2.13 : Masonry in Cold and Hot Weather Conditions

In cold weather, masonry construction requires specific precautions to ensure mortar does not freeze before curing, as this can significantly weaken its strength and watertightness. Mortar temperature should be maintained between 60°F and 80°F to support proper hydration and curing. Below 40°F, mortar water must be heated, but should not exceed 120°F as high temperatures can reduce mortar's compressive and bond strength.

Other key practices include keeping masonry units and sand dry and protected from freezing temperatures, using heated sand to maintain mortar at an optimal temperature, and using Type III cement for faster curing. Mortar should be mixed in small batches to prevent cooling, and masons' workstations should be shielded from the wind and heated if necessary. Newly laid masonry needs protection from freezing for at least a day, and surfaces should be covered to shield against rain and snow.

In hot weather, the challenge is preventing mortar from drying too quickly. Masonry units may need dampening before use to prevent excessive water absorption from the mortar. Keeping masonry units, mortar ingredients, and workstations shaded helps manage this. Often, masonry is treated with a fog spray and then covered with weather-resistant membranes to shield it from sunlight at the end of the day.