Performance of Roads Constructed on Black Cotton Subgrade Soil with Respect to Replacement Materials Type and Replacement Depth (A Case Study on Modjo - Edjere Road)
| dc.contributor.advisor | Gebregziabher, Efrem (Eng) | |
| dc.contributor.author | Yunus, Melik | |
| dc.date.accessioned | 2018-07-20T12:53:43Z | |
| dc.date.accessioned | 2023-11-11T12:53:56Z | |
| dc.date.available | 2018-07-20T12:53:43Z | |
| dc.date.available | 2023-11-11T12:53:56Z | |
| dc.date.issued | 2015-03 | |
| dc.description.abstract | The performance of roads depends mainly on the strength of the underlying subgrade soil. Black cotton soil gives rise to the failure of the road constructed on it. These soils have cyclic volume change due to fluctuation of moisture content. The degree of volume change or expansiveness depends on the mineralogical composition of the soil. Black cotton soil with montmorillonite is a dominating mineral and experiences high volume changes cause considerable failure to the structures constructed on it. The current study was conducted on modjo –edjere road project where subgrade soil is black clay soil. The road failed with in liability period showing longitudinal cracks on carriage way and shoulder of the road. This thesis was conducted to evaluate the adequacy of the replacement depth and replacement materials type made for the road. Accordingly, both disturbed and undisturbed soil samples were brought from the site for laboratory tests both for subgrade soil and replacement materials. Hence, swelling pressure and bulk density of the soil were determined from undisturbed subgrade soil samples. Cracked sections of the road stretch were selected and excavation was made to know the origin of the cracks. Hence, cracks were originated from subgrade soil and depths of cracks were measured for the selected sections of the road from natural ground level. Replacement depth was determined from measured swelling pressure and compared to the crack depth actually measured on the field. Accordingly, replacement depth of 60cm which was made for the road under study is insufficient to counter balance upward swelling pressure from native subgrade soil. Moreover, It was also seen that overburden pressure of the pavement structure is less than measured swelling pressures. Key Words: Road performance, Black Cotton Soil, Swelling Pressure, Replacement Depth, Replacement Materials Types | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/12345678/9606 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | Road performance; Black Cotton Soil; Swelling Pressure; Replacement Depth; Replacement Materials Types | en_US |
| dc.title | Performance of Roads Constructed on Black Cotton Subgrade Soil with Respect to Replacement Materials Type and Replacement Depth (A Case Study on Modjo - Edjere Road) | en_US |
| dc.type | Thesis | en_US |