There are two main field testing methods used for water repellency of concrete masonry units (CMUs), for quality assurance before being placed in a wall: droplet and RILEM tube testing. Completed assemblies can also be tested with RILEM tubes or other standard water spray tests such as ASTM E514, Standard Test Method for Water Penetration and Leakage Through Masonry.
A single-wythe concrete masonry wall may be a cost-effective structural element, but it can present challenges for waterproofing. The National Concrete Masonry Association (NCMA) recommends redundancy to keep concrete masonry walls dry through techniques at the surface of the wall, within the wall, and through adequate drainage systems. Unfortunately, many concrete masonry wall designs rely solely on admixtures in the concrete masonry units (CMUs) and mortar and surface-applied water repellents. However, low absorption values do not guarantee water penetration resistance; this disconnect in the industry is a leading reason for leakage in single-wythe concrete masonry walls.
A material’s thermal mass denotes its ability to store heat within a cycle of time. K-values, generally calculated on a 24-hour cycle, are important because they give general references to a material’s capabilities for storing heat. All materials may be considered for use in a thermal mass calculation, but steel, aluminum, and other metal claddings tend to cycle too quickly, while wood tends to cycle too slowly to offer desirable design values.
The 2012 International Energy Conservation Code (IECC) will bring tremendous change to the way buildings are designed, constructed, and renovated. For example, the insulation requirements for masonry construction have been written to higher performance levels. The prescriptive energy code for the masonry industry is based primarily on the requirement for continuous insulation (ci) within the wall envelope. This becomes an issue when one looks at the standard concrete masonry unit.
In a time of increasing complex walls, the masonry industry is striving to rediscover the simplistic principles that made it the material choice of the greatest civilizations in history. The principle “less is more” holds true when it comes to selecting wire reinforcement for reinforced masonry wall systems. Standard 9 gauge ladder shape wire fabricated with butt-welded cross-rods spaced 16 inches on center better facilitates code required rebar centering, grout flow and consolidation, and shrinkage control.