Effects Of Locust Bean (Parkia Biglobosa) Pod Extract on The Consistency Limits of Marginal Soils for Road Pavement Layer Construction

Keywords: Locust bean pod extract, liquid limit, plasticity index, consistency index, chemical stabilization

Abstract

Earthworks in road pavement layer construction present huge challenges with severe financial implications especially when suitable material for base course and subbase course are not found along the road corridor or within reasonable haulage distances. In most cases, it may be easy to find marginal materials or materials that need some form of stabilization. Chemical and mechanical stabilization is common but could be expensive. Plant extracts for stabilization hold promise but more research is required to identify locally available plants that can be cultivated or applied at scale if found useful. In this exploratory study, the potential effects of stabilization of marginal lateritic gravel soils using locust bean pod extract (LBPE) were studied for Consistency Limits of natural gravel materials for road pavement layer construction. The extract was prepared by pounding and soaking the locust bean pods in tap water for intervals of up to 28 days. The soil sample was obtained from Agyei-Ano South, Sunyani, and tested in the geotechnical laboratory of Sunyani Technical University (STU). The soil was analyzed for index properties and classified as Silt-Clay material (A-6(5)) and clayey gravels (GC) using the AASHTO and Unified Soil Classification Systems respectively. Consistency limit tests for the control and test specimens were determined using distilled water and LBPE respectively. The soils stabilized with LBPE were found to generally exhibit 3.5% – 7.1% higher Liquid Limit (LL), and 0.9% – 15.0% higher Plastic Limit (PL) than the control. Compared with the control, the Plasticity Index (PI) values were lower by up to 22%. Lower PI is desirable in road construction materials. Improvements of up to 20.2% in the Consistency Index and up to 55 % in the liquidity index of the LBPE samples over the control were observed. This is an indication that LBPE could improve the engineering properties and change the classification of the lateritic soil, in this instance, from G30 grading envelope plasticity index requirement to the G40 grading envelope plasticity index requirement. The optimum soaking duration was found to be 3 days.

Author Biographies

Joshua Jacob Vordoagu, Kwame Nkrumah University of Science and Technology

Ing. Joshua Jacob Vordoagu is a geotechnical engineer and infrastructure expert, and lecturer at the Civil Engineering Department of Sunyani Technical University, Sunyani, Ghana and a PhD student at the Regional Transport Research and Education Centre Kumasi (TRECK) at the College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. He is a registered professional engineer (PE) in Ghana and a member of Ghana Institution of Engineering. Joshua is a DAAD scholar and has over 19 years’ experience in roadworks and structures. His areas of research interest and professional practice include geotechnical engineering, highway engineering, pavement materials, soil and ground engineering, environment and waste management.

Charles Adams, Kwame Nkrumah University of Science and Technology

D r. Charles Adams is a Transport Leader, astute academic, consultant, mentor, conference speaker, the foundation Centre Director and visionary of the African Centre of Excellence (ACE), Regional Transport Research and Education Centre Kumasi (TRECK) at the College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. Charles is an Associate Professor of Transport Planning and Traffic Engineering at the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. He is a registered professional engineer (PE) in Ghana and a prolific PhD supervisor. Charles has mentored many young doctoral candidates, researchers, engineers, and professionals in Civil and Transportation in Ghana, Africa, and globally. Dr Adams is a member of several international engineering institutions and networks including the International Road Federation - Global (IRF), USA, World Road Association (PIARC), Vice President (Academic), IRF Road Safety Committee, member Technical Committee of the Southern African Transport Conference (SATC), Member, Technical Committee of the Ghana Infrastructure Conferences, Founder of the Transport Logistics and Smart Cities Network, Executive Committee member - Ghana Institution of Engineering and a scholar of the Volvo Research and Educational Foundations (VREF) Researchers Network. His areas of research interest and professional practice include transportation planning and traffic engineering, Infrastructure systems, road asset management systems, modeling, and simulation of transport systems in smart cities, sustainable road safety, formalization of informal Public Transport (Paratransit), technical audits of infrastructure projects, highway engineering, and pavement materials, Net Zero Carbon Transport and electric bus systems, environmental and social risk management of infrastructure projects. He is skilled at stakeholder engagement, and maintains international collaboration with partners in the USA, Europe, and Asia.

Published
2024-12-18
How to Cite
Vordoagu, J. J., & Adams, C. (2024). Effects Of Locust Bean (Parkia Biglobosa) Pod Extract on The Consistency Limits of Marginal Soils for Road Pavement Layer Construction. Journal of Science and Technology, 1(2), 22- 35. https://doi.org/10.4314/just.v1i2.1926