Final answer:
Subsidence is the term that refers to the settling or moving of concrete due to its mass. Modern lightweight concrete is used in construction for its load reduction, longevity, and thermal protection.
Step-by-step explanation:
The term that refers to the settling or moving of concrete over many years due to its heavy mass is known as subsidence. This phenomenon can be affected by various factors such as soil compaction, extraction of resources, or water withdrawal. Concrete, particularly the more modern lightweight concrete, is used extensively in construction due to its beneficial properties like the reduction of load, which allows for faster building rates, and its durability, which makes it longer-lasting. Additionally, it serves as an excellent thermal protector, offering advantages over traditional materials like brick. Despite its strength and flexibility, even concrete can be subject to subsidence under certain conditions over extended periods.