On Phase Identification of Hardened Cement Pastes by Combined Nanoindentation and Mercury Intrusion Method.

Jingwei Ying,Yijie Huang,Xiangxin Zhang,Zhijun Jiang

doi:10.3390/ma14123349

Abstract

The micro-mechanical properties of hardened cement paste can be obtained by nanoindentation. Phases at different locations can generally be determined by using the Gaussian mixture model (GMM) method and the K-means clustering (KM) method. However, there are differences between analysis methods. In this study, pore structure and porosity of hardened cement paste aged three, seven, and 28 days were obtained by mercury intrusion porosimetry (MIP), and their micro-mechanical properties were obtained by the nanoindentation method. A new method, GMM-MIP and KM-MIP, was proposed to determine the phase of hardened cement paste based on the pore structure and nanoindentation results. The results show that GMM-MIP and KM-MIP methods are more reasonable than GMM and KM methods in determining the phase of hardened cement paste. GMM-MIP can be used to obtain reasonable phase distribution. If the micro-mechanical properties of each phase in hardened cement paste do not satisfy the normal distribution, the GMM method has significant defects.

Highlights

Climate change is one of the most critical issues of our time
In order to study the macroscopic response of non-uniformly degraded hardened cement paste, Brow [1] used nanoindentation technology to obtain the elastic modulus of each indentation point and used the gauss convolution method to identify each phase component of hardened cement paste
The pore of hardened cement paste obtained by the mercury intrusion porosimetry (MIP)

Summary

Introduction

Climate change is one of the most critical issues of our time. there is still a long way to go to achieve the goal of the Paris Agreement. Cement-based composites are widely used in civil engineering. Hardened cement pastes can be regarded as composites consisting of phases with different mechanical properties on both micro and nanoscale. The composition and micro-mechanical properties of hardened cement paste influence concrete macro-mechanical properties and durability [1,2]. Nanoindentation technology can be used to obtain the mechanical properties of cement clinker and the micromechanical properties of hydration products and porosity. In order to study the macroscopic response of non-uniformly degraded hardened cement paste, Brow [1] used nanoindentation technology to obtain the elastic modulus of each indentation point and used the gauss convolution method to identify each phase component of hardened cement paste. The microstructure and micromechanical properties of hardened cement paste have an important influence on concrete engineering

Methods

Results

Conclusion