The Effect of Using Desert Sands and Cement to Stabilize the Base Course Layer of Roads in Libya
This paper investigates using a mixture of natural sand, Portland cement, and manufactured aggregates to stabilize the base course layer for low-volume roads. Compaction and resistance to deformation California Bearing Ratio (CBR) results are measured and guidelines provided with consideration for hot desert areas like Libya. These tests have been conducted to provide relevant statistical conclusions and recommendations as to how much round-shaped sand may be used versus manufactured crushed sand for various traffic loads. In the last 15–20 years, Libya, along with many other developing countries in the area, has undergone a sizeable move towards modernization, including upgrading the road infrastructure that services the growing population. Such a project runs into challenges in areas with lower population density, that require that roadwork projects be kept under sharp cost constraints. Using a mixture of sand cement to stabilize the base course has been common for decades because the properties of cement improve the characteristics of natural sand; furthermore, when the road is built in a sandy desert, the use of desert sand is an obvious solution to containing costs. Nonetheless, natural sands have been rounded by years of mechanical action by environmental forces, and are therefore rounder and more prone to shifting than angular manufactured sand. Manufactured aggregates need to be imported from elsewhere in the country and so have higher costs and environmental considerations, both of which give these projects incentives to use the local desert sand. This paper only considers the use of manufactured aggregate of 0–5 mm in the base course and examines how using local desert sand in the aggregate mix can reduce costs. This solution brings with it many problems because, due to natural sand’s lower inherent stability with regards to manufactured sand, the road surface will degrade faster. The solution to this problem, presented here, is to relocate some of the strength of the road from the surface layer to the base course layer. This is done by reducing the thickness of the asphalt course to a minimum, and introducing more structural strength in the base course layer by means of a cement-stabilized base layer.
KeywordsSand Cement CBR Compaction Stabilization
The first author would like to thank the Department of Civil Engineering at École de Technologie Supérieure (ETS), for providing all the facilities to carry out the experiments. He wishes to thank the Ministry of Higher Education in Libya for support during his Ph.D. program.
- Al-Aghbari, M.Y., Dutta, R.K.: Suitability of desert sand cement mixes for base courses in highway pavements. Electron. J. Geotech. Eng. 10(4) (2005)Google Scholar
- Almadwi, F.S., Assaf, G.J.: Performance testing of paving mixes for libya’s hot and arid conditions, using marshall stability and SUPERPAVE gyratory compactor methods. In: International Congress and Exhibition Sustainable Civil Infrastructures: Innovative Infrastructure Geotechnology, pp. 313–323. Springer, Cham (2017)Google Scholar
- Ansi, B.: ASTM D698-test methods for moisture-density relations of soils and soil-aggregate mixtures. Method A (Standard Proctor)Google Scholar
- Azadegan, O., Yaghoubi, E., Li, J.: Effect of surface layer thickness on the performance of lime and cement treated aggregate surfaced roads. Electron. J. Geotech. Eng. 18, 1081–1094 (2013)Google Scholar
- Das, B.M.: Chemical and mechanical stabilization. Transportation Research Board (2003)Google Scholar
- Ismaiel, H.A.H.: Treatment and improvement of the geotechnical properties of different soft fine-grained soils using chemical stabilization. Shaker (2006)Google Scholar
- Patel, M.A., Patel, H.S.: A review on effects of stabilizing agents for stabilization of weak soil. Civ. Environ. Res. 2(6), 1–7 (2012)Google Scholar
- Sabbagh, A.O.: Design and viscoelastoplastic characterization of a lime-dune sand-asphalt mix (replacing aggregate, material laws, creep compliance, rutting) (1986)Google Scholar