哈尔滨工业大学学报  2021, Vol. 53 Issue (1): 176-183  DOI: 10.11918/202001086 0

### 引用本文

LÜ Yuejing, LIU Biao, ZHANG Lei, TANG Wen. Study on pore characteristics of cement stabilized macadam[J]. Journal of Harbin Institute of Technology, 2021, 53(1): 176-183. DOI: 10.11918/202001086.

### 文章历史

1. 武汉科技大学 汽车与交通工程学院，武汉 430065;
2. 交通运输部公路科学研究院，北京 100088

Study on pore characteristics of cement stabilized macadam
LÜ Yuejing1, LIU Biao1, ZHANG Lei2, TANG Wen1
1. School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan 430065, China;
2. Institute of Highway Science, Ministry of Transport, Beijing 100088, China
Abstract: To study the micro pore characteristics of cement stabilized macadam and the change process of pore space structure under load, through the establishment of three-dimensional pore model to quantify the cross section pore and three-dimensional pore, and the conversion of three-dimensional pore network structure, the parameters such as pore coordination number, pore volume and throat length were extracted. The changing process of pore space structure was deduced by studying the changing rule of parameters with the step-by-step load. Results show that the quantitative porosity of cross section and three-dimensional porosity could characterize the pore change of materials. The peaks in m and n regions extended from 12.10% and 10.29% to 13.89% and 13.41%, the peak distribution region in n region spanned 11 layers. The waveforms in the m and n regions changed drastically and the micro structure of the pores changed significantly. The mean value of coordination number changed from less than 0.45 to 0.505 and the small pores in the pore volume occupied 80% of the pore space structure, but the pore volume changed with increasing load. During the gradual loading process of throat, the maximum throat length increased by nearly 2mm, the throat changed from negative to positive and the load changed the pore space structure. The change of pore microstructure and pore space structure resulted in the change of internal structure of materials and the macro failure of materials. Therefore, the macro failure of materials was essentially related to the change of pore structure.
Keywords: porosity    pore network structure    mean value of coordination number    pore volume    throat

1 试验设计 1.1 材料设计

1.2 试件成型

1.3 加载及CT扫描

2 建立三维模型

avizo软件以多层图像连续贴合的方式导入400张CT图像，为保证后续建立的模型与实际试件尺寸一致，需将CT图像导入avizo后，设定计算单位，单位设定为微米(μm)，单体素为100.0 μm *100.0 μm *100.0 μm. CT图像经数值图像处理技术的中值滤波、锐化技术初步处理后，对图像体素的红、绿、蓝三基色合成与渲染，生成芯样三维模型如图 1(d)所示.

 图 1 三维模型流程图 Fig. 1 Three-dimensional model flow chart

3 孔隙三维模型的断面孔隙率与三维孔隙率特性分析

 $P = \frac{{{V_{{\rm{voxel}}}}}}{{{V_{{\rm{TOTAL}}}}}} \times 100\% .{\rm{ }}$ (1)

3.1 断面孔隙率特性

 图 2 N1级配各荷载与断面孔隙率关系趋势波形图 Fig. 2 Waveform chart of relationship between N1 grading load and section porosity

3.2 三维孔隙率特性

 图 3 荷载与三维孔隙率关系趋势图 Fig. 3 Trend of relationship between load and 3D porosity
4 孔隙三维网络结构及参数特性

4.1 孔隙三维网络结构

 图 4 孔隙三维网络结构转换示意图 Fig. 4 Schematic diagram of pore 3D network structure transformation

 ${D_{{\rm{cq}}}} = \sqrt[3]{{\frac{{6{V_{{\rm{pore}}}}}}{{\rm{ \mathsf{ π} }}}}}.$ (2)

 图 5 孔隙三维网络结构 Fig. 5 Pore 3D network structure
4.2 孔隙三维网络结构参数特性

4.2.1 孔隙配位数特性

 图 6 荷载-孔隙配位数百分比 Fig. 6 Load-pore coordination percentage

4.2.2 孔隙体积特性

 图 7 孔隙体积区间分布图 Fig. 7 Interval distribution of pore volume

4.2.3 喉道特性

 图 8 荷载喉道长度分布图 Fig. 8 Distribution diagram of load throat length

5 结论

1) 孔隙三维模型以及转换为孔隙三维网络结构的方式，能演变荷载作用下孔隙细观结构和孔隙空间结构变过过程，孔隙结构剧烈变化促使材料内部结构改变，外部荷载作用与内部结构改变导致材料宏观破坏，因此材料宏观破坏与孔隙结构变化有本质联系.

2) 孔隙三维模型中量化断面孔隙与三维孔隙的方式能表征水稳材料的孔隙细观结构变化；m、n区的波形较剧烈变化，m、n区峰值从12.10%、10.29%分别扩展到13.89%、13.41%，峰值层位跨度为3、11个层位，三维孔隙率先减小后增大的规律，都从细观角度表明逐级荷载改变孔隙结构.

3) 孔隙三维网络模型中配位数最大值由8、9突变为11，配位数均值由小于0.45突变为大于0.5，喉道长度由7.5 mm左右增加到9.3 mm，孔隙体积有孔隙连通、扩展过程，说明荷载作用导致材料孔隙空间结构剧烈变化.