Misaki SHOUJI
Research on Durability Evaluation of Grain as Sub-base Material
Teruhiko MARUYAMA
This research aims to make aggregate minute grain, to evaluate durability of the aggregates minute grain as sub-base material, and thus, to compare durability of the aggregates minute grain to that of natural macadam sub-base. Three kinds of compactor were used to prepare specimens, namely Marshall compactor, gyratory compactor and steel roller compactor. Water retention of the materials was evaluated. For evaluating the durability, the sub-base materials were classified into soaked conditions, and thus, universal testing machine was used to evaluate California Bearing Ratio (CBR) of the sub-base materials in both conditions. GAMES, which is a commercial software based on theory of multi-layer elastic, was used to evaluate capacity of the sub-base materials supporting equivalent 5 ton wheel loads.
This study found the following results. Water retention of the sub-base materials is not dependent on loading method. Water retention of the aggregate minute grain is larger than that of natural macadam sub-base. As a result, durability of the aggregate minute grain is inferior to that of natural macadam sub-base material. When numbers of equivalent 5 tons wheel load was applied 1,300 times, volume of conventional sub-base material shrank approximately 1%. Under the same loading application, volume of wet sub-base material shrank about 5%. It can be concluded then, the wet sub-base material is more suitable used for sidewalk or road serving light traffic.
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