ACI Concrete Strength Testing Technician Practice Test

The correct understanding hinges on the properties of sulfur mortar and its interaction with moisture. For sulfur mortar, it is essential that it remains free of moisture to prevent foaming. When moisture is present, it can react with the sulfur, leading to the formation of gas and consequently foaming when the sulfur is mixed or heated.

Keeping the sulfur mortar dry ensures that it will not react adversely when added to the mixing pot. In contrast, if the mortar is liquid or heated, it may still contain some moisture, which can trigger foaming. Mixing without ensuring dryness can also introduce air or moisture, increasing the likelihood of foaming. Therefore, ensuring that the sulfur mortar is dry before addition is vital for maintaining the desired performance characteristics and avoiding foaming issues during application.