In a building landscape where the expected lifespan of a structure is longer than usual, the durability of the materials that encompass the structure become more critical. Sustainability is key for any structures 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 molded or formed into virtually any shape when freshly mixed and, when hardened, becomes a strong and durable material capable of a long lifespan.
In most instances, deterioration of concrete is due to a lack of adequate durability, rather than deficient strength. Concrete structures can become unserviceable due to gradual weakening arising from concrete deterioration and steel corrosion. Reducing concrete deterioration by increasing its durability has become a challenging problem facing the industry.
In most every case of concrete degradation, the root cause of the issue is the presence of moisture or water within the concrete. The ingress of deleterious substances into concrete takes place 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.
Surface Applied Membranes
As is the case in business, there are often several options to choose from; concrete waterproofing is no different. One of the
options available on the market is an external surface-applied membrane. 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 limitations:
External membrane failure can occur in a number of different situations, most as a result of design errors, installation mistakes, or material limitations and defects. This is why simplifying the process by making the concrete itself serve as the waterproofing barrier can prove valuable for a project.
Integral Crystalline Waterproofing
Integral Crystalline Waterproofing (ICW) prevents the movement of water through the concrete by plugging or blocking the
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.
The Science
ICW technology is based on principles that are very similar to the processes that occur during concrete hydration. When ICW products are added or applied to concrete, crystalline chemicals facilitate a reaction that causes long, narrow crystals to form, filling the pores, capillaries and hairline cracks of the concrete mass. As long as moisture remains present, crystals continue to grow throughout the concrete. Once the concrete has dried, the crystalline chemicals sit dormant until another dose of water (such as through a new crack) causes the chemical reaction known as crystallization to begin again.
The ability to reactivate in the presence of water gives crystalline-treated concrete the ability to improve self-sealing. When cracks form due to drying shrinkage, settling, seismic activity, etc., water entering through them causes new crystals to form and grow, blocking and filling the cracks. Improving the self-sealing ability of concrete is one of crystalline technology’s most unique and useful features, and can help to dramatically reduce the long-term maintenance and repair costs of a concrete structure.
Main Benefits of ICW
ICW contributes many beneficial properties to a given project, including:
Where Can ICW Be Used
ICW systems have been used in a wide variety of concrete structures across the world. The most common applications include:
ICW has proven to be most effective in areas exposed to high-hydrostatic pressure, such as is found in below-grade foundations and water containment tanks.
What ICW to use?
A number of companies offer integral waterproofing products for new and existing concrete structures. These products have different chemistries and, more importantly, different levels of performance. When selecting Integral Crystalline Waterproofing products, it is important not to confuse them with:
These products are suitable for damproofing or above grade water repellency, but not suitable for below grade waterproofing applications.
An ideal concrete waterproofing system should:
Furthermore, the concrete waterproofing industry redefined their terminology a short time ago. In fact, American Concrete Institute’s (ACI) 212.3R-10 Report on Chemical Admixture document devoted Chapter 15 to Permeability Reducing Admixtures that outlines PRAH and PRAN classifications. Permeability Reducing Admixture – Hydrostatic Conditions or PRAH products are sufficiently able to resist water under hydrostatic pressure penetration and are suitable for watertight construction.
Conversely, damproofing admixtures are now referred to as Permeability Reducing Admixture – Non-Hydrostatic Conditions or PRAN. PRAN admixtures reduce water absorption by repellent chemicals (soap, oils) or partial pore blocking (densifiers). These admixtures are not suitable for concrete exposed to water under pressure and cannot protect in the presence of hydrostatic pressure. Waterproofing against hydrostatic pressure is an important distinction that sets PRAHs apart from PRANs.
Also, select a crystalline waterproofing supplier who can demonstrate a repeated history of long-term success. The manufacturer should offer a long term warranty and have the company history to back it. The manufacturer should be able to provide accredited third party test results and have achieved industry recognized certifications for product quality and performance.
Most importantly, because of the ongoing value of close technical support, be sure to select a product from a manufacturer who has demonstrated the willingness and ability to provide on-site service and support for major projects anywhere in the world.
Conclusion
Integral Crystalline Waterproofing is the future of concrete waterproofing worldwide. With sustainable building practices increasing in importance, and the lifespan of a structure intrinsically connected to this movement, a reliable waterproofing solution that will last for the intended life of the concrete structures becomes very important.
Alireza Biparva, M.A.Sc., LEED Associate, is research and development manager/concrete specialist at Kryton
International Inc. Alireza oversees several research projects focusing primarily on concrete permeability studies and the development of innovative products and testing methods for the concrete waterproofing and construction industries.
He can be reached at alireza@kryton.com.
Source: Structure Magazine
