Study on Effect of Aggregate Particle Size on Microstructure of Cement Mortar Based on Nuclear Magnetic Resonance Technology

Abstract

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

CLC Number:

TQ172

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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