Vol. 1 No. 1 (2026)
Low-Volume Road Design Using Laterite and Stabilised Soils in South Sudan's Equatoria Region
DOI: 10.5281/zenodo.19205880
Published: March 26, 2026
Abstract
Low-volume roads constitute over 85% of South Sudan's rural road network and are the primary means by which farming communities in the Equatoria Region access markets, healthcare, and educational institutions. Despite their importance, these roads are largely constructed without reference to engineering design standards, using locally available laterite and gravelly soils whose suitability and geotechnical behaviour under tropical loading conditions are poorly characterised in the published literature for this specific geographic context. This study presents a comprehensive geotechnical and pavement engineering investigation of laterite and stabilised soils from three borrow areas in Central, Eastern, and Western Equatoria States, aimed at developing practical design guidelines for low-volume road construction using local materials. Forty-two soil samples were collected and subjected to physical, mechanical, and chemical characterisation, including particle size distribution, Atterberg limits, compaction, California Bearing Ratio (CBR) at 0, 7, 28, and 90-day curing intervals, X-Ray Fluorescence (XRF) geochemical analysis, and free swell. Stabilisation trials were conducted with hydrated lime (2–8%), ordinary Portland cement (2–8%), and rice husk ash (2–8%) to evaluate improvement in CBR and plasticity reduction. Accelerated loading trials at a field wheel-track facility assessed rutting performance over a simulated 3,000 × 10³ ESAL loading history. Results indicate that natural laterites from Equatoria meet the minimum CBR threshold for unsealed base course (CBR ≥ 80%) in two of three borrow areas after moisture conditioning, but all three require stabilisation to serve as a structural subbase above weak subgrade soils. Cement stabilisation at 4–6% produces the highest
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How to Cite
(2026). Low-Volume Road Design Using Laterite and Stabilised Soils in South Sudan's Equatoria Region. African Geotechnical Engineering, Vol. 1 No. 1 (2026). https://doi.org/10.5281/zenodo.19205880
Keywords
lateritelow-volume roadsoil stabilisationlimecementrice husk ashSouth SudanEquatoria
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Vol. 1 No. 1 (2026)
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African Geotechnical Engineering
References
- Unknown Author (2020). ENGINEERING PROPERTIES OF LATERITIC SOIL IN
- Research, 2(1). https://doi.org/10.37703/ajoeer.org.ng/q12021/06 K W Lee; A S
- Marcus; C-P Hu; K Acciaioli (1994). ESTIMATION OF LAYER COEFFICIENTS OF
- (2017). Study on flexural strength, modulus, and fatigue cracking of cementitiously stabilised
- https://doi.org/10.1080/14680629.2017.1325772 Unknown Author (2002). Appendix A
- https://doi.org/10.1680/rftimamocps.31838.0021 Unknown Author (1969). Works on
- Soil Mechanics and Foundation Engineering published in 1968. Soil Mechanics and
- Foundation Engineering, 6(2), 146-149. https://doi.org/10.1007/bf01704417 Guo,
- Runhua; Prozzi, Jorge A. (2009). Prediction of In-Service Fatigue Life of Flexible Pavements
- https://doi.org/10.1520/jte000338 Kelvin F. Ofori; Sophia Antoniello; Marcia English;
- Alberta N. A. Aryee (2022). Improving nutrition through biofortification–A systematic
- https://doi.org/10.3389/fnut.2022.1043655 Unknown Author (1976). Laterite Soil
- Engineering. https://doi.org/10.1016/b978-0-444-41283-6.x5001-1 Freitag, D. R.;
- Anderson, Duwayne M. (1975). Soil Stabilisation: Principles and Practices. Soil Science
- https://doi.org/10.2136/sssaj1975.03615995003900010002x ME, Yuga; J, Wani
- (2022). Soil Fertility and Farming Systems Assessment in Productive Areas of Western,
- (02). https://doi.org/10.51737/2766-4600.2022.038 Little, Dallas N. (1996).
- -23. https://doi.org/10.1177/0361198196154600102 Nugroho, Saiful Arif; Utami,
- Hayu Tyas; Prihantoro, Hanung Budi; Putero, Susetyo Hario (2011). ICONE19-44190
- (ICONE), 2011.19(0), _ICONE1944-_ICONE1944.
- https://doi.org/10.1299/jsmeicone.2011.19._icone1944_60 Unknown Author (2022).
- https://doi.org/10.1108/oxan-es272434 Unknown Author (2023). Crisis in Sudan:
- https://doi.org/10.19088/sshap.2023.022 Unknown Author (1975). Deformation
- https://doi.org/10.1016/0148-9062(75)91799-4 Chebet, F.C.; Kalumba, D. (2015).
- https://doi.org/10.1680/ecsmge.60678.vol3.200 Netterberg, F. (1994). Low-cost local
- https://doi.org/10.1007/bf00425935 Ola, Samuel Akinlabi (1982). Geotechnical
- https://doi.org/10.1016/0013-7952(82)90002-3 Chandrasekhar, Sathy; Pramada, P.
- N. (2006). Rice husk ash as an adsorbent for methylene blue—effect of ashing temperature.
- Adsorption, 12(1), 27-43. https://doi.org/10.1007/s10450-006-0136-1 Stojadinovic, S.
- (1989). The use of uniform sand for road construction. Unbound Aggregates in Roads, 380-
- https://doi.org/10.1016/b978-0-408-04355-7.50052-2 Unknown Author (2018).
- https://doi.org/10.22617/tim179140-2 Unknown Author (1998). Design and
- https://doi.org/10.1002/9780470935231.ch6 Maria Teresa de Nóbrega (1995).
- experimental. https://doi.org/10.11606/t.44.1995.tde-16112015-133834 Yoobanpot,
- Naphol; Jamsawang, Pitthaya; Horpibulsuk, Suksun (2017). Strength behavior and
- residue. Applied Clay Science, 141, 146-156. https://doi.org/10.1016/j.clay.2017.02.028
- Mortala Boye (2022). Reversing Years for Global Food Security: A Review of the Food
- Research and Public Health, 19(22), 14836-14836. https://doi.org/10.3390/ijerph192214836
- Unknown Author (2025). Geotechnical Engineering: Reviewers 2024. Proceedings of
- https://doi.org/10.1680/jgeen.2025.178.2.272 OECD (2022). OECD-FAO Agricultural
- Outlook 2022-2031. OECD agricultural outlook .../OECD-FAO agricultural outlook.
- https://doi.org/10.1787/f1b0b29c-en Amesh A. Adalja; Tom Inglesby (2022). A Novel
- https://doi.org/10.7326/m22-1581 Julia Marshall (1998). NIST calibration services
- users guide 1998. https://doi.org/10.6028/nist.sp.250e1998 Peter Schmitz; Anthony K
- Cooper; G. R. Quick (2002). Using satellite imagery for crime mapping in South Africa.
- ad08d002/content Bankole, Felix O.; Bankole, Omolola O.; Brown, Irwin (2011).
- SYSTEMS IN DEVELOPING COUNTRIES, 47(1), 1-23. https://doi.org/10.1002/j.1681-
- tb00330.x Peter Meyns (1998). Die "Entwicklungsgemeinschaft des
- Übersee, 31(2), 171-195. https://doi.org/10.5771/0506-7286-1998-2-171 Rebecca L.
- Siegel; Kimberly D. Miller; Nikita Sandeep Wagle; Ahmedin Jemal (2023). Cancer statistics,
- CA A Cancer Journal for Clinicians, 73(1), 17-48. https://doi.org/10.3322/caac.21763