Sustainability is key for any structure’s viability in today’s construction world, which means new technologies are of great value to not only the project teams, but also the environment. Concrete is currently the most used humanmade material in the world, used twice as much as all other materials combined. Concrete is used so much because it has a relative low cost, is versatile, has unique engineering properties and its ingredients are widely available. This often makes concrete more attractive to the construction industry than other materials like steel or wood. Moreover, a key advantage to concrete is that it can be melded or formed into virtually any shape when freshly mixed and, when hardened, becomes a strong and durable material capable of a long lifespan. Although hard and dense, it is a porous material which makes it highly susceptible to damage and deterioration from water and chemical penetration. That’s why nearly all commercial and residential concrete projects specify some type of waterproofing system. That’s where integral waterproofing comes in.

-with concrete being porous, in most every case of concrete degradation, the root cause of the issue is the presence of moisture or water within the concrete. Water absorbed can cause reinforcing steel corrosion and concrete spalling, decreasing the buildings lifespan –durability has become a challenging problem facing the industry when it comes to concrete deterioration as problems arise through the pore system in the concrete matrix, or through microcracks. In order to effectively ensure a concrete structure’s durability, which leads to a longer lifespan and a more sustainable building, the concrete must first be effectively waterproofed. concrete can be waterproofed from the positive (wet/exterior) side, negative (dry/ interior) side or from within the concrete itself (integral systems). The oldest and most widely used method is positive-side waterproofing using sheet membranes. The membrane is installed after concrete has hardened to prevent the ingress of water into basements, foundations, walls, and roofs. However, surface applied waterproofing membranes do have a number of issues. It can be expensive, time-consuming, and easy to damage. Most membranes are made using oil-based materials and are not sustainable. If they leak, it’s not obvious who caused the problem and there can be a lot of finger-pointing.

What is integral waterproofing?

Integral crystalline waterproofing is most often a dry powder mix of Portland cement, fine silica sand and a specific (and usually proprietary) blend of chemicals. It is either an admixture added to ready-mixed concrete at the time of batching for in-situ pours or sprayed concrete applications, or a surface-applied mixture used for existing structures. Surface-applied crystalline waterproofing formulas are brushed or sprayed onto existing structures as a slurry coating or spread over and trowelled into freshly poured concrete slabs as a dry-shake treatment. When contact with water, integral waterproofing generates non-soluble crystal throughout the capillaries and pores in the concrete structure creating an impenetrable water barrier preventing the movement of water through the concrete by plugging or blocking the ad natural pores, capillaries and micro cracks, thereby making concrete its own waterproofing barrier. This stands in contrast to more conventional means of waterproofing, which usually involves applying a coating or membrane to the concrete surface. The process is sometimes also attempted through densification of the concrete. The ICW method of concrete waterproofing has been proven effective through successful use in virtually every country in the world.

Types of integral waterproofing

Integral waterproofing products are marketed under a dozen or more different brand names. While the chemical composition of each is slightly different, they all are either densifiers, repellents or crystalline admixtures. Densifiers fill the microscopic pores in the concrete matrix to eliminate water infiltration. Water repellents make the concrete hydrophobic. Crystalline admixtures cause microscopic, water-blocking crystals to seal pores and hairline fractures.

1.Densifiers: Densifiers use pozzolans—usually silica fume or other silicates—to fill the pores in the concrete matrix. Silica fume is an industrial by product created in the refining of silicon metal and its alloys. In its original form, silicone dioxide is extremely fine— about 1/100th the size of the average Portland cement particle—and has the same consistency as cigarette smoke. These particles are captured, condensed, and sold as a concrete additive. Silica fume, because of the extremely fine particle size and the high silicon dioxide content, reacts readily with water and fills the microscopic pores in the concrete. It also adds considerable strength to the mix.

2.Repellents: A newer class of integral waterproofing products work by developing polymer barriers inside pores during the hydration process. The water repellent nature of the polymers can cause water to bead on the surface of the concrete. The surface tension of the water itself keeps it from being able to penetrate the wall. The active ingredient of these admixtures can include stearates, petroleum-derived materials, or water-based materials. This type of integral waterproofing is popular for above-grade work, such as precast cladding panels. A few brands of this type, though, can be used in foundation walls.

3.Crystalline: The third major class of integral waterproofing is crystalline technology. In the presence of water, the ingredients of these products react with calcium hydroxide and other by-products of cement hydration to form non-soluble crystals that fill and plug the pores and microcracks in concrete—even years after it was poured. Crystalline products can be applied in several different ways, but adding it to the mix at the batch plant is the most common. Crystalline admixtures are also self-healing, reacting throughout the life of the concrete structure to automatically seal cracks up to half a millimetre wide. This is especially useful on large concrete pours, as it is enough to waterproof most cold joints with no additional treatment needed. Crystalline waterproofing is also extremely durable, and in laboratory tests have withstood up to 200 psi. That’s 460 feet of hydrostatic pressure. Crystalline waterproofing is preferable to use in any project where the concrete will be subjected to hydrostatic pressure.