Final answer:
The term 'cobweb' in relation to cement describes the stringy, unmanageable consistency it gets when it begins to set beyond its workable timeframe. This typically happens once the pot life or working time has expired and the cement starts the setting process. The specific type of cement was not mentioned, but the concept applies broadly to most cementitious materials after their workable duration has lapsed.
Step-by-step explanation:
The cement that will "cobweb" if the working time has expired is cement that has started to set and is undergoing the initial set phase, which is largely controlled by the chemistry of the cement and environmental conditions such as temperature and humidity. The term cobwebbing generally refers to the stringy, difficult-to-manage consistency that plaster or joint compound takes on when it begins to set or cure beyond its workable timeframe. In the context of cement or more specialized products like dental or plastering cement, this refers to the loss of plasticity which makes it unusable for the intended purpose, like casting or smooth application.
The working time, also known as pot life, is the duration during which a mixed batch of cement remains workable and is crucial for professionals to be able to apply it effectively. Once this time has lapsed, the cement begins the setting process, where the mix becomes stiff and loses the ability to flow and be shaped, which is why it exhibits a cobweb-like texture when manipulated.