Empirical Correlation of Uniaxial Compressive Strength and Primary Wave Velocity of Malaysian Granites Goh Thian Lai Doctor, School of Environment and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. e-mail: gdsbgoh@gmail.com Abdul Ghani Rafek Professor, School of Environment and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. e-mail: aghani@ukm.my Ailie Sofyiana Serasa Student, Petroleum Engineering Department, Faculty of Engineering, Technology & Built Environment (FETBE), UCSI University, Kuala Lumpur, Malaysia e-mail: ailie.serasa@gmail.com Norbert Simon Doctor, School of Environment and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. e-mail: norbsn@yahoo.com Lee Khai Ern Doctor, Institute for Environment and Development (LESTARI), National University of Malaysia, 43600 UKM Bangi, Selangor D. E., Malaysia e-mail: khaiernlee@ukm.my ABSTRACT Uniaxial compressive strength (UCS) plays a significant role in influencing the stability of structures such as cut slopes and excavation in rock masses. The rock material parameter of UCS also serves as an input parameter for geomechanical modeling in fracture basement studies. However, uniaxial compressive strength test (UCT), requires sample preparation, together with expensive and destructive laboratory testing and thus the limited rock samples has becomes a disadvantage. This article presents an inexpensive laboratory method for estimating the UCS values for Malaysian granites through means of non-destructive ultrasonic test. A total of 77 ultrasonic tests and uniaxial compressive strength tests were conducted to establish an empirical correlation of UCS and primary wave velocity (V p ). The empirical correlation of UCS and V p for granite was UCS = (2.55 x 10 -5 ) ∙ V p 1.7658 with a coefficient of determination (R 2 ) of 0.90. This new correlation offers a simple and fast method in estimation of uniaxial compressive strength of Malaysian granites, through measuring the ultrasonic transit time of rock samples in the laboratory. KEYWORDS: Granite, uniaxial compressive strength, primary wave velocity. - 1063 -