Cerchar tests, Schimazek index and the drilling-rate index.
Assessment of drilling-equipment wear
escOrsa has specific laboratory equipment to assess the tensile strength and abrasiveness of the medium and to estimate feed and production rates to optimise time and material costs in open-pit and underground excavations.
Specific assays for rock abrasiveness and excavatability
Cerchar test equipment, the drilling-rate index (DRI) and the Schimazek index, among others, are used to assess the degree of hardness and abrasiveness of the rock.
Cerchar test kits directly measure rock hardness and abrasiveness. From a thin-section assessment, the percentage of quartz and other abrasive minerals in the sample is determined, and together with the grain size and tensile strength, the Schimazek index is obtained. These parameters are important for the assessment of headwear in drilling and excavation rigs.
One of the most complete drilling assays is the DRI. The DRI values of rock are correlated with the drilling speed for each particular hammer and drill diameter.
Some rocks do not maintain their properties when exposed to weathering agents
Once the excavation is open, the exposed rock may change, losing its initial strength characteristics, resulting in stability problems or causing problems in the material used in breakwaters and embankments. Durability assays can be performed to characterise the future behaviour of the material.
