Comparison of moisture density relationship tests in civil engineering materials

Abstract

Introduction: Current Moisture Density Relationship (MDR) tests use a manual method of compaction that is physically arduous and subject to some technical problems. This project aims to use a vibratory method of compaction using an electric jackhammer to address these problems. Background: The MDR test is used to establish the Maximum Dry Density (MDD) and the Optimum Moisture Content (OMC) of coherent constriction materials for embankments, footings and pavements. This result is compared to the result of a field density test to find the relative density for quality control of construction projects. Methodology: A 1240 W electric jackhammer with a flat compaction plate was to supply compaction energy to the sample. The jackhammer was initially used hand held to find the compaction characteristics of the jackhammer then an apparatus was designed and built to hold the jackhammer during operation. Comparison was made between the results from Queensland Main Roads test method Q110A and the project results. Testing consisted of 4 test series exploring the relationships between: - The time of compaction and maximum dry density. - The reciprocating mass of the electric jackhammer and maximum dry density. - Standard deviation, spread of results, average maximum dry density and optimum moisture content between the project method and test method Q110A. - The performance of the project method as applied to different soil types. Conclusions: The project results suggest that a vibratory method of compaction may be a solution to some of the technical and ergonomic problems associated with manual compaction methods. More tests are needed to validate the method.