Dynamic Cone Penetration Test: An Alternative Method for Quality Control of Subgrade Layer

Abstract

The durability of subgrade layer depends on the and compactness of the materials. However, the commonly used method for checking the density of subgrade layer is costly and time consuming. This study helps to eradicate these problems by introducing an alternative method to check the density at field. In this research the relationship between Dynamic cone penetrometer (DCP) and soil dry density was developed. The collected soil samples from LGED road development projects at 6 different locations were selected to develop the relationship. Grain size analysis, Liquid limit and Plastic limit, Specific gravity, Standard proctor test, sand cone test were performed on these samples. In laboratory the standard ASTM method was followed for compaction, a 4-inch diameter cylindrical mold and 2.5 kg hammer with drop height of 12 inch was used to prepare the test sample. The test samples were prepared at different density by varying the compaction rate and DCP penetration were measured. A number of DCP test were performed on compacted test samples to determine the penetration rate. Then the relationship were developed between DCP penetration and dry density. A linear relationship was developed between DCP penetration and dry density. The relationship developed from this study can be used to checked the density at field using DCP more efficiently comparing with sand cone method.