Crystalline waterproofing is a treatment that reacts with moisture inside concrete to grow tiny crystals. The crystals fill pores and hairline cracks and make the concrete itself resist water.
How Crystalline Waterproofing Works
Crystalline products contain reactive chemicals that travel into the concrete with water. They react with free lime and minerals to form needle-like crystals. These crystals fill capillary pores and fine cracks, which blocks water from passing through. Because the process needs moisture, the concrete keeps sealing itself if it gets wet again.
Surface Applied vs. Admixture
Crystalline waterproofing comes in two forms. A slurry coat is brushed or sprayed on cured concrete, and an admixture is added to the concrete at the batch plant. Slurry coats are used to fix existing structures. Admixtures are planned ahead on new pours such as foundations, elevator pits, and water tanks.
Crystalline vs. Membrane Waterproofing
A membrane sits on top of the concrete as a film and can fail if it is punctured or loses bond. Crystalline treatments are part of the concrete, so they cannot peel. They do not bridge large moving cracks, though. Wide or active cracks still need injection or a flexible membrane.
Practical Tips for Crystalline Waterproofing
Open the pores first by blasting or scrubbing the surface, and pre-wet the concrete so it is damp but has no standing water. Apply at the coverage rate on the data sheet and keep the coating damp for the cure time listed. Repair active leaks and large cracks before you apply, and check whether a later coating is compatible.
Also Called
Crystalline admixture, Penetrating waterproofing
