硅酸盐学报

海水与矿物掺合料对水泥基材料微结构和力学性能的影响

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朱德举 ¹^,² , 赵雪薇 ¹ , 郭帅成 ¹^,²

硅酸盐学报 | 研究论文 2024,52(5): 1477-1485

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硅酸盐学报 |研究论文 2024 , 52 (5) : 1477 -1485

海水与矿物掺合料对水泥基材料微结构和力学性能的影响

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朱德举¹^,², 赵雪薇¹, 郭帅成¹^,²

作者信息

^1．湖南大学土木工程学院，长沙 410082

^2．湖南大学绿色先进土木工程材料及应用技术湖南省重点实验室，长沙 410082

通讯作者:

郭帅成（1990—），男，博士，副教授。

作者简介:

朱德举（1978—），男，博士，教授。

Influence of Seawater and Mineral Admixtures on Microstructure and Mechanical Performance of Cement-Based Materials

Deju ZHU¹^,², Xuewei ZHAO¹, Shuaicheng GUO¹^,²

Affiliations

^1.College of Civil Engineering, Hunan University, Changsha 410082, China

^2.Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, Hunan University, Changsha 410082, China

Corresponding Author:

GUO Shuaicheng (1990-), male, Ph.D., Associate Professor. E-mail: scguo@hnu.edu.cn

ZHU Deju (1978-), male, Ph.D., Professor. E-mail: dzhu@hnu.edu.cn

出版时间: 2024-05-20 doi: 10.14062/j.issn.0454-5648.20230820

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摘要

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海水中多元离子会通过参与水化反应改变水泥水化产物组分和微结构，从而影响其力学性能和耐久性。本工作通过对孔溶液离子成分测试和水化产物矿相表征以揭示海水中多元离子与矿物掺合料耦合作用下，水泥基材料微结构和力学性能演化机制。采用离子色谱仪及电感耦合等离子发射光谱仪测得压滤法获得的净浆孔溶液的离子成分，同时结合X射线衍射、热重分析等微观表征研究水化产物矿相的演变规律。结果表明：海水中多元离子会促进水泥中硅酸三钙和硅酸二钙的水化，提高海水净浆孔溶液碱度，加快矿物掺合料与氢氧化钙的二次水化反应。硅灰对于孔溶液碱度的降低效果显著优于粉煤灰，也能通过生成更多水化硅酸钙凝胶实现钠离子和钾离子的有效固化。粉煤灰可以通过促进钙矾石、Friedel's盐等铝相产物生成，实现对氯离子的有效固化，同时固化效果优于硅灰。本工作可以为海水海砂混凝土微结构和力学性能调控提供参考。

关键词

海水海砂混凝土 / 孔溶液 / 水化产物 / 矿物掺合料

Abstract

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Introduction

The utilization of seawater and sea sand for concrete production can effectively relieve the environmental pressure caused by the consumption of freshwater and river sand resources. Previous studies demonstrate that the mechanical properties of seawater sea sand concrete are consistent with those of normal concrete, which can meet the construction needs. However, the multiple element ions in seawater alternate the components and microstructure of hydration products via participating in the hydration reaction, affecting its durability performance. Mineral admixtures can be used to mitigate the possible adverse effects of multiple element ions on cementitious materials. The existing research on the interaction between inorganic ions and the internal microenvironment of cementitious materials mainly focus on the effect of single ions, and the influence mechanism of multiple element ions lacks systematic investigations. Meanwhile, the influence mechanism of mineral admixtures on the performances of seawater sea sand concrete Is still unclear. In this paper, the pore solution composition and the mineral phases of the hydration products were characterized to reveal the evolution mechanism of the internal microenvironment under the coupling effect of multiple element ions in seawater and mineral admixtures.

Methods

A cementitious system was designed via the centroid simplex optimization of Portland cement, fly ash and silica fume. The artificial seawater was prepared according to the standard (ASTM D1141-98) at a pH value of 8.29. Sea sand from Jiaozhou Bay, China, was used as fine aggregates with a fineness modulus of 2.65. The polycarboxylic acid high-performance water reducer with a water reduction rate of 30% was used to adjust the flowability of fresh stage cement paste, (Shanxi Feike New Material Science and Technology Co. Ltd., China). The specimens with a water/binder ratio of 0.35 and a sand/binder ratio of 1.0 were then prepared for characterization, and the water-reducing agent dosage was adjusted to maintain the same fluidity among different sample groups.

