Journal of Environment and Earth Science ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol 2, No.6, 2012
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Eberemu (2007). It implies that the initial degree of saturation must be carefully controlled when compacting soils
Reliability Index
3 2.6 BSH 2.2
WAS BSL
1.8 1.4 1 10
20
30
40
50
60
70
80
90
100
Coefficient of variation (%)
Fig.3: Variation of reliability index with coefficient of variation for degree of saturation
for use as covers and liners in waste containment facilities. 4.4 Effect of Bagasse Ash Content on Reliability Index The effect of bagasse ash content on safety index as the coefficient of variation is varied is shown in Fig.4. Bagasse ash content varied non-linearly as the coefficient of variation increased from 10-100%, reliability or safety index decreased significantly especially in the 60- 100% range of COV values. Generally higher compactions energies produced higher safety indices. As COV increased from 10-100%, β value correspondingly decreased in the ranges 2.667-1.715, 2.724-1.841 and 2.778-1.889 for BSL, WAS and BSH compactions, respectively. The rapid change in safety index as COV is varied from 10-100% is an indication that hydraulic conductivity is significantly influenced by changes in bagasse ash content contrary to the finding of Stephen (2007). Therefore, when compacting bagassefoundry sand mixtures for use in covers and liners in waste containment facilities the bagasse ash content must be strictly controlled.
Reliability Index (β)
3 2.6 BSH 2.2
WAS BSL
1.8 1.4 10
20
30
40
50
60
70
80
90
100
Coefficient of variation (%)
Fig.4: Variation of reliability index with coefficient of variation for bagasse ash content 4.5 Effect of Percentage Fines on Reliability Index The effect of percentage fines on the safety index as the coefficient of variation is varied is shown in Fig.5. Percentage fines produced a linear relationship as the coefficient of variation increased in the range in the range 10-
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