Aim: To determine the strength characteristics of a rock using the point load test and visual judgement. Materials
Method (Standard, 2007)
1. Measure the dimensions of the rock which includes the diameter and length
2. Find the length to diameter ratio to determine which test will be used. If the ratio is greater than 1 use diametrical test. But if the ratio is between 0.6 and 1 use axial test
3. The axial test was carried out for this rock which is then placed in the loading device upright and closed the platens so they are aligned to the centre
4. Increase the load until failure and record the distance between the platens
5. Record the failure load and mode for the rock
Strength characteristic of a rock is an integral part in engineering and geotechnical practice as it can be the base of structure or the structure itself hence the point test was utilised to determine this crucial parameter. The rock is initially a round cylindrical shape that is intact. During the testing it split in a roughly 2:3 ratio vertically at the load of 21.373kN with the platen distance of 29mm. From the experimental data and calculations of the rock, the UCS has value is of more than 250MPa and the Is of 10.54MPa indicating that it is an extremely strong rock with grade R6 (Hudson & Harrison , 1997). This highlights that only the hammering of a geological hammer can put a dint in it, if it were to be tested in the field. Therefore the rock is an intact rock consisting of mainly both dark and light grey coarse grains as well as other minerals such as feldspar- white minerals, quartz- transparent and black minerals and mica- creamy white mineral which matches a description of an extremely strong intrusive granite. (Plummer, et al., 2012)
Overall determining the strength of a rock through point load test yields the important values such as UCS which was over 250Mpa and Is of 10.54MPa highlighting that the rock is extremely strong and combined with the visual inspection of grey coarse grained the conclusion is that the rock is a very strong granite.
Hudson, J. A. & Harrison , J. P., 1997. Engineering Rock Mechanics. 1st ed. Oxford: Elsevier Science Ltd.. Plummer, C. C., Carlson, D. H. & Hammersley, L., 2012. Physical geology. 14th ed. California: McGraw- Hill Higher Education. Standard, A., 2007. AS 4133.4.1 Methods of testing rock for engineering purposes, New South Wales: Standard Australia Limited.
1. Point load strength index (Is)
1.2 Core diameter of test rocks
1.3 Strength description of rock
1.4 Strength correlationa