In-situ penetration tests have been widely used in geotechnical and foundation engineering for site investigation in support of analysis and design. The standard penetration test (SPT) and the cone penetration test (CPT) are two typical in-situ penetration tests. The dynamic cone penetration test shows features of both the CPT and the SPT. The DCPT is performed by dropping a hammer from a certain fall height and measuring penetration depth per blow for each tested depth. The DCPT is a quick test to set up, run, and evaluate on site. Due to its economy and simplicity, better understanding of DCPT results can reduce efforts and cost for evaluation of pavement and subgrade soils. Present practice in determining the adequacy of a compacted subgrade is to determine the dry density and water content by either the sand-cone method or the nuclear gauge. The use of the resilient modulus (Mr) has recently become mandatory for pavement design. To find the Mr, a time-consuming test is required which demands significant effort. Therefore, a faster and easier alternative for compaction control in road construction practice is desired. To this end, the present project is a step towards the generation of sufficient data to create appropriate correlations between subgrade parameters and DCPT results. The present research considers several subgrade soils at different road construction sites. Each soil is tested in the field and in the laboratory. The field testing includes the DCPT and nuclear density gauge tests. Based on analysis of this testing, the relationships between the DCPT results and the subgrade parameters such as unconfined compression strength and resilient modulus are obtained.
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