Test Procedure for the Quality of Base and Subbase Materials: Fid-Bau Portal

Test Procedure for the Quality of Base and Subbase Materials

E. J. Oberc / D. D. Chi / C. A. Byus / P. S. Dorsey / R. A. Kochen

This study was undertaken to establish qualitative standards for base and subbase materials in the State of Maryland and to improve stabilizing techniques for inferior materials. An examination of a number of strength parameters and tests was conducted on specification crushed stone. As a result of this investigation, it was decided that further testing for the quality of base materials would be conducted using the triaxial test. Tentative standards for qualitative classification of base and subbase materials were established based on the triaxial. Phase II testing investigated the effects of several types and percentages of additives on the quality of specification and non-specification base materials. The additives studied included portland cement, lime and asphalt emulsion. Crushed stone, gravel and sand aggregate were the base materials tested. During Phase II, it was discovered that non-specification material was not readily available in Maryland. This was contrary to one of the basic premises on which the study was initiated. Based on the lack of non-specification material and several other considerations, a decision was made to terminate the study. This eliminated a section of Phase II testing and all of Phase III, field performance and evaluation. The results of the testing indicates that the triaxial test may be a good tool for evaluating the quality of crushed stone when untreated or when treated with lime or cement. However, some of the results for other materials and additives are inconsistent with our current practice and experience. It is believed that thse discrepancies, between the field and laboratory situations, are due to differences in loading and other test conditions.