The dynamic cone penetrometer as a validation tool for compaction of crushed rock base

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The traditional method of verifying the level of compaction achieved on construction sites using sand replacement method is very time consuming and sometimes difficult to perform. Furthermore, on sites open to traffic the safety of the inspectors while conducting sand cone testing on a construction site can be a concern. Therefore, the objective of this study is to ascertain the extent to which the DCP can be used as a tool to verify the level of compaction achieved in-situ on a crushed rock base. Studies were conducted on an on-going road project to ascertain the extent to which the Dynamic Cone Penetrometer (DCP) can be applied in compaction verification on crushed rock. Compaction studies were conducted on three sections of the project site using a 17 ton vibratory roller. DCP test was conducted alongside sand replacement test to determine the level of compaction for one, two, four and eight roller passes. A linear relation was developed between the level of compaction and DPI values from the DCP test which is of form Log (LC) = a - p* log (DPI), where LC is level of compaction by the sand replacement method and DPI is the penetration rate of the DCP. The values of a and p were found to 2.134 and 0.109 respectively. A further study was also conducted in the laboratory to adjust the DPI values at various water content to constant water content. Three levels of compaction were calibrated and the result relation is linear and is of the form DPI= K + tav, K is a constant that depends on the level of compaction and w is the water content of the material at time of testing. LC=93% CR-B10: DPI = 3.874 + 0.855w LC-97% CR-B25: DPI = 1.228 + 0.836w LC=101% CR-B55: DPI = 1.316 + 0.470w
A Thesis Submitted to the Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi In Partial Fulfillment of the Requirement for the Award of the Degree of Master of Science.