SCP Tech Brief: Waterproofing Concrete: One-time vs Topical Treatments View PDF Download

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Most waterproofing sealers can be grouped into two categories: topical and penetrating. Before examining treatment options, however, the difference between waterproofing and dampproofing should be established. The American Concrete Institute (ACI) Terminology Committee (TAC 90-02) has changed the definitions of these terms:

Waterproof: an idealized property of a material indicating imperviousness to water in either liquid or vapor state. ¹

Dampproof: a treatment of concrete or mortar to retard the passage or absorption of water or water vapor either by application of a suitable coating to exposed surfaces, or by use of a suitable admixture or treated cement, or by use of a preformed film such as polyethylene sheets placed on ground before placing a slab. ²

ACI has limited the use of waterproofing so that products now fall under the dampproofing descriptor, but most product manufacturers are still using “waterproofing” to describe their products. Spray-Lock Concrete Protection (SCP) utilizes the terms “waterproofing” and “dampproofing” interchangeably to facilitate fair comparison of product performance.

Topical sealers, which include acrylics, epoxies and polyurethanes, form protective barriers on top of the concrete surface. Some of the common issues when applying protective film sealers are surface traffic and proper application. Acrylic and epoxy sealers require regular maintenance because both have a high wear potential. Polyurethane sealers are thicker, with a durable abrasion-resistant finish, but they cannot have any water on the surface during application. Additionally, with all topical sealers, reapplication is required when removing flooring placed over a sealed surface.

Then there are the penetrating sealers, which include silanes, silicates, siliconates and siloxanes. These sealers penetrate the top surface of the concrete and react within the bleed water capillaries of the concrete to stop the migration of moisture and deicing chemicals. These products also create problems when installing floor covering systems, as ASTM F710 requires them to be removed from the surface prior to installation.

SCP products also penetrate the surface, but work differently than other sealers. Colloidal silica chemically reacts with the available alkali in concrete to create calcium silicate hydrate (C-S-H), blocking capillaries and pores and chemically stabilizing the pH within. SCP is a one-time treatment that penetrates the concrete matrix, reducing water migration levels to an acceptable range for most coatings, adhesives and floor coverings. Within the interaction zone of SCP, the concrete becomes permanently dampproofed for the life of the concrete. Unlike topical treatments, SCP does not wear away or need to be reapplied. SCP Treatment also provides many additional benefits, including reducing drying shrinkage up to 91% and vapor transmission up to 88%.