Relationship between the Size of the Samples and the Interpretation of the Mercury Intrusion Results of an Artificial Sandstone.

Hua Dong,Peng Gao,Yibing Zuo,Guang Ye,Hongzhi Zhang

doi:10.3390/ma11020201

Abstract

Mercury intrusion porosimetry (MIP) measurements are widely used to determine pore throat size distribution (PSD) curves of porous materials. The pore throat size of porous materials has been used to estimate their compressive strength and air permeability. However, the effect of sample size on the determined PSD curves is often overlooked. In pursuit of a better understanding of the effect of sample size on mercury intrusion into porous materials, a combined experimental and numerical approach was applied. Quartz sand and epoxy resin were mixed to form artificial sandstone. Digital microstructures of the sandstone were obtained by using X-ray computed tomography (CT scan) technique. PSD curves of the artificial sandstone with different sample sizes were determined both by MIP measurement and by simulation of mercury intrusion (i.e., MIP simulation). Percolation analysis was performed on mercury-intruded pores in the digital microstructures. The PSD curves determined both by MIP measurements and by MIP simulations show that there was a significant effect of sample size on mercury intrusion before percolation of mercury-intruded pores. The effect of sample size decreased with the increasing pressure. After the mercury-intruded pores percolated through the samples, the effect of sample size on mercury intrusion became minor. The pore throat size of the artificial sandstone was used to estimate the air permeability using the relation proposed in the literature. The calculated air permeability of the smaller sandstone sample was higher. However, in principle, the air permeability of sandstone samples should be independent of the sample size. Two main conclusions can be drawn: (1) a fixed sample size should be used in MIP measurements or MIP simulation so that the PSD curves of different samples can be properly compared, (2) sample size needs to be considered when the pore throat size determined by MIP measurement is used for estimating air permeability.

Highlights

The pore structure of porous materials has an important role in mechanical and transport properties [1]
Figure presents the curves of the samples with different sizes (S10-Exp and Figure determined by measurements were conducted on the large sample (S10-Exp), with determined by by Mercury intrusion porosimetry (MIP)
In principle, the air permeability of sandstone samples should be independent of the sample size

Summary

Introduction

The pore structure of porous materials (e.g., rocks and cement-based materials) has an important role in mechanical and transport properties [1]. The pore structure of porous material can be characterized by a number of parameters, including porosity, hydraulic radius, specific surface area, threshold diameter, and pore size distribution [2]. Materials 2018, 11, 201 porosimetry (MIP) is used to characterize the pore structure of porous materials for pore throat sizes from several nm to hundreds of μm [3,4,5]. The above techniques for characterizing pore structure have been comprehensively reviewed and compared in References [6,7,8]. The current study is limited to MIP technique for pore structure characterization

Objectives

Methods

Conclusion