Hot Weather Masonry – Protection
General. Increased temperatures result in a decrease in relative humidity at the surface of the masonry and an increase in evaporation rates. These conditions can lead to dry-out of the mortar and grout, which adversely affects their properties.
The use of wind screens has been shown to be effective in protecting against the drying effects of wind during extremely hot weather. Materials commonly used for protection are canvas and synthetic coverings (reinforced polyethylene and vinyl).
Under severe drying conditions, research has shown that the daily application of a fog spray to the surface of the walls for a period of about three days or covering of the walls with polyethylene plastic, or both, dramatically improves flexural bond strength over walls not similarly protected.
The tops of all walls not otherwise protected should be covered with a weather resistive membrane extending a minimum of two feet (0.6m) down on both sides to prevent water from entering the masonry.
Safety. Workers responsible for installing protection should have a full knowledge of the type of wind screen being used, and how to properly erect, adjust, brace, anchor, and dismantle the complete assemblage. Wind screens must be properly erected, braced and anchored so that the assemblage is safe from wind loads and lift. Protection should include measures to safeguard workers from injuries caused by high winds.
Summary. The use of wind screens and moist curing of walls by the use of fog sprays and/or protective coverings, will protect against dry-out of the mortar and grout and help to improve flexural bond strength. Construction of wind screens should take into account consideration of the protection of the masonry structure and the safety of the workers.
Resource: Masonry Institute of St. Louis – www.masonrystl.org
Hot & Cold Weather Masonry-Publication of Masonry Industry Council