Ms. Humby et al., DEVELOPMENT OF A FRIABILITY TEST FOR GRANULAR FILTER MEDIA, Journal of the Chartered Institution of Water and Environmental Management, 10(2), 1996, pp. 87-91
At present there is no generally accepted test available for character
izing the friability of granular filter media in the context of its ab
ility to withstand handling and placing, as distinct from abrasion res
istance during backwashing - which is the subject of other, existing,
test methods. Most existing procedures tend to be grinding tests and h
ave little meaning. The approach selected in this work was to adapt th
e ring shear test, in which a sample (large enough to be analysed by s
ieving) is subjected to shear under a known compression load and the c
hange in the undersize fraction is assessed. A representative selectio
n of dry media was submitted to the test and the results proved to be
reproducible and capable of distinguishing (clearly) between friable a
nd non-friable resistant types. The procedure is likely to become the
basis of a standard test.