The determination of uniaxial compressive strength from point load strength for pyroclastic rocks

• The uniaxial compressive strength–point load index relation was studied for pyroclastic rocks.
• Very strong exponential relations were found uniaxial compressive strength and point load index.
• The results were compared to the studies in the literature.

The point load test has often been reported as an indirect measure of compressive strength. It has been used widely in practice due to easy testing, the simplicity of specimen preparation, and possible field applications. Many researchers have investigated the relation between uniaxial compressive strength (UCS) and point load index (Is) for different rock types. However, there are limited studies in the literature for soft rocks such as pyroclastic rocks. In this study, the relation between UCS and Is was investigated for pyroclastic rocks having UCS values are less than 50 MPa. Very strong exponential relations were found for dry rocks, saturated rocks and both dry and saturated rocks. The results were also compared to the studies in the literature.