纳米SiO<sub>2</sub>改性聚合物水泥基复合材料早期微观结构及性能

李刊; 魏智强; 乔宏霞; 路承功; 黄尚攀; 杨博

doi:10.13801/j.cnki.fhclxb.20200218.002

纳米SiO₂改性聚合物水泥基复合材料早期微观结构及性能

doi: 10.13801/j.cnki.fhclxb.20200218.002

李刊^1,,
魏智强^{1, 2,},
乔宏霞^{1, 3, ,},
路承功^1,,
黄尚攀^2,,
杨博^1,

1.
兰州理工大学　土木工程学院，兰州 730050
2.
兰州理工大学　省部共建有色金属先进加工与再利用国家重点实验室，兰州 730050
3.
兰州理工大学　西部土木工程防灾减灾教育部工程研究中心，兰州 730050

基金项目: 国家自然科学基金(51868044)；硅酸盐建筑材料国家重点实验室(武汉理工大学)开放基金(SYSJJ2018-20)；兰州理工大学红柳一流学科建设计划

详细信息

通讯作者:
乔宏霞，博士，教授，博士生导师，研究方向为高性能混凝土耐久性　E-mail：Hongxia_Qiao@163.com

中图分类号: TU528
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- 被引次数: 0
出版历程
- 收稿日期: 2019-10-23
- 录用日期: 2020-01-03
- 网络出版日期: 2020-02-19
- 刊出日期: 2020-09-15

Microstructure and properties of polymer cement-based composites modified by nano SiO₂ in early age

LI Kan^1
,,
WEI Zhiqiang^{1, 2
,},
QIAO Hongxia^{1, 3
, ,},
LU Chenggong^1
,,
HUANG Shangpan^2
,,
YANG Bo^1
,

1.
School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China
2.
State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
3.
Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China

摘要

摘要: 利用纳米SiO₂(nano SiO₂)早期可促进聚合物水泥基复合材料水化速率、提升其力学性能、改善其界面过渡区(ITZ)性能及优化其孔隙结构等特点，借助XRD、SEM、EDS、显微硬度(MH)及压汞(MIP)等试验，揭示了nano SiO₂对聚合物水泥基复合材料早期性能影响的微观机制。结果表明：当nano SiO₂掺量为2wt%时，聚合物水泥基复合材料的力学性能最优，3 d和7 d龄期抗压强度分别为57.5 MPa和67.3 MPa，较仅仅掺加聚合物的水泥基复合材料分别提高了12.7%和13.9%；nano SiO₂的掺入改变了聚合物水泥基复合材料水化产物数量及微观形貌。对于ITZ性能，nano SiO₂掺入后，聚合物水泥硬化浆体-骨料的ITZ厚度减小，形貌变得更加致密；ITZ的钙硅比因nano SiO₂的加入变小而其显微硬度变大；此外，nano SiO₂加入后可以进一步填充聚合物水泥基复合材料更加细小的孔隙，使其凝胶孔比例变高，最可几孔径变小，大大优化了聚合物水泥基复合材料的孔隙结构。
- 纳米SiO₂ /
- 聚合物水泥基复合材料 /
- 微观结构 /
- 界面过渡区 /
- 力学性能
Abstract: Owing to the addition of nano SiO₂ can promote the hydration rate, improve the mechanical properties and interfacial transition zone (ITZ) and refine the pore structure of polymer cement-based composites, the microscopic mechanism of influence of nano SiO₂ on the early properties of polymer cement-based composites was revealed by means of XRD, SEM, EDS, microhardness (MH) and mercury intrusion porosimetry (MIP) experiments. The results show that when nano SiO₂ content is 2wt%, the mechanical properties of the polymer cement-based composites are the best. The compressive strength is 57.5 MPa and 67.3 MPa in 3 d and 7 d age, respectively, which is 12.7% and 13.9% higher than that of the polymer cement-based composites with polymer simply. The addition of nano SiO₂ changes the hydration products and microstructure of the polymer cement-based composites. As for ITZ, the thickness of ITZ between polymer cement hardened paste and aggregate decreases, its morphology becomes denser, the calcium-silicate ratio in ITZ declines and the microhardness in ITZ increases by nano SiO₂ incorporation. Since nano SiO₂ can further fill finer pores of the polymer cement-based composites, there is higher proportion of gel pores and the mean pore diameter tends to be smaller so that the pore structure of the polymer cement-based composites is greatly optimized by nano SiO₂ addition.
- nano SiO₂ /
- polymer cement-based composites /
- microstructure /
- interfacial transition zone /
- mechanical properties

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图 1 nano SiO₂的TEM图像

Figure 1. TEM image of nano SiO₂

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图 2 SEM及压汞(MIP)试验待测试样

Figure 2. Test samples of SEM and mercury intrusion porosimetry(MIP) tests

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图 3 NCM、PCM及nano SiO₂/PCM复合材料的早期力学性能

