Compression Tackiness Tester

Another simplification would be to use fewer sections, say between 5 and 10, the length-to-diameter ratio L/D could be just 2 and the mould could be made of a material which is easier to machine like brass or aluminium alloy. 

This is a simple version of the uniaxial compression test, first developed by Colgate-Palmolive25 but now used by other industries. The procedure described below is based on an article by Monick25 but with slight modifications, as practised at one large chemical company. 

The method is an analogue of measuring tackiness of a powder by squeezing it by hand and observing if the mass breaks apart readily or else remains as a lump. 

When testing a sample of powder, the mould is placed on the base of the stand, with the two halves clamped together, the 

If the cylindrical briquette of powder does not collapse under the weight of one disk, add another in (6 mm) Micarta disk, then the in (13 mm) disk, and if the briquette still stands after 30 seconds, add the weight of the plunger too. In 30-second intervals, add weights on top of the plunger in half-pound (227 g) increments until the briquette collapses and note the total load at failure. 

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In addition to the five fundamental powder properties, there is a whole host of relative properties which usually represent a reading from a particular instrument and which are used as fingerprinting of a particular product to detect a change in its handling properties. A good example is the Compression Tackiness Tester... 

Note that a portable tester based on the same principle as the compression tackiness tester is defined by a British Standard for testing of soils16. It uses a split mould 38 mm in diameter and 76 mm long (note the 2 1 ratio), with the sample of soil extruded into it from a sampling tube. The load is applied manually by a rotary handle and a lead screw, through a calibrated spring. 

Comments on the Compression Tackiness Tester This is clearly a fingerprinting method of a proven practical value. The result does not represent, however, the unconfined yield stress corresponding to the compression load because the compression stress varies within the height of the briquette. This is because the load during the sample compression is partly taken up by wall friction and the stress (and the bulk density) therefore reduces in... 

The paper does not describe the sample preparation in much detail but it appears that the test mould is a split cell like the one used with the Compression Tackiness Tester except that the L/D ratio is always equal to two. The mould is not split into section horizontally like the one used by Williams et al,24 and the material is reported to be filled in the mould in three layers. Three different... 

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