ST-520 Poly-Foam Injection Resin

ST-520 Product profile summary
Stratathane ST-520 Poly-Foam is a hydrophilic, single component, flexible polyurethane resin based on TDI for sealing leaks in concrete and masonry structures. ST-520 Poly-Foam reacts with water, expands, and then sets into a flexible closed-cell foam. ST-520 contains about 15% acetone and has a sweet, solvent-like odor. The acetone lowers viscosity and assists in distributing the available water through the resin. ST-520 is essentially non-toxic in its cured form.

ST-520 is usually injected directly from the can into the leak using either a single or a plural component pump. ST-520 creates an elastic seal that stops water entry but allows crack movement to protect against stress transfer. The cured material exhibits excellent adhesion to concrete and is not corrosive. At 70 F, reaction time is approximately 30 seconds and cure time about two minutes. It has no preset Apot life@ and does not cure as long as water or moisture vapor are not available to start the cure cycle.

A two-stage reaction takes place when ST-520 comes in contact with water. The mixture first expands and thickens. Then, as it cures, ST-520 quickly solidifies into a strong impermeable water barrier in just minutes. Unrestrained ST-520 foam expands up to ten times its starting volume. However, a dense material is preferred for most applications. Greater density is obtained by controlling grout placed relative to void space and static head pressure. ST-520 is rated high in its ability to tolerate freeze-thaw, wet-dry cycling, extrusion, and compression.