基于核磁共振技术分析骨料粒径对水泥砂浆微观结构的影响

摘要/Abstract

摘要： 为研究骨料粒径对水泥砂浆微观结构的影响,采用核磁共振(NMR)设备和BRS-Ⅱ型脉冲孔渗测定仪测试了骨料分别为标准砂和机制砂(粒径分别为1.25~2.50 mm、2.50~5.00 mm、5.00~10.00 mm)的标准柱状水泥砂浆试件的T₂谱、核磁共振成像硬脉冲一维频率编码技术(GR序列)和渗透率,探究了骨料粒径对水泥砂浆试件孔径分布、渗透率、孔隙度、迂曲度、孔隙结构分形特征以及孔隙空间分布均匀程度的影响。研究结果表明:标准砂试件的等效平均孔隙半径及孔隙度最小,等效平均孔隙半径随骨料粒径的增大先减小后增大,而骨料粒径与迂曲度呈负相关关系,与渗透率、孔隙度以及毛细孔分形维数呈正相关关系。另外,随着骨料粒径增加,试件孔隙空间分布不均匀程度显著增大,骨料粒径对水泥砂浆孔隙空间分布影响明显。

关键词: 水泥砂浆, 微观结构, 骨料粒径, 渗透率, 迂曲度, 孔隙结构分形特征, 孔隙空间分布均匀程度

Abstract: In order to study the effect of aggregate particle size on the microstructure of cement mortar, the T₂ spectra, nuclear magnetic resonance (NMR) imaging hard pulse one-dimensional frequency coding technique (GR sequence) and permeability of standard cylindrical cement mortar samples with aggregates of standard sand and mechanized sand (particle sizes of 1.25~2.50 mm, 2.50~5.00 mm, and 5.00~10.00 mm, respectively) were measured by using a NMR device and the BRS-II impulse pore permeability detector. The effect of aggregate particle size on the pore size distribution, permeability, porosity, tortuosity, fractal characteristics of pore structure, and the uniformity of pore space distribution of cement mortar samples were investigated. The results show that the equivalent average pore radius and porosity of standard sand sample are the smallest. The equivalent average pore radius decreases first and then increases with the increase of aggregate particle size, while the aggregate particle size is negatively correlated with the tortuosity, and positively correlated with the permeability, porosity and fractal dimension of the capillary pores. In addition, with the increase of aggregate particle size, the unevenness of pore space distribution of sample increases significantly, and the aggregate particle size obviously affects the pore space distribution of cement mortar.

Key words: cement mortar, microstructure, aggregate particle size, permeability, tortuosity, fractal characteristic of pore structure, uniformity of pore space distribution

中图分类号:

TQ172

李贤, 宁麟, 陈亮亮, 李炀, 邓小江. 基于核磁共振技术分析骨料粒径对水泥砂浆微观结构的影响[J]. 硅酸盐通报, 2023, 42(12): 4216-4223.

LI Xian, NING Lin, CHEN Liangliang, LI Yang, DENG Xiaojiang. Study on Effect of Aggregate Particle Size on Microstructure of Cement Mortar Based on Nuclear Magnetic Resonance Technology[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(12): 4216-4223.

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