Proctor and Harvard Miniature Compaction Energy Comparison

Abstract

The objective of this research was to investigate the potential for the Harvard Miniature Compaction Apparatus (HMCA) to replace that of Proctor compaction for fine-grained soils by equating the applied energy of the two compaction methods. The HMCA tamper rod includes a spring, so the energy applied by the HMCA was developed by calculating the potential energy of the spring. The displacement of the spring was adjusted to provide reduced energy (300 kN-m/m3 [6,200ft-lbf/ft3]), standard energy (600 kN-m/m3 [12,400ft-lbf/ft3]), or modified energy (2,700 kN-m/m3 [56,250ft-lbf/ft3]). Soil moisture content and dry unit weight curves were developed for compacted specimens using two fine-grained soils prepared using both methods. The best comparisons between the methods occurred at low energy levels. At standard energy for a red clay, there was a 0.40 % and 0.35% difference in optimum moisture content and maximum dry unit weight, respectively. Similarly, at reduced energy for kaolinite, there was a 0.52 % and 0.73% difference for the optimum moisture content and maximum dry unit weight, respectively. Based on the results of this research, there is potential for the HMCA, with potential energy adjustments, to be used in place of traditional compaction for fine-grained soil specimens, which can reduce the resources needed to conduct the compaction tests.