Water is an essential part of concrete production, pouring and curing. Once the water has helped with those roles, it is no longer helpful to concrete because cured concrete is porous and prone to cracking, which causes it to be vulnerable to water infiltration.
A method for protecting concrete structures from water damage is to make the concrete waterproof. Waterproof concrete is different than coating, sealing or wrapping it to resist water. This method makes the concrete less permeable with admixtures, both Permeability Reducing Admixtures for Non-Hydrostatic conditions (PRANs) and Permeability Reducing Admixtures for Hydrostatic conditions (PRAHs).
Before we talk about the advantages of integral waterproofing, it is important to note that waterproof concrete by itself does not deliver waterproof construction. Water can still go around concrete and penetrate joints, so these entry points will still need attention.
PRANs and PRAHs are also referred to as integral waterproofing. Integral waterproofing has advantages over other methods of waterproofing because it can’t be torn or damaged during backfill. It also won’t delaminate, decompose or wear out, protecting the concrete and reducing long-term maintenance costs. Since it’s integral to the concrete itself, there are no issues with installation and other waterproofing installation problems are eliminated.
PRAH technology blocks water from entering concrete on all sides and it greatly decreases the permeability of the concrete, extending the service life. When moisture is blocked, the rebar within the concrete does not corrode, and the PRAH technology becomes part of the concrete matrix. As the concrete continues to hydrate over time, the admixture crystals grow when they come in contact with water, and they self-seal hairline cracks up to .5 millimeters and damp spots of all diameters.
According to Alain Lok of Kryton International, integral waterproofing of concrete is cost effective. Kryton’s branded material, Krystol Internal Membrane (KIM), ranges from $60 to $80 per cubic yard of concrete depending on the re-seller. The additional cost can be offset by the elimination of typical exterior membranes and the labor required attaching them, which also reduces overall construction time.
PRAHs should be used in below-grade concrete construction. With insulating concrete form (ICF) construction, integral waterproofing can make construction even better.