessary in construction projects such as long-distance transportation, high-temperature construction in summer and large-volume concrete construction. However, in practical applications, abnormal setting phenomena such as rapid or non-setting of concrete often occur due to the possibly incorrect or excessive mixing, which can affect the progress of the project and cause economic losses. It is thus of great significance for accurately regulating the setting and hardening properties of cement-based materials to clarify the cement hydration process and its mechanism under the action of retarders. Citric acid (CA) and its salts (mainly sodium citrate (SC) and potassium citrate (PC)) are commonly used as retarders. However, there are still some controversies about their effect and mechanism in the existing studies. In this paper, CA, SC and PC with different dosages and addition methods were used to clarify the effect and mechanism of these retarders on cement hydration and solve the problem of abnormal setting during the use of such retarders. Their effects on the setting time of cement paste, hydration heat, and adsorption capacity under the action of different sulfate carriers (anhydrite (AH) and hemihydrate (HH)) were investigated. In addition, the possible mechanism was also analyzed.

Methods

A fixed water-to-cement mass ratio of 0.4 was used. The dosage of citric acid and its salt was calculated based on a mass ratio of citrate to cement, and the dosage of citrate ion was 0.045%, 0.090%, 0.180% and 0.360% (mass fraction), respectively. Two addition methods were used, i.e., W addition method and S addition method. For W addition method, the retarders were first dissolved in water and then mixed with cement. For S addition method, the retarders were first mixed with cement as a solid powder, and then the mixture was added to water. Two kinds of cement with different types of sulfate carriers were prepared, i.e., AH-contained cement prepared with anhydrite and HH-contained cement prepared with hemihydrate.

The setting time was measured according to the Chinese standards GB/T 1346—2011. The hydration of cement paste at (25.00±0.02) ℃ was measured by a model TAM Air 8-channel isothermal calorimeter (Newcastle, DE, USA). The adsorption capacity of different retarders after hydrating for 5 min was measured by a model TOC-L total organic carbon analyzer (Shimadzu Co., Japan). The change in conductivity when AH and HH dissolved in CA, SC and PC solutions with a citrate concentration of 0.047 6 mol/L was determined by a model FE38 conductivity meter (Mettler Toledo Co., Switzerland). In addition, the ionic concentrations of calcium and sulfate during the dissolving process were measured by a model 5800 inductively coupled plasma emission spectrometer (Agilent Co., USA).

Results and discussion

The effect of retarders on the cement hydration process can be affected by different addition methods, dosages, cations of retarders and different sulfate types in cement. For cement with different sulfate carriers, the setting time of HH-contained cement is longer than that of AH-contained cement regardless of the dosage of retarder and the addition method used. The abnormal rapid setting phenomenon of retarder can occur in the AH-contained cement rather than in HH-contained cement. Regardless of the type of retarders used, the initial dissolution capacity of HH is greater than that of AH. For different addition methods, the retarder with S addition method shows a greater retarding ability. The effect of citric acid and citrates indicates that the retarding ability of PC is greater than that of SC.

The results of hydration heat show that a phenomenon of abnormal rapid setting in AH-contained cement can be caused due to the rapid hydration of the aluminate-containing phase. The results of conductivity and ionic concentration indicate that HH quickly dissolves and releases sufficient sulfate ions, thus inhibiting a rapid reaction of C₃A and avoiding the occurrence of rapid setting. Moreover, the ability of PC to promote the dissolution of sulfate carrier is greater than that of SC possibly due to its greater complexing ability with calcium ions. Therefore, the complexation can play an important role in determining the effect of retarders.

Conclusions

The type of sulfate carrier in cement could change the effect of citric acid/citrate. For AH-contained cement, there existed a phenomenon of first retarding and then rapid setting with the increase of retarder dosage. Such a phenomenon was avoided in HH-contained cement. The addition method of citric acid/citrate greatly changed its effect. The S addition method of retarders enhanced its retarding ability. The adsorption and complexation of citric acid/citrate with calcium ions both played an important role in determining the cement hydration process.

Key words

cement hydration / citric acid/citrate / retarder / sulfate carrier

引用本文

李欢欢, 卢子臣, 尤紫阳, 张立恒, 孙振平. 不同柠檬酸类缓凝剂对水泥水化进程的影响及作用机制. 硅酸盐学报, 2025 , 53 (3) : 519 -530 . DOI: 10.14062/j.issn.0454-5648.20240505

Huanhuan LI, Zichen LU, Ziyang YOU, Liheng ZHANG, Zhenping SUN. Effect of Citric Acid and Citrates on Hydration and Setting Performance of Cement[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (3) : 519 -530 . DOI: 10.14062/j.issn.0454-5648.20240505

基金

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国家自然基金(52208282)
上海市科委(22dz1208904)
上海市住建委(沪建科2022-002-031)

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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.0454-5648.20240505

接收时间：2024-08-02
首发时间：2026-10-22
出版时间：2025-03-20

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收稿日期：2024-08-02
修回日期：2024-08-29

基金

国家自然基金(52208282)

上海市科委(22dz1208904)

上海市住建委(沪建科2022-002-031)

作者信息

^1．同济大学先进土木工程材料教育部重点实验室，上海 201804

^2．同济大学材料科学与工程学院，上海 201804

^3．上海城建物资有限公司，上海 200438

通讯作者:

卢子臣（1987—），男，博士，副教授。

孙振平（1969—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240505

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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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