Triaxial Characterization of Minnesota Road Research Project Granular Materials

Abstract

Six granular materials were used as base and subbase materials in the flexible pavement test sections for the Minnesota Road Research (Mn/ROAD) project. Crushed/fractured particles are not allowed in aggregate classes CL-1Fsp, CL-1Csp, CL-3sp, and CL-4sp. Ten to 15 percent crushed/fractured particles are required for CL-5sp. One hundred percent crushed/ fractured particles are required for CL-6sp. A comprehensive laboratory testing program was established to determine pertinent engineering properties of the granular materials. Rapid shear tests and repeated-load tests were conducted to determine the shear strength parameters (friction angle and cohesion), resilient modulus, rutting potential, stress history effects on shear strength, and moisture susceptibility. The results from the rapid shear tests and permanent deformation tests show that the rutting potential of a granular material can be characterized from rapid shear test at a confining pressure of 15 psi (103.35 kPa). The rutting parameter A was a function of the shear strength of the granular materials. The shear strength results obtained from rapid shear tests performed at a confining pressure of 15 psi reflect the rutting trends observed in the low-volume road test sections at the Mn/ROAD project. Results from repeated-load tests were used to develop the parameters for K-θ, UT-Austin, and Uzan’s models for evaluating the resilient modulus of granular materials. The axial strain values calculated from the resilient modulus models appear to be in good agreement with the measured axial strain values, except for the very low shear strength material CL-1Csp.

Get full access to this article

View all access options for this article.

References

Thompson

M. R.

, and Smith

K. L.

. Repeated Triaxial Characterization of Granular Bases. In Transportation Research Record 1278, TRB, National Research Council, Washington, D.C., 1990, pp. 7–17.

May

R. W.

, and Witczak

M. W.

. Effective Granular Modulus to Model Pavement Responses. In Transportation Research Record 810, TRB, National Research Council, Washington, D.C., 1981, pp. 1–90.

Uzan

Characterization of Granular Material. In Transportation Research Record 1022, TRB, National Research Council, Washington, D.C., 1985, pp. 52–59.

Pezo

R. F.

A General Method of Reporting Resilient Modulus Tests of Soils—A Pavement Engineer’s Point of View. Presented at the 72nd Annual Meeting of the Transportation Research Board, Washington, D.C., 1993.

Rada

, and Witczak

M. W.

. Comprehensive Evaluation of Laboratory Resilient Moduli Results for Granular Material. In Transportation Research Record 810, TRB, National Research Council, Washington, D.C., 1981, 23–33.

Calibrated Mechanistic Structural Analysis Procedures for Pavements, Vol. 2. Appendices. National Cooperative Highway Research Program Project 1-26. TRB, National Research Council, Washington, D.C., March 1990.

Garg

, and Budiman

. Effect of Large Size Aggregates on the Performance of Base Materials for Flexible Pavements. Presented at the 73rd Annual Meeting of the Transportation Research Board, Washington, D.C., 1994.

Thompson

M. R.

, and Nauman

. Rutting Rate Analyses of the AASHO Road Test Flexible Pavements. In Transportation Research Record 1384, TRB, National Research Council, 1993, pp. 36–48.

Khedr

S. A.

Deformation Mechanism in Asphaltic Concrete. Journal of Transportation Engineering, ASCE, Vol. 112, No. 1, Jan. 1986.

10.

Stroup-Gardiner

, and Newcomb

D. E.

. Investigation of Hot Mix Asphalt Mixtures at Mn/ROAD—Final Report. Minnesota Department of Transportation, July 1996.