A laboratory study of horizontal confinement effect on the dynamic cone penetration index of a lateritic soil

The Dynamic Cone Penetrometer (DCP) has been proposed as a potentially effective tool for compaction quality verification but the correlation equations are established in situ, which is tedious and time consuming. This study is part of a larger study seeking to investigate how to extend the calibration equation obtained from in-mould laboratory tests for use in situ. In this study the effect of mould diameter on the dynamic cone penetration index (DPI) during the DCP test determined at the optimum water content for the case of lateritic clayey sand is investigated. In-mould DCP tests were performed on a lateritic-clayey sand in seven moulds of different diameters ranging from 100 mm to 600 mm and at levels of compaction of 80%, 90% and 100% of the modified Proctor maximum dry density. The study presents the correlation parameters for any ratio of mould to-cone-diameter varying from 5 to 30. Based on the results, the study proposes a preliminary procedure to derive the in situ correlation equation from that obtained from the in-mould laboratory tests in the CBR mould.