After curing for 3, 7 d and 28 d, the ion concentration in pore solution obtained from a pressure filtration method was characterized by inductively coupled plasma emission spectrometry, and its pH value was measured by a pH meter. The phase composition of powder samples after soaking in isopropanol and further drying was characterized by a model MiniFlex 600 X-ray diffractometer. In addition, the thermal behavior of the powdered samples aged at 28 d was determined by thermogravimetric analyzer/derivative thermogravimeter. The compressive strength of cubic mortar specimens with the sizes of 70.7 mm×70.7 mm×70.7 mm aged for 3, 7 d and 28 d was measured.

Results and discussion

The compressive strength of seawater sea sand mortar specimens is higher than that of freshwater river sand mortar specimens aged at 28 d. This can be attributed to the pore filling effect by hydration products and the formation of more compact C-S-H gels in the presence of the multiple element ions.

The multiple ions in seawater also increase the pH value of the pore solution. The pore solution alkalinity can be further regulated via mixing mineral admixtures. At the same dosage, silica fume significantly outperforms that of fly ash in reducing the alkalinity of the seawater cement paste pore solution. Silica fume can nearly consume the calcium hydroxide component at a dosage of 30%, and the pH value of the pore solution decreases to 11.69 at 28 d. Also, silica fume can generate more hydrated calcium silicate gels with a low Ca/Si ratio to enhance its binding ability with sodium and potassium ions, and the enhancement effect is better than that of fly ash. The active aluminum phase in fly ash can promote the generation of aluminum phase products (i.e., AFt and Friedel's salt), and enhance the effective solidification of sulfate and chloride ions. The chloride ion solidification effect of fly ash is better than that of silica fume, and the chloride ion concentration of pore solution can reduce to 0.27 mol/L at the dosage of fly ash of 30%.

Conclusions

The results showed that the multiple element ions in seawater promoted the hydration of tricalcium silicate and dicalcium silicate in cement, increased the alkalinity of seawater cement pate pore solution and accelerated the pozzolanic reaction between mineral admixtures and calcium hydroxide. Silica fume significantly outperformed fly ash in reducing the alkalinity of the pore solution. The effective solidification of sodium and potassium ions was achieved through the generation of more hydrated calcium silicate gel products with silica fume. Fly ash could promote the generation of aluminum phase products (i.e., AFt and Friedel's salt) and enhanced the solidification effect of chloride ions, and its enhancement effect was better than that of silica fume. This study could serve as a solid base for the alkalinity regulation and performance design of seawater sea sand concrete.

Key words

seawater sea sand concrete / pore solution / hydration products / mineral admixtures

引用本文

朱德举, 赵雪薇, 郭帅成. 海水与矿物掺合料对水泥基材料微结构和力学性能的影响. 硅酸盐学报, 2024 , 52 (5) : 1477 -1485 . DOI: 10.14062/j.issn.0454-5648.20230820

Deju ZHU, Xuewei ZHAO, Shuaicheng GUO. Influence of Seawater and Mineral Admixtures on Microstructure and Mechanical Performance of Cement-Based Materials[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (5) : 1477 -1485 . DOI: 10.14062/j.issn.0454-5648.20230820

基金

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国家自然科学基金项目(U1806225; 52208246; U22A20122)
湖南省自然科学基金项目(2023JJ40142)
长沙市自然科学基金项目(kq2202160)
中央高校基本科研业务费项目(531118 010493)

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2024年第52卷第5期

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文章信息

doi: 10.14062/j.issn.0454-5648.20230820

接收时间：2023-10-25
首发时间：2026-10-22
出版时间：2024-05-20

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出版历史

收稿日期：2023-10-25
修回日期：2023-11-10

基金

国家自然科学基金项目(U1806225; 52208246; U22A20122)

湖南省自然科学基金项目(2023JJ40142)

长沙市自然科学基金项目(kq2202160)

中央高校基本科研业务费项目(531118 010493)

作者信息

^1．湖南大学土木工程学院，长沙 410082

^2．湖南大学绿色先进土木工程材料及应用技术湖南省重点实验室，长沙 410082

通讯作者:

郭帅成（1990—），男，博士，副教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20230820

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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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