A lump sample (14-10mm) is mounted in resin and pushed against a rotating lap for a period of 500 revolutions with a force of 2kg. The percentage of the original sample weight is the AAV. This test gives an insight into mineral cleavage behaviour and intergranular bond strengths.
This test is a variation of the ACV where a load specific to the force required to produce 10% fines is investigated where fines are -2360m. The standard range into which the undersize should fall is 7.5% to 12.5%. The force to produce 10% fines is given by:-
Where x if the maximum force in KN […]
A sample of 2 kg is subjected to a continuous compressive force with a total load of 400kN. The rate of loading is 40kN per minute. As with the AIV the percentage passing 2360m is calculated. With both the AIV and ACV a lower value indicates a “stronger” rock.
The AIV was incorporated into the British Standards in 1955 as a measure of crushed rock strength. A sample of lumps (14-10mm) is impacted with a piston fifteen times and the product is sieved using a 2360m aperture. The percentage material passing denotes the AIV. The test is then repeated and should be within a […]
The British aggregate industry has a set of standard tests that are used to characterise the physical properties of aggregate products.
This technique was also adapted from the ceramics and hard metals industry by Middlemiss and King [1994]. A range of parameters can be obtained from this procedure including fracture toughness, crack length, crack density and extent of cracking. The procedure involves making an indentation into the test piece with a micro-hardness tester. The image of […]
This method is limited to very soft or very hard rocks [ISRM Brown (Ed) 1981]. The principle of the test is the determination of the amount of energy absorbed into a rock when impacted upon by a set amount of energy (0.74Nm). The orientation of the hammer is critical because values can be affected if […]
This device has been developed at the Utah Comminution Centre [Bourgeois 1992] and has proved to be very successful in recording impact fractures of particulate material. It allows the generation of force time histories when a particle is subjected to an impact. Dropping a steel ball of known mass and diameter from a known height […]
The HPB consists of a steel bar (1.2m length) which has a rock sample attached to it. A second bar (6.4m length) is then used to impact the sample. An optical sensor is then used to calculate the speed of the impact bar at the moment of impact. Two strain gauges at either end of […]
Although there are a number of methods of administering an impact the underlying principals are similar, namely that by varying the input energy of the impacting body and the size of the test sample it is possible to build a complex input energy to product size relationship. The results of the test allow the calculation […]