TITLE:
California Bearing Ratio for Cohesive Soils from Quasi Static Cone Tests
AUTHORS:
Robert Kaweesi, Michael Kyakula
KEYWORDS:
California Bearing Ratio, Quasi Static Consistency Limits, Plastic Limit, Liquid Limit, Plasticity Index
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.13 No.2,
June
26,
2023
ABSTRACT: The
California bearing ratio (CBR) test is the most widely spread method of
determining the bearing strength of the pavement material and is fundamental to
pavement design practice in most countries. This test is expensive, laborious
and time consuming, and to overcome this, Quasi static cone penetrometer
machine was fabricated and used to measure the consistency limits (liquid
limit-LL, Plastic limit-PL and Plasticity index-PI), which were used to develop
an empirical equation to determine CBR. Soil samples were collected and
unsoaked CBR, PL, LL and PI were determined according to BS 1377 part 9 and BS
1377-2; 1990.
Quasi static penetration forces at 20 mm depth of penetration were also determined at
consistency limits. It was found that the force of 1020 gf and 60 gf was achieved at a depth of 20 mm at PI and LL
respectively. The correlation and regression analysis between consistency limits,
and the experimental CBR obtained showed coefficient of determination, R2 = 0.907 between CBR and all the parameters using multiple linear regression
analysis (MLRA). The regression equation developed was used together with the
relationship developed between the Quasi static Penetration force at
consistency limits and the tested consistency limits to come up with the
General Empirical Equation. Verification of the formula showed that the
correlation can be used accurately to determine the un soaked CBR.