Texas Triaxial - R Value Correlation

The Testing and Research Section of the Louisiana Department of Highways, in cooperation with the Bureau of Public Roads, has been engaged in an effort to correlate Resistance Value (R-Value) with the Texas Triaxial Strength Class system which is the basis of the flexible pavement design method currently used in Louisiana. Parallel to this, an attempt was made to correlate R-Value with the Group Index Method. The materials selected for this project cover common Louisiana soils, plus artificially produced materials designed to fall within the range of Texas Triaxial Class 2. The test results were analyzed using statistical concepts which showed an apparently good correlation to exist between R-Value and Texas Triaxial Strength Classes. The correlation for R-Value and Group Index appeared to be fairly poor, as can be seen by the scatter arrangement of the variables.