an engineering geological characterisation of tropical clays - GBV

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The swelling capability in terms of free swell (FS) could be estimated from the Atterberg
limits and linear shrinkage and vice versa, using the relationships,
and
FS = 3,17(LL-45) (10.20)
FS = 3,79(PI-13) (10.21)
FS = 7,29(LS-7) (10.22)
Free swell/ other index properties
180
160
140
FS = 7,29(LS - 7)
R 2 = 0,85
n = 90
FS = 3,17(LL - 45)
R 2 = 0,92
Free swell FS (%)
120
100
80
60
FS = 3,79(PI - 13)
R 2 = 0,88
FS vs LL
FS vs PI
FS vs LS
40
20
0
0 20 40 60 80 100
Liquid limit LL, plasticity index PI and linear
shrinkage LS (%)
Figure 10.9. Correlation: laboratory measured values of free swell and laboratory
liquid limit, plasticity index and linear shrinkage of black clays and red soils.
The strength of agreement between laboratory measured free swell values (FS meas.) and those
calculated by computation from laboratory Atterberg limits(FSLL; FSPI) and linear shrinkage
(FSLS) using the above new relationships is very high (Table 10.6); as characterised by very
strong correlations of 0,92 and over. Further evidence in their closeness is revealed by the
median (126-131%), mode (125-131%), mean (118-123%) and standard deviation (31-34)
values which are found to be closely comparable and of the same order of magnitude.
The relationships between laboratory measured and calculated free swell values (Fig. 10.10)
take the form of
FSmeasured = 1,01FSLL (10.23)