Utilization of Local Available Materials to Stabilize Native Soil (Earth Roads) in Tanzania—Case Study Ngara

Fikiri Fredrick Magafu, Wu Li

.

DOI: 10.4236/eng.2010.27068                

Abstract

The native soil behavior of unpaved low volume roads and their mode of failure were studied to establish proper method of stabilizing native soils using local available materials. The use of lime and its positive effect to modify and stabilize Ngara soil in Tanzania is presented in this paper. There are many methods of stabilizing soil to gain required engineering specifications. These methods range from mechanical to chemical stabilization. Most of these methods are relatively expensive to be implemeted by slowly developing nations and the best way is to use locally available materials with relatively cheap costs affordable by their internal funds. Tanzania is a country having abundantly amount of Lime. Ngara native soil roads (unpaved rural roads) was studied under preliminary investigation and found to have higher plasticity, tendency of swelling and shrinking, low bearing capacity when wet, compressive strength of soil to have higher sensitivity to moisture and lower shear strength when wet. These soil behaviors deny road access to about 32 million people in Tanzania (80% of population) during rainy season. The detailed investigations is still going on at China university of Geosciences but other results from similar researches show that Ngara soils can be stabilized by lime and gain the required engineering properties.

Keywords

Low Volume Roads, Higher Plasticity Index, Bearing Capacity, Shear Strength of Soil, Engineering Specifications, Swell and Shrinkage

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Road Fund Board of Tanzania. http://www.roadfund. org.tz
[2]	Tanzania National website. http://www.tanzania.go.tz.
[3]	SADC, “Guideline on Low Volume Sealed Roads,” 2003.
[4]	Ngara, “District Council Authority–Works Department,” 2008. http://www.ngaradc.com.
[5]	AASHTO, “The AASHTO Road Test: Pavement Re-search,” ERB special Report 61E, American Association of State and Highway Officials, Washington, 1962.
[6]	J. M. Johnsen and P. K. Senstad, “Effects of Tire Pres-sures on the Flexible Pavement Structure – A Literature Survey,” Norwegian Road Research Laboratory, Oslo, No. 62, 1992.
[7]	National Lime Association, “Lime Treated Soil Con-struction Manual: Lime Stabilization & Lime Modifica-tion,” 2004. http://www.lime.org/AMDTP.pdf
[8]	N. Little Dallas, “Evaluation of Structural Properties of Lime Stabilized Soils and Aggregates,” 2000.