Investigation into the appropriate laboratory testing procedures for the determination of the index properties of the Lateritic Soils of Western Ethiopia (Nedjo-Jarso-Begi Road area)
| dc.contributor.advisor | Haile, Mesele (PhD) | |
| dc.contributor.author | Million, Wossen | |
| dc.date.accessioned | 2018-06-21T08:10:07Z | |
| dc.date.accessioned | 2023-11-11T12:53:31Z | |
| dc.date.available | 2018-06-21T08:10:07Z | |
| dc.date.available | 2023-11-11T12:53:31Z | |
| dc.date.issued | 2009-11 | |
| dc.description.abstract | The appropriate laboratory testing procedures while carrying out index property tests of lateritic soils found in western Ethiopia (Nedjo, Jarso and Begi areas) have been investigated. Classification and composition of these soils have also been studied. The X-Ray Diffraction (XRD) analyses revealed that the soils in these areas are composed of minerals of Kaolinite and Smectite groups; such as Kaolinite, Quartz, Hematite, Vermiculite, Dickite, Borax, Illite, Nacrite. The X-Ray Fluorescent (XRF) analysis showed that there is a high concentration of sesquioxide minerals and there is no amorphous material present in the soils. Comparison between the moisture contents determined using air drying (or alternatively 50oC oven drying temperature) and that of 105oC oven drying temperatures indicates that there is no significant amount of structural water; however, comparing to the non-lateritic soils from Addis Ababa, the western Ethiopia lateritic soils have some amount of structural water or water of hydration. In the analysis of Atterberg Limits, in majority of the soils difference was observed between the Atterberg Limits obtained from test on a specimen mixed for 5min and that of 30min, this indicates that the cementation of the clay particles is to be disaggregated with higher mixing time. Analysis of specific gravities of the soils using various pretreatment and testing procedures showed that, increase in drying temperature from its in situ condition to an air-dried or equivalent of 50oC oven drying temperature and further to 105oC oven drying temperature reduces specific gravity of the soils. Analyses of the grain-size distributions (grading curves) with respect to the effects of different testing procedures (pre-test treatment methods), the effects of specific gravity variation within a sample, and the variation of sample location /depth/ and other physical properties indicated that the soils were not homogeneous within the laterite zone. The dry sample preparation and testing procedures tends to decrease the percentage of coarser particles as the coarser particles became highly fractured during the pulverization process. As a result these dry sieving techniques were found to be inappropriate. The analyses of the grading curves using mass proportion and the modified grading curve using volume proportion, which uses separate specific gravity, showed that the two grading curves are nearly the same; hence, the need of modifying the grading curves by volume proportion is not as such important especially when wet sieving method is used. Moreover, the analysis of grading curves with respect to sampling depth showed that, generally, the soils become coarser as the sampling depth increases. This confirms that the degree of weathering decreases with depth. Soil classification using Unified Soil Classification System (USCS), AASHTO Classification System, Wesley’s Classification Method (classification using mineralogical composition) and soil grouping using genetic basis and soil forming factors were analyzed. According to the USCS chart the soils under investigation falls in the MH zone, which means that the soils have ‘poor’ engineering properties that are considered unsuitable for various engineering purposes. However, in practice, such soils frequently have good engineering properties especially for construction of sub grades and embankments. Contrary to the USCS, the AASHTO Classification System classify majority of the soils under sub group A-2-7 with a group index less than 4, which mean the soils are good sub grades and embankments construction materials. Using the Wesley’s Classification Method the soils fall under Group C, sub-group (c). Soils under this group have good engineering properties. The soils under investigation have fallen under ferrisols group where erosion has kept pace with profile development. The analysis of the test results obtained from different laboratory testing procedures used for moisture content, plasticity tests, grain-size analysis and specific gravity tests for the lateritic soils found in Western Ethiopia has shown that the soils are sensitive to the type of testing procedures as a result an appropriate laboratory testing procedures attached in Appendix-A are proposed. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/12345678/2608 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | Soils ; Western ;Ethiopia | en_US |
| dc.title | Investigation into the appropriate laboratory testing procedures for the determination of the index properties of the Lateritic Soils of Western Ethiopia (Nedjo-Jarso-Begi Road area) | en_US |
| dc.type | Thesis | en_US |