GEOTECHNICAL EVALUATION OF BAMBOO ASH ON THE CALIFORNIA BEARING RATIO CHARACTERISTICS OF CLAY SOIL
Faculty
Department
Year of Publication
Publication Type
Abstract
Clay soils at many construction sites often exhibit low strength and high plasticity, making them unsuitable for supporting heavy structural loads without proper stabilization. This study aimed to investigate the potential of bamboo ash (BA) as an environmentally friendly and cost-effective soil stabilizer to improve the engineering performance of clay soils. The research specifically
examined how varying BA contents (5%, 10%, 15%, and 20% by dry weight) affect the geotechnical properties and California Bearing Ratio (CBR) characteristics of clay soils, with the goal of addressing the problem of weak subgrade performance in road and foundation construction.
The materials used were locally sourced clay soil and bamboo ash produced from the controlled burning of bamboo plants. Laboratory testing was carried out on both untreated and BA-treated soils. The experimental program included soil classification tests—specific gravity, particle size distribution, and Atterberg Limits—compaction tests to determine Maximum Dry Density (MDD) and Optimum Moisture Content (OMC), and CBR tests to evaluate load-bearing capacity. The natural clay was classified as A-4 and A-5 according to the AASHTO system, while BA was used as the stabilizing additive in different proportions. Results indicated that untreated clay soils exhibited low CBR values. The addition of BA improved both MDD and CBR, with the highest performance observed at 15% BA content.
Beyond this level (20%), both MDD and CBR values declined, and Atterberg Limit results showed an overall increase in plasticity with higher BA content. The findings demonstrate that BA has significant potential as a sustainable soil stabilizer, particularly at the 15% level, for improving clay soil strength and bearing capacity. However, the reduction in performance at higher contents and the rise in plasticity highlight the need for further microstructural analysis and field trials to develop practical guidelines for its use in construction projects.
examined how varying BA contents (5%, 10%, 15%, and 20% by dry weight) affect the geotechnical properties and California Bearing Ratio (CBR) characteristics of clay soils, with the goal of addressing the problem of weak subgrade performance in road and foundation construction.
The materials used were locally sourced clay soil and bamboo ash produced from the controlled burning of bamboo plants. Laboratory testing was carried out on both untreated and BA-treated soils. The experimental program included soil classification tests—specific gravity, particle size distribution, and Atterberg Limits—compaction tests to determine Maximum Dry Density (MDD) and Optimum Moisture Content (OMC), and CBR tests to evaluate load-bearing capacity. The natural clay was classified as A-4 and A-5 according to the AASHTO system, while BA was used as the stabilizing additive in different proportions. Results indicated that untreated clay soils exhibited low CBR values. The addition of BA improved both MDD and CBR, with the highest performance observed at 15% BA content.
Beyond this level (20%), both MDD and CBR values declined, and Atterberg Limit results showed an overall increase in plasticity with higher BA content. The findings demonstrate that BA has significant potential as a sustainable soil stabilizer, particularly at the 15% level, for improving clay soil strength and bearing capacity. However, the reduction in performance at higher contents and the rise in plasticity highlight the need for further microstructural analysis and field trials to develop practical guidelines for its use in construction projects.
Supervisor(s)
co-supervisor