Correlation Between CBR Value and Plasticity Index of Base Course Material in Flexible Pavement
Date
2024-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
I.O.E
Abstract
The California Bearing Ratio (CBR) serves as a crucial indicator of base course strength, informing the thickness design of the pavement. It signifies the material's capacity to withstand loads and resist deformation, with higher values suggesting stronger base course materials capable of bearing heavier loads with minimal deformation. Plasticity Index (PI) is another pivotal parameter guiding engineers in assessing the suitability of the base course for pavement design. A larger PI implies a higher clay content, potentially compromising the base course's strength and stability. This prompts researchers to explore the potential relationship between CBR and PI for base course. Twenty-one samples of base course were gathered from Lalitpur, Makwanpur, and Dhading, ensuring compliance with the Standard Specifications for Road and Bridge Works, 2016 (SSRBW). In assessing CBR, Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) are also considered. Thus, OMC, MDD, and PI are treated as independent variables to formulate an expression for estimating CBR. Utilizing Multiple Linear Regression in Excel, a predictive model for CBR was established, demonstrating a strong correlation between predicted and observed CBR, with an R2-value of 0.81. This model streamlines testing procedures by facilitating the determination of CBR values for base courses without extensive testing. Laboratory tests indicate that even with a PI exceeding 6 (e.g., PI = 8), the CBR value remains above 80%.
Description
The California Bearing Ratio (CBR) serves as a crucial indicator of base course strength, informing the thickness design of the pavement. It signifies the material's capacity to withstand loads and resist deformation, with higher values suggesting stronger base course materials capable of bearing heavier loads with minimal deformation.
Keywords
CBR, SSRBW, Correlation