Make smart concrete: A study on self-sealing

Less than two weeks after the leakage test, the crystals in the admixture self-sealed, leaving zero leaks.
Less than two weeks after the leakage test, the crystals in the admixture self-sealed, leaving zero leaks.

A crystalline waterproofing admixture was therefore specified for the project. After the concrete had set, a newly constructed containment tank was filled with water for a leak test to ensure the crystals in the admixture had begun to take effect. After a week, a significant amount of leakage had stopped, but water still seeped through the structure. The contractor onsite was concerned about a potential delay in project completion and was ready to employ a polyurethane injection to stop the leaks. However, waterproofing consultants onsite advised him to wait, assuring him the crystals would form. If the injection was still necessary after two weeks, they promised to recommend an extension of the deadline.

The proprietary crystals in the admixture did begin to take effect, and the walls were completely devoid of moisture. At the end of the two-week period, the injection was not needed. The crystals, having reacted with the water and unhydrated cement, had self-sealed, blocking all the pathways of water through concrete.

Initially skeptical about the concept of self-sealing, the contractor expressed delight with the final result. He was happy with the savings of time and the elimination of additional expenses for injection repairs.

The interlocking needle-like crystals in the waterproofing admixture will continue to grow and protect concrete from water penetration. Six years after the concrete was first poured, the concrete structure remains durable and waterproof.


The crystalline admixture used in the Newburyport case study will provide waterproofing for the life of the concrete structure and enhance the structure’s durability. When specifying the integral admixtures, it is vital the application instructions are followed correctly and good construction practices are put in place onsite.

Crystalline admixtures can be used with existing mix designs, but advice should be sought from the admixture supplier, especially if the concrete provider has limited experience with such materials. The supplier can also provide recommendations for joint detailing, penetrations, and remedial repairs if cracks form that are too large to self-seal.

Crystalline admixtures are useful while waterproofing foundations, even in regions with a high water table. In fact, any concrete subjected to water pressure can use crystalline admixtures for permanent waterproofing. Waterproofing admixtures can be employed in underground parking structures, tunnels, bridges, marine structures, water containment applications, canals, and elevator pits. Further, they can be used with precast, cast-in-place, and shotcrete applications as they are integral to the concrete. By combining the waterproofing step with the placing of concrete, integral admixtures avoid labor-intensive, costly, time-consuming surface preparation and installation costs. They also have the added benefit of eliminating silica-dust exposure in the workplace.

Crystalline admixtures help transform concrete into a waterproofing barrier and enhance the durability and longevity of structures, thereby contributing toward building a better, more sustainable future.

Alireza Biparva, M.A.Sc., LEED GA, works as research and development (R&D) manager and concrete specialist at Kryton International. He has more than 10 years of experience in the field of concrete permeability. Biparva oversees a variety of research projects on Krystol Technology, focusing primarily on concrete permeability studies and the development of innovative products and testing methods for the concrete, waterproofing, and construction industries. He is an active member of the American Concrete Institute (ACI). Biparva can be reached at

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