Use of the One-Point Proctor Modified Compaction Method in Family Compaction Curves Possessing a Limited Trend Characteristic

A significant proportion of earthworks involves the processing and compaction of heterogeneous subgrade and fill materials. More specifically, working-lots cannot be represented by one value for their Modified Proctor maximum density even if they belong to the same group of materials with the same AASTHO classification. Thus, heterogeneity leads to the need for adopting a shorter method for determining the Modified Proctor maximum density for any given working-lot. This paper adopts the AASTHO prediction method, which is given in its standard method of testing a family of curves, the one-point method (AASHTO Designation: T 272-04). This method provides for the rapid determination of the maximum density and optimum moisture content of a soil sample, utilizing a family of curves and a one-point determination. The latter is performed by the compaction of a sample of soil obtained from a given working-lot by means of the Modified Proctor energy effort. This AASHTO method postulates that the family of curves discussed constitutes a group of typical soil moisture-density relationships that reveal certain similarities and trend characteristics of the soil type and source. In many cases, however, this family of curves does not reveal the required trend characteristics. Thus, an averaging procedure is required in order to overcome this limitation. An adjustment (averaging) procedure is developed in the present paper. Employing three practical examples, the paper demonstrates the effectiveness of the proposed procedure.