an engineering geological characterisation of tropical clays - GBV
an engineering geological characterisation of tropical clays - GBV
an engineering geological characterisation of tropical clays - GBV
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194<br />
A comparison <strong>of</strong> laboratory determined linear shrinkage values (LS measured) with those<br />
computed (LSLL) according to Equation (10.18) reveals a very strong closeness. The two sets<br />
<strong>of</strong> data are practically identical in terms <strong>of</strong> maximun <strong>an</strong>d minimum values, the r<strong>an</strong>ge as well<br />
as the medi<strong>an</strong>, mode <strong>an</strong>d me<strong>an</strong> values (Table 10.5). The two comparable st<strong>an</strong>dard deviations<br />
<strong>of</strong> 4,30 <strong>an</strong>d 4,02, <strong>an</strong>d very strong correlation <strong>of</strong> 0,93 are further evidence <strong>of</strong> the similarity <strong>of</strong><br />
the two sets <strong>of</strong> data; <strong>an</strong>d therefore the reliability <strong>of</strong> the new relationship in estimating linear<br />
shrinkage <strong>of</strong> soils from laboratory measured liquid limits. The relationship between laboratory<br />
measured <strong>an</strong>d calculated linear shrinkage values is illustrated diagrammatically in Fig. (10.8),<br />
<strong>an</strong>d takes the form <strong>of</strong><br />
LSmeasured = 0,997LSLL (10.19)<br />
LS measured/ LSLL<br />
Measured linear shrinkage<br />
LSmeas. (%)<br />
35<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
n = 90<br />
R 2 = 0,86<br />
LS meas. = 0,997LSLL<br />
Black <strong>clays</strong> <strong>an</strong>d red<br />
soils<br />
Linear (Black <strong>clays</strong><br />
<strong>an</strong>d red soils)<br />
0 10 20 30<br />
Calculated linear shrinkage LSLL<br />
(%)<br />
Figure 10.8. A correlation between calculated <strong>an</strong>d laboratory determined linear<br />
shrinkage <strong>of</strong> black <strong>clays</strong> <strong>an</strong>d red soils.<br />
10.4 Free swell <strong>an</strong>d other index properties<br />
The Swelling capability <strong>of</strong> black <strong>clays</strong> <strong>an</strong>d red soils could be estimated with a high degree <strong>of</strong><br />
approximation (R² = 0,85 <strong>an</strong>d over) from laboratory results <strong>of</strong> Atterberg limits <strong>an</strong>d linear<br />
shrinkage. The form <strong>an</strong>d strength <strong>of</strong> correlation between laboratory determined free swell<br />
(FS) on one h<strong>an</strong>d; <strong>an</strong>d liquid limits (LL), plasticity index (PI) <strong>an</strong>d linear shrinkage (LS) <strong>of</strong> the<br />
soils on the other, are illustrated in Table (10.6) <strong>an</strong>d Fig. (10.9).