Correlations between laboratory dynamic CBR and compaction parameters of unbound coarse aggregate for base courses

Publisher's full text

It is well known that the determination of fundamental engineering properties of materials is the key to their inclusion within quality control assessments and pavement design. Although using of maximum dry density and optimum moisture content has been widely accepted in quality control assessments, it may not provide the mechanistic properties of the compacted material, namely, strength or stiffness. On the other hand, the static plate loading test used for quality control of roads is relatively expensive as compared with lighter equipment used nowadays to control the bearing capacity of compacted unbound materials. In this context, it has become necessary to find a simple and quick test that can be used in assessing the bearing capacity of Swedish base course material. For this purpose, several unbound granular California bearing ratio (CBR) samples were prepared and compacted using modified Proctor compaction for a wide range of molding water contents. Then, the CBR samples have been tested by a dynamic California bearing ratio device. This research provides a data base for future adopting of the dynamic CBR test as a light equipment used for quality assurance during roads construction. Regression equations have been developed to predict the laboratory dynamic CBR (CBRLD) from the molding water contents and the dry densities with relatively high correlation coefficients. These equations can be used in predicting the CBRLD values for unbound granular materials compacted and tested at similar conditions as in that developed for.

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