Effect of fine material content on the CBR of Iran saturated soils

چکیده مقاله

The California bearing ratio (CBR) is an important index of soil quality for use in road construction and base stabilization. The CBR test can be performed in site and laboratory. CBR of a soil mass depends on several factors, the most important of which are the soil grading, fine material content, soundness of aggregates, moisture content, and soil compaction. Considering the wide range of factors affecting CBR, this study investigates the effect of fine material content on the CBR of mixed material soils. This investigation was performed by conducting laboratory CBR tests on over 400 soil samples with maximum density under saturated conditions. The samples were collected from a wide range of locations in Iran. The test results were used to formulate some equations for the relationship between CBR and the fine material content of soils. These equations showed that as the fine material content of the soils increases, their CBR decreases. It was found that for two soils with the same fine material content, one can obtain a range of CBRs with up to 90% difference between their maximum and minimum values. The results also showed that aggregate material can affect CBR by up to 67%.