How do extreme temperatures affect mortar curing and what steps can be taken to protect it?

• A. Cold temperatures speed up curing; use fans to cool.
• B. Cold temperatures slow cure and can cause freezing; use heaters, blankets, curing compounds, and protect from wind.
• C. High temperatures always cause rapid curing; ignore protective measures.
• D. Temperature has no effect on mortar curing.

Answer: (B)

Cold weather slows mortar hydration and can allow water in the mix to freeze before the mortar gains strength, leading to cracking and a weaker bond. To protect it, raise and maintain the temperature around the mortar with heaters or heated enclosures, cover with insulating or curing blankets to trap heat and moisture, apply a curing compound to seal in moisture, and shield the work from wind to reduce evaporation. If possible, use warm water for mixing and keep the mortar covered and protected during the initial curing period until it gains sufficient strength.