Statistical Characteristics of Microhardness of Hardened Cement Paste

• Published in: Journal of Wuhan University of Technology. Materials science edition Vol. 33; no. 4; pp. 924 - 931
• Main Authors: Dang, Yudong, Shi, Xianming, Qian, Jueshi, Jiang, Yan, Li, Xincheng
• Format: Journal Article
• Language: English
• Published: Wuhan Wuhan University of Technology 01.08.2018; Springer Nature B.V
• Subjects: Cement; Cement paste; Cementitious Materials; Cements; Chemistry and Materials Science; Confidence intervals; Diamond pyramid hardness; Indentation; Materials Science; Probability density functions; Statistical analysis; microhardness; statistics analysis; distribution; hardened cement pastes
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/s11595-018-1914-9

Due to the intrinsic nature of a heterogeneous and anisotropic microstructure of cement based materials and the small indentation size, the measured microhardness values are subject to considerable variability. This work presents an in-depth assessment of microhardness of hardened cement pastes (HCPs) from a statistical perspective. Hundreds of microhardness measurements were conducted on an HCP sample using a Vickers Microhardness Tester. The results showed that the microhardness measured from the HCP sample significantly scattered with a large standard deviation, varying from tens to hundreds. The data-set of microhardness values was not normally distributed but fit best with a three-parameter lognormal model. By using a statistical software, the probability density function of the microhardness distribution can be readily obtained. The arithmetic mean and its 95% confidence intervals of the measured microhardness values can be used to best represent the microhardness characteristics of HCPs.