AASHTO T 193-13（2021） Standard Method of Test for The California Bearing Ratio.pdf

Standard Method of Test for The California Bearing Ratio AASHTO Designation:T 193-13(2021) Technically Revised:2013 Reviewed but Not Updated:2021 Editorially Revised:2021 Technical Submittee:1a Soil and Unbound Recycled Materials AASHIO American Association of State Highway and Transportation Officials 555 12th Street NW Suite 1000 Washington DC 20004 Standard Method of Test for The California Bearing Ratio AASHTO Designation:T 193-13(2021) AASHIO Technically Revised:2013 Reviewed but Not Updated:2021 Editorially Revised:2021 Technical Submittee:1a Soil and Unbound Recycled Materials 1. SCOPE 1.1. This test method covers the determination of the California Bearing Ratio (CBR)of pavement subgrade subbase and base/course materials from laboratory pacted specimens.The test method is primarily intended for but not limited to evaluating the strength of cohesive materials having maximum particle sizes less than 19 mm (/4 in.). 1.2. When materials having maximum particle sizes greater than 19 mm (/4 in.)are to be tested this test method provides for modifying the gradation of the material so that the material used for tests all passes the 19.0-mm (3/4-in.)sieve while the total gravel 4.75-mm (No.4)to 75-mm(3-in.) fraction remains the same.While traditionally this method of specimen preparation has been used to avoid the error inherent in testing materials containing large particles in the CBR test apparatus the modified material may have significantly different strength properties than the original material.However a large experience base has developed using this test method for materials for which the gradation has been modified and satisfactory design methods are in use based on the results of tests using this procedure. 1.3. Past practice has shown that CBR results for those materials having substantial percentages of particles retained on the 4.75-mm (No.4)sieve are more variable than for finer materials. Consequently more trials may be required for these mat...