Page 95 - Construction Waterproofing Handbook

2.58 CHAPTER TWO

FIGURE 2.73 Applying reinforcement strips at transition
details. (Courtesy of TC MiraDRI)

FIGURE 2.74 A column foundation waterproofing detail. (Courtesy of Grace Construction Products)

expansive sheets that can expand massively. The amount of swelling and the ability to
resist water is directly dependent on grading and clay composition. Clay swells 10–15 per-
cent of its dry volume under maximum wetting. Therefore, it is important to select a sys-
tem high in montmorillonites and low in other natural sediments.
Bentonite clay is an excellent waterproofing material, but it must be hydrated properly
for successful applications. Clay hydration must occur just after installation and backfill-
ing, since the material must be fully hydrated and swelled to become watertight. This
hydration and swelling must occur within a confined area after backfill for the waterproofing