What characteristic must the earth fill used in artificial barricades possess?

The characteristic that the earth fill used in artificial barricades must possess is that it should be free from frozen material. This is crucial because when materials are frozen, they can create structural weaknesses or inconsistencies in the barricade. Frozen earth or soil can expand, crack, and cause instability when the temperature rises or when the barricade is subjected to pressure. By ensuring that the fill is free from frozen materials, the integrity and effectiveness of the barricade are maintained, allowing it to provide the necessary protection or functionality intended in its design.