Quick Methods of Measurement of Relative Compaction and Moisture Content
The need of compaction control is well-recognized to ensure safety and satisfactory performance of fill body. Minimum relative compaction is commonly used in the end-product specification for earthworks. The Hilf method is a way to determine the relative compaction and deviation from optimum moisture content without the need to know the moisture content of soil. Infrared with convection heating is a drying method to dry soil rapidly (within 3.5 hours for common fill materials in Hong Kong). These two methods facilitate the quick determination of the relative compaction. This paper examines these two quick methods. It also presents the review of the applicability of the Hilf method in fill compaction control based on 271 pairs of results conducted in public works projects and the effectiveness of the infrared with convection drying in measuring moisture content of soil based on 167 sets of test results. The results showed that there is a reasonably good correlation between the relative compaction determined from the Hilf method and sand replacement test, with an absolute difference in relative compaction mainly within 3%; while the moisture content obtained from the infrared with convection drying and the conventional oven drying method are statistically identical with majority of the results having differences less than 0.4% which is considered practically insignificant for geotechnical engineering applications.
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