iquid limit determination of medium to high plasticity Algerian soils using fall-cone vs Casagrande percussion cup methods

Abstract

Determining the liquid limit (LL) of fine-grained soils is crucial in geotechnical site investigations. For a long time, the Casagrande Percussion Cup (CPC) test has been the standard method for this purpose. Although the Fall Cone Test (FCT) provides more repeatable results compared to the CPC test, its utilization remains limited in Algeria. To assess the effectiveness of the FCT, a comparative study was conducted using mixtures of bentonite and natural soils from Algeria. The choice of bentonite as an additive to soils with low plasticity is in order to formulate new samples with a wide range of plasticity. Our results showed that the LL CONE values slightly exceeded the LL CUP values for natural soil samples with medium plasticity. However, for soils with high and extreme plasticity, the LL CONE values significantly underestimated the LL CUP values. To address this issue, an equation was developed to convert LL CONE measurements to LL CUP values. This equation is consistent with previous literature and could help promote the adoption of the FCT method for geotechnical site investigations in Algeria.