Testing procedure, measurement, calculations and classifications are given below.
This test is performed on rock to estimate its durability to weathering (mechanical disturbance and effect of water). For this test, about 500g of rock samples/pieces (each about 40-60g) are used. The slake durability index obtained for the second cycle is used to classify rock.
Test measurements and calculations from the test in this video are as follows:
Mass of empty drum (m4) 842.2 g
Mass of drum with rock sample (m1) 1285.5 g
Mass of drum with dried rock after 1st cycle (m2) 1244.6 g
Mass of drum with dried rock after 2nd cycle (m3) 1237.1 g
Calculations of slake durability index for 1st (Id1) and second (Id2) cycles:
Id1=(m2-m4)/(m1-m4)=(1244.6-842.2)/(1285.5-842.2)=402.4/443.3=0.907 or 90.7%
Id2=(m3-m4)/(m1-m4)=(1237.1-842.2)/(1285.5-842.2)=394.9/443.3=0.891 or 89.1%
Based on Id2, durability of this rock is 'Medium High' (see the table below).
Classification table based on slake durability index
Durability Id1 Id2
Very High 99-100 98-100
High 98-99 95-98
Medium High 95-98 85-95
Medium 85-95 60-85
Low 60-85 30-60
Very Low less than 60 0-30
Reference: Franklin, J. A., & Chandra, R. (1972, May). The slake-durability test. In International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (Vol. 9, No. 3, pp. 325-328). Pergamon.
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