The unconfined (or uniaxial) compressive strength (UCS) of a rock is a common measure of the strength of intact rock. It is normally measured on cylinders of rock core by compressing the core between two platens and measuring the maximum load at which failure occurs. The UCS is frequently used as one of the components in rock mass classification systems like the NGI- Q systems and the Geomechanics RMR systems. Two common methods of estimating UCS in the field are the field index test and the Point Load Strength Index. | 
