Impacts of Abnormal Nanoindentation Points on Micromechanical Properties and Content of Phase in Hydrated Cement Paste

Abstract

During nanoindentation analysis of cementitious materials, data points with abnormal load-depth curves are often obtained. This study investigates the effect of these abnormal indentation points (AIP) on the micromechanical properties and content of phase in hydrated cement paste calculated by nanoindentation test combined with deconvolution analysis, including the least-square-estimation (LSE) and maximum-likelihood-estimation (MLE) methods. The results indicate that the AIP is mostly associated with phases with low mechanical properties, and the exclusion of AIP significantly affects the volume fractions of micropore phase and low-density calcium silicate hydrate, while the mechanical properties of phases keep stable except that the mechanical properties of micropore phase are slightly increased by the exclusion of the AIP. The phase contents derived based on LSE showed a more significant change than those derived based on the MLE when AIP was excluded from indentation data. In addition, the phase content derived by nanoindentation analysis was compared to that derived by other analysis methods, including mercury intrusion and quantitative x-ray diffraction.