Which factor decreases the working time of a gypsum product?

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Multiple Choice

Which factor decreases the working time of a gypsum product?

Warmer mixing water speeds the setting reaction of gypsum, so it shortens the period during which the material remains workable. When the water is hot, the hydration of calcium sulfate hemihydrate to dihydrate happens more quickly, leading to a faster hardening process. That’s why increasing water temperature decreases working time. If you used cooler water, the reaction slows and you’d have more working time. Adding sugar to water acts as a retarder and would delay setting, increasing working time rather than decreasing it. Changing the powder amount alters the mix ratio and can affect viscosity and final strength, but it doesn’t produce the direct, predictable decrease in working time that warmer water does.

Warmer mixing water speeds the setting reaction of gypsum, so it shortens the period during which the material remains workable. When the water is hot, the hydration of calcium sulfate hemihydrate to dihydrate happens more quickly, leading to a faster hardening process. That’s why increasing water temperature decreases working time.

If you used cooler water, the reaction slows and you’d have more working time. Adding sugar to water acts as a retarder and would delay setting, increasing working time rather than decreasing it. Changing the powder amount alters the mix ratio and can affect viscosity and final strength, but it doesn’t produce the direct, predictable decrease in working time that warmer water does.

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