In this article, we will study different rock mechanics equipment use for testing in the laboratory. Rock Mechanics labs are generally equipped with instruments to study rock behavior under different stress, strain configuration. We study the basics of different machines and their usage in our practical life.
List of Rock mechanics equipment in laboratory
- Robertson shear box
- Slake Durability Test Apparatus
- Rock Coring Machine
- Rock lapping machine
- Rock cutting machine
- Laboratory oven
- Abrasion machine
- Universal testing machine
- Portable ultrasonic non-destructive indicator tester
Slake Durability Test Apparatus
This test method is used for assessing the deterioration of rocks over a period of time when subjected to water immersion. The apparatus consists of a motorized drive unit mounted on a base plate and connected to two or four drums which rotate at a speed of 20 r.p.m.
The machine mounts a digital display for the visualization of the residual testing time. The tank assemblies are filled with water to a level 20 mm below the drum axis. The water level is indicated by a mark.
The test drums are manufactured from 2.00 mm mesh, 140 mm dia. x 100 mm long. Two drums are already included; while two additional ones can be ordered separately, see accessories.
The drums can be mounted/disassembled easily with the quick-release drive units.
Rock Coring Machine
This machine is specifically used in the laboratory for cutting core samples from hard materials such as rock and concrete. A clamp is provided to firmly secure the material during the cutting cycle.
The coring area is protected by a transparent cylinder. A special clamping device to prepare rock samples from core pieces is also available.
Rock lapping machine
Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine.
The term “lapping” is used to describe a number of various surface finishing operations where loose abrasive powders are used as the grinding agent at normally low speeds.
It is a process reserved for products that demand very tight tolerances of flatness, parallelism, thickness or finish.
Rock cutting machine
A rock cutting machine in the laboratory can be used to cut rock cores. Concrete cores, stones, building materials, and metallic specimens. A smooth finish cut can be made with the machine in either wet or dry operation according to the nature of the specimen (cutters are at extra cost).
The specimen cutting machine is designed to cut up to 200 mm (specify the size of deep cut required in the specimen) deep cut in the concrete, stones, tiles, soft rocks, and hard rocks, or any other similar material.
Laboratory ovens are ovens for high-forced volume thermal convection applications.
These ovens generally provide uniform temperatures throughout. Typical sizes are from one cubic foot to 0.9 cubic meters (32 cu ft) with temperatures that can be over 340 degrees Celsius.
The Los Angeles abrasion machine is used to measure the degradation of a mineral aggregate of standard gradings resulting from a combination of actions including abrasion or attrition, impact, and grinding in a rotating steel drum containing a specified number of steel spheres.
The test is widely used as an indicator of the relative quality of various sources of aggregate having similar mineral compositions.
Some other rock mechanics laboratory equipment used in rock testing
Robertson shear box
This apparatus was originally developed at Imperial College, London, by Professor E. Hoek. It is a simple and practical method of determining the strength and slope stability of rock, both in the field and in the laboratory.
The apparatus consists of a shear box designed to accept samples not larger than 115×125 mm or alternatively cores up to 102 mm dia. The shear box consists of two halves, the upper being connected to two rams for reversible shearing action and the lower connected to a ram for normal load application.
The loads are recorded by Bourdon tube load gauges or by pressure transducers.
The normal loading system is complete with an adjustable low friction pressure maintainer to absorb volume changes of the specimen during the shearing action and to ensure constant vertical stress.
Universal testing machine
A universal testing machine (UTM), also known as a universal tester, materials testing machine, or materials test frame, is used to test the tensile strength and compressive strength of rock material in the laboratory. An earlier name for a tensile testing machine is a tensiometer.
The “universal” part of the name reflects that it can perform many standard tensile and compression tests on materials, components, and structures.
The specimen is placed in the machine between the grips and an extensometer if required can automatically record the change in gauge length during the test. If an extensometer is not fitted, the machine itself can record the displacement between its crossheads on which the specimen is held.
However, this method not only records the change in length of the specimen but also all other extending / elastic components of the testing machine and its drive systems including any slipping of the specimen in the grips.
Once the machine is started it begins to apply an increasing load on the specimen. Throughout the tests the control system and its associated software record the load and extension or compression of the specimen.
Portable ultrasonic non-destructive indicator tester
Ultrasonic testing (UT) is a form of non-destructive testing (NDT) that uses high-frequency sound waves to measure the thickness or hardness of rock material in the laboratory.
Ultrasonic tests often are performed to assess corrosion on pipes, valves, and steel or aluminum constructions. An ultrasonic tester also is used to detect flaws such as cracks and leaks.
Thus, an ultrasonic tester is an integral tool used in material testing and engineering, manufacturing quality control, equipment condition monitoring, building and bridge inspection, and more.
Have a look at geotechnical lab equipment.