Figure 3. Mechanical properties of NCM, PCM and nano SiO₂/PCM composite in early age

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图 4 NCM、PCM及nano SiO₂/PCM复合材料3 d水化产物的XRD图谱

Figure 4. XRD patterns of hydrate of NCM, PCM and nano SiO₂/PCM composite at 3 d age

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图 5 NCM、PCM及nano SiO₂/PCM复合材料3 d的SEM图像

Figure 5. SEM images of NCM, PCM and nano SiO₂/PCM composite at 3 d age

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图 6 基准水泥净浆(NCP)、聚合物水泥净浆(PCP)及nano SiO₂改性PCP(nano SiO₂/PCP)复合材料硬化浆体-骨料界面过渡区(ITZ) 7 d龄期的SEM图像

Figure 6. SEM images of hardened cement paste-aggregate bonding ITZ of normal cementpaste(NCP), polymer cement paste(PCP) and PCP modified by nano SiO₂(nano SiO₂/PCP) composite at 7 d age

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图 7 NCP、PCP及nano SiO₂/PCP复合材料硬化浆体-骨料ITZ的采样点分布及7 d 龄期的EDS图谱

Figure 7. Distribution of sampling points and EDS spectra of hardened cement paste-aggregate bonding ITZ of NCP, PCP and nano SiO₂/PCP composite at 7 d age

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图 8 NCP、PCP及nano SiO₂/PCP复合材料硬化浆体-骨料ITZ的钙硅原子比

Figure 8. Ca/Si atomic ratios of hardened cement paste-aggregate bonding ITZ of NCP, PCP and nano SiO₂/PCP composite

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图 9 NCP、PCP及nano SiO₂/PCP复合材料硬化浆体-骨料ITZ的7 d龄期显微硬度

Figure 9. Microhardness of hardened cement paste-aggregate bonding ITZ of NCP, PCP and nano SiO₂/PCP composite at 7 d age

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图 10 NCP、PCP及nano SiO₂/PCP复合材料硬化浆体-骨料ITZ及硬化浆体内部7 d龄期的显微硬度

Figure 10. Microhardness of hardened cement paste-aggregate bonding ITZ and inside hardened cement paste of NCP, PCP and nano SiO₂/PCP composite at 7 d age

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图 11 NCM、PCM及nano SiO₂/PCM复合材料3 d龄期孔径分布

Figure 11. Pore diameter distribution of NCM, PCM and nano SiO₂/PCM composite at 3 d age

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图 12 NCM、PCM及nano SiO₂/PCM复合材料3 d龄期的孔径微分分布曲线

Figure 12. Differential distribution of NCM, PCM and nano SiO₂/PCM composite at 3 d age

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表 1 可再分散醋酸乙烯/乙烯共聚(VAE)胶粉基本性能

Table 1. Basic properties of redispersible vinyl acetate/ ethylene(VAE) copolymer latex powder

Performance	Index
Solid content/%	99±1
Apparent density/(g·L⁻¹)	540±50
Appearance	White powder
Steady state material	Poval
Film-forming temperature/℃	4
Particle size/μm	0.5–8

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表 2 纳米SiO₂(nano SiO₂)基本性能

Table 2. Basic properties of nano SiO₂

SiO₂/%	Appearance	Average size/nm	Specific surface area/(m²·g⁻¹)
≥99.5	White powder	20±5	250±30

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表 3 基准水泥砂浆(NCM)、聚合物水泥砂浆(PCM)及nano SiO₂改性PCM(nano SiO₂/PCM)复合材料配合比

Table 3. Mix proportions of normal cement mortar(NCM), polymer cement mortar(PCM) and PCM modified by nano SiO₂(nano SiO₂/PCM) composite

Sample	Cement/g	Water/g	Sand/g	Fly ash/g	nano SiO₂/wt%	VAE/wt%	Water reducer/wt%	Defoamer/wt%	Fluidity/mm
NCM	720	240	1 200	80	0	0	0.20	0	160
PCM	720	240	1 200	80	0	4	0.15	0.1	180
nano SiO₂/PCM	704	240	1 200	80	2	4	0.45	0.1	160

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表 4 NCM、PCM及nano SiO₂/PCM复合材料3 d龄期的孔结构参数

Table 4. Pore structure parameters of NCM, PCM and nano SiO₂/PCM composite at 3 d age

Sample	Porosity/%	Total pore area/(m²·g⁻¹)	Average pore diameter/nm	Median pore diameter/nm
NCM	19.2	19.7	19.8	31.1
PCM	21.0	25.7	17.9	18.3
nano SiO₂/PCM	20.2	28.3	15.5	17.9

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