Frequently Asked Questions

How does the self-sealing property of Conplast Crystalline work in practice?

When a micro-crack forms in crystalline waterproofed concrete and water enters the crack, the moisture activates the dormant active chemicals in the concrete adjacent to the crack. These chemicals react with the calcium hydroxide in the surrounding cement matrix and with the silica compounds in the admixture to precipitate new insoluble hydrated calcium silicate crystals. The crystals grow within the crack, gradually filling the void and blocking the water pathway. The process continues as long as moisture is present. As the crack seals and moisture no longer reaches deeper into the crack, crystal growth stops. If the crack reopens due to further structural movement, the process begins again. This is the basis of the self-healing or self-sealing claim for crystalline technology — the repair is autonomous and requires no human intervention.

Does Conplast Crystalline eliminate the need for a waterproof membrane in basement construction?

Conplast Crystalline can form the primary waterproofing system for below-grade concrete in many basement and underground structure applications, replacing the conventional sheet membrane. However, the choice between integral crystalline waterproofing and a sheet membrane (or a combined system) depends on the hydrostatic head, the structural design (particularly the width of designed crack widths in reinforced concrete), the criticality of the structure, and the risk tolerance of the owner. For high-hydrostatic-head situations (greater than 10 metres of water head) or structures where any water ingress is unacceptable (data centres, archives, critical facilities), a belt-and-braces approach with both integral crystalline waterproofing and a sheet membrane provides the highest reliability. Consult Space Arc Engineering for project-specific waterproofing system selection.

Can Conplast Crystalline be used as a surface-applied treatment as well as an integral admixture?

Yes. The Fosroc crystalline waterproofing system can be applied either as an integral admixture (Conplast Crystalline added to the concrete during mixing) or as a surface-applied slurry (a cementitious slurry containing the active crystalline agents brushed onto the hardened concrete surface). For new construction, the integral admixture approach is preferred as it waterproofs the full depth of the section. For remedial waterproofing of existing concrete structures from the positive (wet) or negative (dry) face, a surface-applied crystalline slurry (such as the Fosroc Brushbond Crystalline product) can be used. The two approaches can also be combined for maximum performance in critical applications.