Masonry Magazine June 1994 Page. 23
Fig. 4. Avoid spreading mortar too far ahead of units. Place unit on mortar bed within one minute of speading mortar.
severe effects of hot, dry, windy weather. Also covering walls immediately after construction will slow the rate of loss of water from the masonry. Damp-curing (either covering to keep moisture in the wall, fog spraying to replace moisture lost by evaporation, or both) is very effective, and helps development of tensile bond strength. Damp curing should be considered in applications where bending stresses may be significant.
Summary
Advanced planning and preparation are key to the successful construction of masonry in hot weather. Important elements to consider in developing such plans:
* Schedule construction to avoid hot, midday periods.
* Select workable, water-retentive mortar mixes.
* Minimize exposure of materials and equipment to direct sunlight.
* Use cool water to mix mortar.
* Maintain sand piles in damp, loose condition.
* Flush metal equipment and wooden mortar boards with cool water before contact with fresh mortar.
* Pre-wet high IRA clay masonry units.
* Don't spread mortar too far ahead of work. Place top unit on mortar bed as quickly as possible. ACI 530.1 stipulates: "...do not spread mortar beds more than 4 ft (1.2 m) ahead of masonry. Set masonry units within one minute of spreading mortar."
* Under extreme drying conditions, use windbreaks, fog sprays, or wall coverings to assure adequate moisture for curing of mortar.
References
1. Building Code Requirements for Masonry Structures (ACI 530-92/ASCE 5-92/TMS 402-92), Specifications for Masonry Structures (ACI 530.1-92/ASCE 6-92/TMS 602-92), Commentary on Building Code Requirements for Masonry Structures (ACI 530-92/ASCE 5-92/TMS 402-92), and Commentary on Specifications for Masonry Structures (ACI 530.1-92/ASCE 6-92/TMS 602-92), American Concrete Institute, Detroit, American Society of Civil Engineers, New York, and The Masonry Society. Boulder, Colorado, 1992.
2. Panarese, W. C., Kosmatka, S. H., and Randall, F. A., Jr., Concrete Masonry Handbook for Architects, Engineers, Builders, EB008M, Portland Cement Association, 1991, pp. 121-123.
Related Publications
Readers of this publication may also be interested in the following publications available for purchase from the Portland Cement Association. A complete listing of PCA publications is given in the free PCA Catalog (MS254G). To order, write or call Order Processing, Portland Cement Association, 5420 Old Orchard Road, Skokie, Illinois 60077-1083, phone 708/966-6200.
Concrete Masonry Handbook, EB008M
Masonry Mortars, IS040M
Masonry Cement Mortars, IS181M
Air Content and Water Penetration of Masonry Walls, IS191M
Water Penetration Tests of Masonry Walls, IS219M
Building Weather-Resistant Masonry Walls, IS220M
SpecData: Masonry Cement, IS238M
Trowel Tips: Efflorescence, IS239M
Trowel Tips: Tuckpointing, IS240M
Trowel Tips: Mortar Sand, IS241M
Trowel Tips: Field Testing Masonry Mortar, IS242M
Selecting and Specifying Mortar and Grout for Unit Masonry, IS275M
Compressive Strength of Masonry, IS276M
Recommended Practices for Laying Concrete Block, PA043M
Masonry Cement: Beauty to Last a Lifetime, PA163M
Masonry Cement Mortars - A Laboratory Investigation, RD095T
Factors Affecting Water Penetration of Masonry Walls, RP316M
A Homeowner's Guide to Building with Concrete, Brick, and Stone, SP038H