Uniaxial compression test of rocks: Review of strain measuring instruments

The importance of uniaxial compression test (UCT) of rocks will never be overemphasized as it plays a vital role in understanding the mechanical properties of rocks for use in civil, mining, and petroleum engineering. Strain response of rocks to external loading is small; it requires a precise instrument to capture the strain with reasonable accuracy. The conventional method is associated with system compliance error, limited precision, and bedding error. Several methods were devised to alleviate these errors. This study embodies the existing strain measuring instruments during UCT of rocks, their principles, features, accuracy, merits, and demerits are correctly scrutinized. The paper serves as a powerful tool that enables the selection of a suitable instrument accordingly. It is hoped that the study will encourage more exploration in the area.