EFFECT OF ROCK SURFACE ROUGHNESS ON SCHMIDT HARDNESS MEASUREMENTS

Determination of hardness with Schmidt Hammer is an interdisciplinary experimental method used by mining, geology and civil engineers. Surface roughness is an important parameter affecting the Schmidt hardness. In this study, hardness measurements were made on natural, grinded out and cut surfaces and on core samples and their results were compared. Furthermore, roughness properties of each surface were determined and their relations with hardness values were investigated. The highest hardness values and the lowest standard deviations were obtained from cut surfaces, while the lowest hardness values and the highest standard deviations were taken from natural surfaces. In this study, as the surface roughness decreases, hardness values were seen to increase and standard deviation values were found to decrease. As a result, the roughness of the surface where the Schmidt Hammer is applied should be eliminated and the test surface should be reevaluated if the standard deviation is high. © 2020 Union of Chambers of Engineers and Architects of Turkey. All rights reserved.