EMA Masonry Forensics Services
Some masonry forensics problems are regional, but many occur nationwide. Here’s an overview of 10 common construction problems that masonry contractors face.
Efflorescence in masonry forensics
When water containing dissolved salts evaporates from a masonry structure it leaves a salt deposit (Figure 1). The stain is called efflorescence. Salts may be present in all types of masonry materials: mortar, brick, concrete block, stucco, and plaster. Or they may be in water that enters the masonry.
Besides being unsightly, efflorescence may lead to more serious problems such as cracking. Salt crystals deposited in pores sometime generate enough pressure to crack the masonry.
To prevent efflorescence, prevent water from entering the wall and provide drainage for water that does. Design properly and install flashing, weep holes, drips, and caulking.
Corrosion in masonry forensics
In the presence of water and oxygen, steel rebars in bond beams, grouted cells, or collar joints will corrode. Horizontal joint reinforcement, ties that hold multi-wythe masonry walls together, or anchors that attach a veneer wall to a support also are susceptible to corrosion.
Rust, the product of corrosion, occupies up to six times the original volume of steel. This volume expansion causes cracks that let in more water and thus cause even more corrosion.
The most common materials used for reinforcing are un-coated steel, zinc-coated steel, and hot-dipped galvanized steel. The coatings and the alkaline mortar provide some corrosion protection. There is, however, no substitute for good tight mortar joints and flashing that minimize the amount of moisture entering and accumulating in the masonry.
Also, avoid adding chloride to mortar or grout; soluble chlorides accelerate corrosion. And don’t install dissimilar metals such as copper and steel in the same wall. When there’s moisture in the wall, dissimilar metals sometimes react and cause corrosion too.