Page 346 - Construction Waterproofing Handbook

8.6 CHAPTER EIGHT
Destructive testing
Destructive testing involves actual coring (Fig. 8.4) or removal of substrate portions for
testing and inspection. Examples include removing portions of a window wall to inspect
flashings and surrounding structural damage, and removing small mortar sections from a
joint to test for compressive strength. Destructive testing is required when the extent of
damage is not visually determinable or when deterioration causes are inconclusive from
visual or nondestructive testing.
The most frequently used testing includes laboratory analysis of a removed envelope por-
tion. Testing can consist of chemical analysis to determine if materials meet industry stan-
dards or project specifications. Testing can also determine tensile and compressive strength
and extent of contamination by chemical or pollutant attack (e.g., by sulfites or chlorides).
Destructive testing includes probing of substrates by removing portions of building
components to inspect damage to anchoring systems or structural components. Any
removed envelope components should be reinstalled immediately upon completion of
analysis, to protect against further damage by exposing components to direct weathering.
Probing is also completed using a borescope. This equipment allows an operator to
1
view conditions behind facade materials through a borehole only 2 in. in diameter. The
borescope comes equipped with its own light source, allowing close-up inspection without
removal of surrounding components or facing materials. (See Fig. 8.5.)
In-place testing is also used frequently, especially in stress analysis. Stress gages are
installed at cracked or spalled areas, after which a wall portion adjacent to the gage is
removed. Stress readings are taken before and after wall removal, to determine amounts of
strain or compression stress that were relieved in a wall after removal.
This test is helpful in such areas as building corners, to determine if shelf angles are con-
tinuous around corners. These are areas in which stress buildup is likely to occur, resulting
in settlement or stress cracking due to excessive loading.

CAUSE DETERMINATION AND METHODS OF REPAIR

Analysis of compiled information from inspection results and any related data or docu-
ments are usually sufficient for a professional to determine leakage causes and the extent

FIGURE 8.4 Destructive coring of concrete substrate for investiga-
tion. (Courtesy of Webac)