ASTM D1883-16 PDF Download

The ASTM D1883-16 standard is used to determine the potential strength of subgrade, subbase, and base course materials for road and airfield pavements. The California Bearing Ratio (CBR) value obtained from this test is an essential component in several flexible pavement design methods.

The standard provides guidelines for testing materials with a maximum particle size of less than 3/4 inch (19 mm). However, if the materials to be tested have larger particles, the test method allows for modifying the gradation of the material so that it can pass a 3/4 inch sieve while maintaining the same total gravel fraction. It is important to note that while this modification helps avoid errors in testing, the modified material may have different strength properties than the original.

The standard also recognizes that materials with a substantial percentage of particles retained on the No. 4 sieve (4.75 mm) may result in more variable CBR results compared to finer materials, requiring additional trials to establish reliable CBR values.

The test method allows for determining the CBR of a material at its optimum water content or within a range of water contents specified by the client. The dry unit weight is typically expressed as a percentage of the maximum dry unit weight determined by other test methods.

It is important to acknowledge that the competence of personnel, as well as the suitability of equipment and facilities, play a crucial role in achieving reliable results. While compliance with ASTM Practice D3740 indicates competence, it does not guarantee reliable results as various factors can influence the outcome.