Effect of grain size or anisotropy on the correlation between uniaxial compressive strength and Schmidt hammer test for building stones. (13th September 2021)

• Record Type: Journal Article
• Authors: Kong, Fanmeng; Xue, Yiguo; Qiu, Daohong; Gong, Huimin; Ning, Zexu
• Is Part Of: Construction & building materials. Volume 299(2021)
• Publication Date: 2021-09-13
• Subjects: Grain size -- Anisotropy -- Correlation -- Uniaxial compressive strength -- Schmidt hammer test; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123941
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Coarse grain size causes discreteness of UCS and Schmidt hammer rebound number- R . UCS data rather than R responds to the anisotropy orientation sensitively. Correlated degree between UCS and R decline as varying grain size or anisotropy. Relative errors of estimated UCS increase as coarse grain or varying anisotropy. Ignoring grain size or anisotropy can yield unacceptable error for estimating UCS. Abstract: To provide guidance for using Schmidt hammer rebound number (N-type hammer: R N ) to predict uniaxial compressive strength (UCS) of heterogeneous building stones, this paper using sandstone (with fine or coarse grain size) and gneiss (with 0°, 45°, 90° inclined anisotropy) respectively explored the effect of grain size or anisotropy on the correlations of UCS- R N . Based on the regression analysis, no significant formula of UCS- R N can be developed for samples with vertical anisotropy. The results show that coarse grain size or 45° inclined anisotropy results in increasing discreteness of UCS and R N data. Then, grain size variation or multidirectional anisotropy deteriorates the statistical performance of equations between UCS and R N . Finally, the accuracy of estimated UCS through R N declines significantly due to the varying grain size or anisotropy orientation. Using the empirical equations ignoring grain size or anisotropy can yield unacceptable error for calculating UCS through R N . The present finding, thus, implies that the Schmidt hammer test should be performed on building stones with single grain size magnitude or unidirectional anisotropy. Also, the Schmidt hammer test parallel to the anisotropy should be used with much care for predicting UCS as no significant correlation.