RUTTING EVALUATION OF SUBGRADE SOILS IN OHIO

Abstract

The results of several previous investigations have led to the conclusion that rutting criteria should be included in any pavement design methodology that attempts to achieve the goal of improved pavement serviceability. Moreover, in some practical cases, it is necessary to estimate the rutting expected to occur in a pavement system during a certain period. Therefore, it is necessary to develop a scheme for the estimation of rutting. Because it is the foundation of the pavement, the subgrade makes a considerable contribution to its rutting. The objective of this research was to study the rutting in subgrade soils experimentally. The rate-process theory approach was used for the analysis of the results. Five types of silty soils were obtained from four different construction sites in Ohio, and laboratory-prepared samples were used for uniaxial dynamic testing. A direct general relationship that relates rutting to the dynamic modulus and the applied stress level was developed. On the basis of that relationship, a scheme for the estimation of subgrade permanent deformation is proposed and design nomographs for the soils studied were developed. The findings of this study are limited to the types of soils (silty and clayey) tested; further studies should indicate their applicability to other materials also. /Author/