Final answer:
The characteristic that is not associated with Roman imperial monuments built using concrete is B.walls are always thin membranes.
Step-by-step explanation:
The characteristic that is not associated with Roman imperial monuments built using concrete is B) Walls are always thin membranes.
Roman architecture revolutionized the use of concrete by combining it with the structural shape of the arch. Arches can bear immense weight and redistribute it from the top to its sides and down into the ground. The Romans manipulated and relied on the shape of the arch to create impressive structures.
Examples of Roman architectural innovations using concrete include the Pantheon, Vespasian's Colosseum, and the Markets of Trajan. These structures showcased the Romans' ability to build on a grand scale and their appreciation for architectural history.