River sands and river gravels are the main sources of concrete aggregates in this country. Concrete quality and concrete stress depend on the quality of aggregates. So quality of aggregates determine the design and durability of concrete structure. Here, river sands and gravels were collected from representative point of many rivers and streams, and their basic natures were tested. Also concrete stress test for each aggregate was conducted to give allowable stress and other important data which are necessary for the design and construction of concrete structures.