Frequently Asked Questions

What is the difference between Nitofill WS60 and Nitofill PU1F for waterproofing injection?

The key difference is the cured product form and the intended application. Nitofill PU1F is a water-reactive polyurethane foam resin — it reacts rapidly with water to produce expanding foam, generating large volume increases (10 to 30 times) that physically block actively flowing water leaks. It is an emergency stop for flowing leaks. Nitofill WS60 is a hydrophilic polyurethane gel resin — it reacts with water to form a flexible, impermeable gel without significant expansion. It is used for permanent sealing of static (non-flowing) cracks and joints where a long-lasting, flexible, waterproof seal that accommodates minor movement is needed. The PU1F foam is the stop-the-leak solution; WS60 is the permanent sealing solution for stable cracks and joints.

How is the hydrophilic swelling of Nitofill WS60 beneficial for crack sealing?

When cured Nitofill WS60 gel in a crack is wetted by water, the hydrophilic polymer swells. This swelling causes the gel to expand slightly within the crack, pressing against the crack faces and improving the contact between the gel and the concrete surface. Any minor reopening of the sealed crack (due to temperature change, slight structural movement, or reduced confining stress) is compensated by the swelling of the gel in the presence of water — the gel swells to fill the additional space opened by the movement. This self-adjusting swelling behaviour is the key advantage of hydrophilic polyurethane over rigid epoxy (which cannot accommodate any movement) and over hydrophobic polyurethane foam (which is already expanded and cannot swell further). In permanently wet conditions (such as below the water table), the hydrophilic gel maintains its seal as long as water is present.

Can Nitofill WS60 be used for pre-injection (preventive injection) of construction joints before the structure is water-loaded?

Yes. Pre-injection of construction joints with Nitofill WS60 before the structure is exposed to hydrostatic pressure is an effective preventive waterproofing technique for critical water-retaining structures. The injection ports are installed in the joints during construction, and the resin is injected and allowed to cure in dry conditions before the structure is filled or the basement is backfilled and subjected to groundwater. This ensures the joints are sealed before any water pressure is applied. The hydrophilic character of the cured gel means it maintains its sealing properties when the joint later becomes wet from the hydrostatic head, and even swells slightly to improve the seal. Pre-injection is recommended for critical construction joints in water treatment plants, tunnels, and basements with high groundwater tables.