Liquid limit determination of clayey material by Casagrande method, fall cone test and EBS parameter

Abstract

Casagrande and fall cone tests are standard methods widely used for liquid limit determination. This is a parameter that, in addition to the information provided by plastic limit assessment, allows the evaluation of the plasticity of soils. This study carried out the determination of liquid limit of 18 clayey samples by Casagrande and fall cone methods in order to compare them. A high correlation was found between the results of both methods. Moreover, the most recent equation proposed on literature for the comparison between methods was applied, and it seems suitable for the prediction of liquid limit assessed by fall cone test and the experimental value achieved by Casagrande device. As expected, good correlations between liquid limit, phyllosilicate amount and type of clay minerals was noticed. As complement, equivalent basal spacing (EBS) parameter was calculated and tested. Good correlations between this parameter and liquid limit measured were observed only for samples with <70% of phyllosilicate content; when the analysis is applied to the samples with higher amount of phyllosilicates, there is not a good match, suggesting that EBS calculation is not reliable in those cases.