硫酸铝和偏铝酸钠对水泥浆体强度发展的影响机理
作者:
作者单位:

1.清华大学 土木工程系,北京 100084;2.河北清华发展研究院 先进建筑功能材料创新中心,河北 廊坊 056306;3.山西佳维新材料股份有限公司,山西 运城 044200

作者简介:

廖嘉欣(1998—),女,四川遂宁人,清华大学博士生.E-mail:liaojiaxinne@163.com

通讯作者:

孔祥明(1974—),男,山西平遥人,清华大学教授,博士生导师,博士.E-mail:kxm@mail.tsinghua.edu.cn

中图分类号:

TU528.01

基金项目:

运城市揭榜挂帅项目


Impact Mechanism of Aluminum Sulfate and Sodium Aluminate on Strength Development of Cement Mortars
Author:
Affiliation:

1.Department of Civil Engineering, Tsinghua University, Beijing 100084, China;2.Advanced Building Functional Materials Innovation Center, Hebei-Tsinghua Development Research Institute, Langfang 056306, China;3.Shanxi Jiawei New Material Co., Ltd., Yuncheng 044200, China

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    摘要:

    利用水化量热仪、热重分析仪、X-射线衍射仪、电感耦合等离子体发射光谱仪、压汞仪及扫描电镜等测试手段,建立了水泥浆体水化过程和力学性能之间的关系,揭示了硫酸铝(AS)和偏铝酸钠(NA)对水泥浆体强度发展的影响机理. 结果表明:在相同掺量下,AS和NA对水泥浆体水化过程的影响和促凝早强机理完全不同,AS对水泥浆体硫酸盐平衡没有显著影响,但NA使水泥浆体成为欠硫体系,显著改变了体系的溶解沉淀平衡;水泥砂浆抗压强度的发展同时受硅相反应程度和浆体微结构建立过程的影响;水泥砂浆的早龄期强度不仅源自水泥水化的非晶相产物,钙矾石(AFt)和单硫型水化硫铝酸钙(AFm)等晶相产物也对早期强度有所贡献;与AFm相比,早期生成的AFt更有利于水泥浆体建立良好的早期固体网络结构,从而促进浆体后期强度的发展.

    Abstract:

    Multiple techniques including calorimetry, thermogravimetric analysis, X-ray diffractometer, mercury intrusion porosimeter, inductively coupled plasma optical emission spectrometer and scanning electronic microscope were employed to establish quantitative relationships between hydration products and mechanical properties of cement mortars. The impact mechanisms of aluminum sulfate(AS) and sodium aluminate(NA) on the strength development of cement mortars was revealed. The results indicate that at the same dosage, AS and NA perform different mechanisms in affecting the early strength growth of cement mortars. AS does not significantly affect the sulfate equilibrium of the cement paste, whereas NA turns the cement paste into an under-sulfated system. NA significantly alters the dissolution-precipitation equilibrium of the cement paste. It is found that the compressive strength of cement mortars is affected by the hydration degree of silicate phase and the process of structure build-up. The early-age strength of mortar is not only derived from the amorphous hydration products, but also from the crystalline products such as ettringite(AFt)and monosulfoaluminate(AFm). Moreover, the formation of AFt in early stage other than AFm is more conducive to the establishment of a good early-stage solid network structure of cement paste, thus promoting the development of its later strength.

