The method of calculating the soil maximum dry density and the optimum water content based on the high-order interpolation function of Newton

The subgrade compaction is a significant gauge of subgrade’s quality assessment. Meanwhile, the accuracy of compactness mainly lies in the maximum dry density by indoor standard compaction test. In fact, there are some artificial uncertainties in the process of measuring the maximum dry density, including underutilized experimental data, not accurate numerical analysis, calculation difficulty, data distortion, etc. To avoid the above drawbacks, the method of calculating the soil maximum dry density and the optimum water content, which are based on the high-order interpolation function of Newton is put forward. This method enables to better reflect the functional relation between the optimum moisture content and maximum dry density. By means of errors, the experimental data can be fully utilized and only small errors exist, which is completely in accordance with the specification requirements.