Which of the following statements about grouted masonry is correct regarding its placement?

The correct response is that grouted masonry must be placed within a strict time limit. This is crucial because the chemical composition and properties of the grout change as it begins to set after mixing. If the grout is not applied within the specified timeframe, it may not achieve the desired strength or bond once it hardens. The time limit ensures that the grout can adequately fill the masonry units and provide the necessary support.

In contrast, other options do not accurately reflect best practices for grout application. While grouted masonry may be placed at varying temperatures under certain conditions, temperature extremes can significantly affect the curing process and performance, thus making the statement about temperature imprecise. As for placement timing after mixing, it's essential for grouted masonry to be used promptly, negating the option suggesting it can be placed anytime. Lastly, the option referring to a 4-hour undisturbed period might mislead about the proper curing and setting times required for grout to be effective. Proper guidelines recommend that grout is not disturbed until it has adequately set, which is typically much shorter than 4 hours.