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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Alternatively, percentage swelling <strong>of</strong> <strong>clays</strong> could be derived by expressing the swelling (S<br />
mm) which occurs under <strong>an</strong>y load decrement (P kPa) as a percentage <strong>of</strong> the initial thickness<br />
(Ho mm) <strong>of</strong> test specimen. Complete results <strong>of</strong> percentage swelling calculated for tested black<br />
clay samples using this second method are given in Appendix C. A more summarised<br />
representation <strong>of</strong> the results for the samples is given in Table (7.23). A derived classification<br />
<strong>of</strong> relative degree <strong>of</strong> swelling <strong>of</strong> black <strong>clays</strong> based on this new method is also given in Table<br />
(7.24).<br />
Table 7.23. Percentage swelling <strong>of</strong> black <strong>clays</strong> under various load decrements (S% is in<br />
relation to initial specimen height, Ho, i.e. 2 nd method).<br />
Sample No. P (kPa) SP = Pmax (kPa) P (%) S (mm) Smax (mm) S (%) Smax(%)<br />
82,46 100 0,000 0,00<br />
41,23 50 0,106 0,96<br />
SA2-70cm 19,99 24 0,253 2,30<br />
10,00 82,46 12 0,321 1,036 2,92 9,42<br />
5,00 6 0,539 4,90<br />
2,50 3 0,725 6,59<br />
0,00 0 1,036 9,42<br />
37,48 100 0,000 0,00<br />
18,74 50 0,054 0,49<br />
SB1-70cm 10,00 37,48 27 0,126 0,425 1,15 3,86<br />
5,00 13 0,197 1,79<br />
2,50 7 0,279 2,54<br />
0,00 0 0,425 3,86<br />
36,23 100 0 0,00<br />
17,49 48 0,066 0,60<br />
SC25/50cm 8,75 36,23 24 0,16 0,475 1,45 4,32<br />
5,00 14 0,26 2,36<br />
2,50 7 0,347 3,15<br />
0,00 0 0,475 4,32<br />
44,98 100 0 0,00<br />
22,49 50 0,061 0,55<br />
SC29-50cm 11,24 44,98 25 0,149 0,493 1,35 4,48<br />
5,00 11 0,266 2,42<br />
2,50 6 0,356 3,24<br />
0,00 0 0,493 4,48<br />
Average 50,29 0,607 5,52<br />
Table 7.24. Classification <strong>of</strong> relative degree <strong>of</strong> swelling <strong>of</strong> black <strong>clays</strong> based<br />
on percentage swelling derived using the new/ 2 nd method (author, 2003).<br />
P (kPa) P (%) S (%) Swelling degree<br />
< 2,5 < 5 > 5 high<br />
2,5-7,5 5-15 5 – 2,5 moderate<br />
7,5-25,0 15-50 2,5- 0,5 low<br />
> 25,0 > 50 < 0,5 very low