You will see that the surface roughness value of the Sai River to take up effective surface roughness of sand silica 77.5 percent, thus concluding that the Yom River sand can be used to substitute for silica sand.
It can be seen that the flatness of the shortest river sand with a smooth surface silica sand. 77.5 percent to the conclusion that the river sand can be used to replace silica sand.
It can be seen that the surface roughness of the sand river is close to the surface roughness silica sand, Ki was 77.5 concluded that the sand river can substitute silica sand.