Evaluating the Use of Rice Husk Ash for Soil Stabilisation to Enhance Sustainable Rural Transport Systems in Low-Income Countries

Ada Farai Shaba, Esdras Ngezahayo (), Goodson Masheka and Kajila Samuel Sakuhuka
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Ada Farai Shaba: School of Engineering, University of Zambia, Lusaka P.O. Box 32379, Zambia
Esdras Ngezahayo: School of Engineering, University of Birmingham, Birmingham B15 2TT, UK
Goodson Masheka: School of Engineering and Technology, Mulungushi University, Kabwe P.O Box 80415, Zambia
Kajila Samuel Sakuhuka: School of Engineering and Technology, Mulungushi University, Kabwe P.O Box 80415, Zambia

Sustainability, 2025, vol. 17, issue 15, 1-16

Abstract: Rural roads are critical for connecting isolated communities to essential services such as education and health and administrative services, as well as production and market opportunities in low-income countries. More than 70% of movements of people and goods in Sub-Saharan Africa are heavily reliant on rural transport systems, using both motorised but mainly alternative means of transport. However, rural roads often suffer from poor construction due to the use of low-strength, in situ soils and limited financial resources, leading to premature failures and subsequent traffic disruptions with significant economic losses. This study investigates the use of rice husk ash (RHA), a waste byproduct from rice production, as a sustainable supplement to Ordinary Portland Cement (OPC) for soil stabilisation in order to increase durability and sustainability of rural roads, hence limit recurrent maintenance needs and associated transport costs and challenges. To conduct this study, soil samples collected from Mulungushi, Zambia, were treated with combinations of 6–10% OPC and 10–15% RHA by weight. Laboratory tests measured maximum dry density (MDD), optimum moisture content (OMC), and California Bearing Ratio (CBR) values; the main parameters assessed to ensure the quality of road construction soils. Results showed that while the MDD did not change significantly and varied between 1505 kg/m 3 and 1519 kg/m 3 , the OMC increased hugely from 19.6% to as high as 26.2% after treatment with RHA. The CBR value improved significantly, with the 8% OPC + 10% RHA mixture achieving the highest resistance to deformation. These results suggest that RHA can enhance the durability and sustainability of rural roads and hence improve transport systems and subsequently improve socioeconomic factors in rural areas.

Keywords: rice husk ash; soil stabilisation; rural transport systems; sustainable transport infra-structure; low-income countries (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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