Slow setting may be caused by which of the following conditions?

Slow setting may be caused by which of the following conditions?

• A. Prolonged cold weather when protection is not provided to keep the concrete warm
• B. Prolonged hot weather
• C. Too much cement in the mix
• D. Rapid curing with excessive moisture loss

Answer: (A)

Setting time is driven by how fast cement hydrates, and hydration slows dramatically as temperature drops. In prolonged cold weather, the concrete loses heat and stays at a low temperature, so the chemical reactions that turn cement into a solid occur more slowly. Without protection to keep the mix warm, the internal temperature remains low long enough to noticeably delay both the initial and final set, producing slow setting. In contrast, hot weather tends to speed up hydration and set times; excessive cement can raise heat of hydration and also accelerate setting; rapid curing with moisture loss can cause surface drying and cracking but not slower set. So the scenario of extended cold with no warming protection best explains slow setting.

Setting time is driven by how fast cement hydrates, and hydration slows dramatically as temperature drops. In prolonged cold weather, the concrete loses heat and stays at a low temperature, so the chemical reactions that turn cement into a solid occur more slowly. Without protection to keep the mix warm, the internal temperature remains low long enough to noticeably delay both the initial and final set, producing slow setting.

In contrast, hot weather tends to speed up hydration and set times; excessive cement can raise heat of hydration and also accelerate setting; rapid curing with moisture loss can cause surface drying and cracking but not slower set. So the scenario of extended cold with no warming protection best explains slow setting.