    图1 水泥砂浆的抗压强度Fig.1 Compressive strength of cement mortars
    图2 水泥净浆超声抗压强度的发展Fig.2 Ultrasonic compressive strength development of cement pastes
    图3 水泥净浆的水化放热曲线Fig.3 Calorimetric curves of cement pastes
    图4 水泥净浆中各物相含量随龄期的变化Fig.4 Changes of amounts of phases in cement pastes with ages
    图5 水泥浆体在3、28 d龄期时的孔结构Fig.5 Pore structure of cement pastes at age of 3 d and 28 d
    图6 水泥净浆在24 h龄期时的SEM照片Fig.6 SEM images of cement pastes at age of 24 h
    图7 水泥净浆水化热与强度发展的关系Fig.7 Relationship between hydration heat and strength development of cement pastes
    图8 水泥砂浆水化产物生成量与强度发展的关系Fig.8 Relationship between amount of hydration products and strength development of cement mortars
    表 1 水泥的化学组成Table 1 Chemical composition(by mass) of cement
    表 2 水泥的矿物组成Table 2 Mineralogical composition(by mass) of cement
    表 3 AS饱和溶液及NA溶液的性质Table 3 Characteristics of AS and NA solutions
    表 4 掺入外加剂后水泥浆体的初始n(SO3)/n(Al2O3)及体系状态Table 4 Initial n(SO3)/n(Al2O3) and state of cement pastes with addition of admixtures
    表 5 砂浆的配合比Table 5 Mix proportions of mortars
    表 6 水泥净浆的凝结时间Table 6 Setting time of cement pastes
    表 7 不同龄期水泥净浆样品中化学结合水和CH的含量Table 7 Contents of CBW and CH in cement pastes at different ages
    表 8 水泥浆体5 min和6 h时孔溶液的pH值和离子浓度Table 8 pH value and ion concentration in pore solutions of cement pastes at 5 min and 6 h
    表 9 AS和NA对水泥浆体凝结和强度发展影响的机理Table 9 Mechanism of accelerated setting and strength development induced by AS and NA
    图1 水泥砂浆的抗压强度Fig.1 Compressive strength of cement mortars
    图2 水泥净浆超声抗压强度的发展Fig.2 Ultrasonic compressive strength development of cement pastes
    图3 水泥净浆的水化放热曲线Fig.3 Calorimetric curves of cement pastes
    图4 水泥净浆中各物相含量随龄期的变化Fig.4 Changes of amounts of phases in cement pastes with ages
    图5 水泥浆体在3、28 d龄期时的孔结构Fig.5 Pore structure of cement pastes at age of 3 d and 28 d
    图6 水泥净浆在24 h龄期时的SEM照片Fig.6 SEM images of cement pastes at age of 24 h
    图7 水泥净浆水化热与强度发展的关系Fig.7 Relationship between hydration heat and strength development of cement pastes
    图8 水泥砂浆水化产物生成量与强度发展的关系Fig.8 Relationship between amount of hydration products and strength development of cement mortars
    表 1 水泥的化学组成Table 1 Chemical composition(by mass) of cement
    表 2 水泥的矿物组成Table 2 Mineralogical composition(by mass) of cement
    表 3 AS饱和溶液及NA溶液的性质Table 3 Characteristics of AS and NA solutions
    表 4 掺入外加剂后水泥浆体的初始n(SO3)/n(Al2O3)及体系状态Table 4 Initial n(SO3)/n(Al2O3) and state of cement pastes with addition of admixtures
    表 5 砂浆的配合比Table 5 Mix proportions of mortars
    表 6 水泥净浆的凝结时间Table 6 Setting time of cement pastes
    表 7 不同龄期水泥净浆样品中化学结合水和CH的含量Table 7 Contents of CBW and CH in cement pastes at different ages
    表 8 水泥浆体5 min和6 h时孔溶液的pH值和离子浓度Table 8 pH value and ion concentration in pore solutions of cement pastes at 5 min and 6 h
    表 9 AS和NA对水泥浆体凝结和强度发展影响的机理Table 9 Mechanism of accelerated setting and strength development induced by AS and NA
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廖嘉欣,王健,孔祥明,徐忠洲,周普玉.硫酸铝和偏铝酸钠对水泥浆体强度发展的影响机理[J].建筑材料学报,2024,27(12):1071-1080

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  • 收稿日期:2024-06-07
  • 最后修改日期:2024-07-18
  • 在线发布日期: 2025-01-21
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