Page 104 - Construction Waterproofing Handbook

BELOW-GRADE WATERPROOFING 2.67

FIGURE 2.85 Clay sheets installed under horizontal concrete slab; note the waterstop installed in the cold
joint. (Courtesy of Coastal Construction Products)

TABLE 2.8 Material Properties of Clay Systems

Advantages Disadvantages
Self-healing characteristics Clay subject to hydration before backfilling
Ease of application Not resistant to chemical in soil
Range of systems and packaging Must be applied in confined conditions for proper
swelling conditions

CLAY SYSTEM APPLICATION

Natural clay waterproofing materials require the least preparatory work of all below-grade
systems. Concrete substrates are not required to be cured except for rubberized asphalt
combination systems. Concrete can be damp during installation, but not wet enough to
begin clay hydration.
Large voids and honeycombs should be patched before application. Minor irregularities
are sealed with clay gels. Most concrete curing agents are acceptable with clay systems.
Masonry surfaces should have joints stricken flush. Note the standard application details
in Figs. 2.87, 2.88, and 2.89.
Bentonite materials combined with butyl rubber require further preparation than other
clay systems, including a dry surface, no oil or wax curing compounds, and no contami-
nants, fins, or other protrusions that will puncture materials.