Rammer construction has a lot of terrain can not use rammer operation, for example: gravel: if it is simple gravel gravel rammer construction is no problem, can be ignored. But if it is a lot of gravel and gravel block is very large, then the first either transport away from the stone, or in situ treatment into a small broken road stone, small gravel can be in the process of ramming construction fully settled. 

There is also sandy soil soil can not be constructed rammer construction: sandy soil has very unstable characteristics, if the water content is too much or not at all, basically can not carry out the Shi Nei Gong, you have seen the hammer in the desert? Sand mobility is particularly large, wind and rain infiltration of the terrain will be able to easily change. So pure sandy soil in the strong tamping operations before, is the need for mixing to change the characteristics of the soil to reach the full standard before the strong tamping operations.