Research Article
Lime Stabilization Effects on Geomechanical Properties of Kombe Mbanga Soils Road Subgrade (Cameroon)
Guimezap Kenou Willy Chance*
,
Nie Noumsi Thierry Constant,
Taypondou Darman Japhet,
Asmaou Daoua Youssoufa Yasmine
Issue:
Volume 12, Issue 3, September 2026
Pages:
84-97
Received:
13 June 2026
Accepted:
1 July 2026
Published:
24 July 2026
Abstract: Road infrastructure in Cameroon experiences rapid deterioration due to intense seasonal rainfall, high temperatures, and the predominance of weak lateritic soils in tropical environments. These unfavorable conditions reduce pavement performance, increase maintenance costs, and hinder sustainable transportation development, particularly on rural road networks. Soil stabilization using locally available materials has emerged as a cost-effective strategy for improving the engineering properties of these problematic soils. This study evaluates the effectiveness of locally sourced quicklime in enhancing the geotechnical characteristics of lateritic soils collected from the Kombe-Mbanga area in Cameroon and assesses its suitability for road subgrade applications. Ten representative soil samples were collected and characterized through laboratory testing, including particle size distribution, Atterberg limits, Modified Proctor compaction, California Bearing Ratio (CBR), and direct shear strength tests. The tests were performed before and after quicklime stabilization to quantify changes in the soils' mechanical behavior. In addition, statistical analyses were conducted to investigate the relationships between key geotechnical parameters and bearing capacity. The results demonstrate substantial improvements following stabilization. The average CBR increased from 9.04 to 45.08, indicating a significant enhancement in load-bearing capacity. Cohesion increased from 27 to 57 kPa, while the internal friction angle improved from 30° to 57°, reflecting greater shear strength and stability. Statistical analysis further revealed a strong negative correlation between the plasticity index and CBR (r = −0.67), confirming that high plasticity and fine particle content are the primary factors responsible for the poor engineering performance of the untreated soils. These findings demonstrate that locally available quicklime provides a simple, economical, and effective stabilization technique capable of transforming weak tropical lateritic soils into suitable road subgrade materials. The study offers practical guidance for the rehabilitation and construction of durable rural roads in Cameroon and other tropical regions with similar geotechnical and climatic conditions.
Abstract: Road infrastructure in Cameroon experiences rapid deterioration due to intense seasonal rainfall, high temperatures, and the predominance of weak lateritic soils in tropical environments. These unfavorable conditions reduce pavement performance, increase maintenance costs, and hinder sustainable transportation development, particularly on rural roa...
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Research Article
Mathematical Modeling for Road Accident Analysis in Bangladesh: Nonlinear Deterministic, Exposure-Adjusted Count, and Seasonal Time-Series Approaches
Sree Pradip Kumer Sarker*,
Md. Shahid Mamun
Issue:
Volume 12, Issue 3, September 2026
Pages:
98-118
Received:
26 July 2026
Accepted:
8 August 2026
Published:
24 August 2026
DOI:
10.11648/j.ijtet.20261203.12
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Abstract: This study establishes a coherent mathematical model for the investigation of road accidents in Bangladesh by integrating nonlinear deterministic modeling, count regression with exposure, normalized fatality-rate estimation and seasonal time-series forecasting. The analysis constructs a balanced monthly panel from January 2023 to December 2025, with 36 national monthly observations and 288 division-month observations, using four synchronized datasets on population, monthly accidents, fatalities by type of vehicle, and vehicle involvement. During the study period, Bangladesh recorded 17,046 accidents, 15,994 deaths, 20,389 injuries and 36,383 total casualties indicating a persistently high and fluctuating national toll. Analysis of the deterministic model shows that harmonic quadratic equations best describe the accidents and fatalities, a harmonic linear equation the injuries, and a cubic equation the accident severity index, confirming the absence of any single common trend structure across the burden dimensions. Seasonal-index analysis revealed that June is the month with the highest number of accidents, fatalities and injuries, while August is the lowest month for accidents and fatalities and November for injuries, indicating consistent annual patterns. At the division-month level, the negative binomial model is significantly better than the Poisson model, reducing the AIC by 275.558 points, indicating significant overdispersion in accident occurrences. The harmonic OLS model for the fatality rate accounts for 46.1% of the variation in fatalities per 100,000 individuals. The SARIMAX forecast has a 12-month seasonal memory and projects a rise in June 2026 and a fall in August 2026. The results suggest that the incidence of road accidents in Bangladesh is influenced by nonlinear trends, seasonal variations, exposure disparities, and random temporal correlations, providing a mathematically coherent basis for risk assessment and road safety strategies.
Abstract: This study establishes a coherent mathematical model for the investigation of road accidents in Bangladesh by integrating nonlinear deterministic modeling, count regression with exposure, normalized fatality-rate estimation and seasonal time-series forecasting. The analysis constructs a balanced monthly panel from January 2023 to December 2025, wit...
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