ST-530 Quik-Rok Soil Stabilizer

ST-530 Product profile summary
Stratathane ST-530 Quik-Rok Soil Stabilizer is an expanding urethane prepolymer grout which reacts with water and sets into a rigid, closed-cell foam. ST-530 is mixed with ST-531 at the work site to form a single injection material whose reaction time with water is governed by the concentration of ST-531. Some water is needed for reaction, but large amounts can be handled by displacement. The inert end-product forms a water barrier which is essentially unaffected by acids, gasses, and micro-organisms usually found in soil.

ST-530 is useful for a wide range of water control and soil stabilization applications. ST-530 has been effective in forming grout curtains, in stabilizing water bearing soils, and as a locking agent for rock anchors. ST-530 may be placed by hand pumps or multi-ratio power pumps. Stainless steel fittings are recommended but not strictly required because ST-530 is not caustic. Caustic cleaning compounds, however, may make stainless steel advisable.

The low viscosity ST-530 mixture is easily injected. Once cured, its impermeability makes it an effective water shut-off system. The permeability of soil grouted with ST-530 depends on how well its voids are filled with grout. Values in the 10-7 cm/sec range should be obtained using ASTM Constant Head Permeability Test Method D-2434.

A two stage reaction takes place when ST-530 meets water. The mixture first expands and thickens. Then, as it cures, it quickly solidifies to a strong impermeable water barrier. Unrestrained (Free- Foamed) ST-530 expands up to 15 times, with a final foam density of about 27kg/m“. However, a dense material is preferred for most applications. Greater density is obtained by controlling the amount placed relative to void space and static head pressure.

The reaction takes place continuously during injection as product exits the packer. Initial penetration is facilitated by the low viscosity of the mixture. After reaction begins, the expansive mixture pressure may induce further penetration. ST- 530 creates a seal which is impervious to water yet tolerates freeze-thaw, wet-dry, extrusion, and compression.

Uncured ST-530 is a dark brown liquid with a viscosity of about 140 cps at 25 C (77 F). This low viscosity is further reduced after addition of ST-531. ST-530 contains non-volatile materials making up almost 100% of its total weight. Cured ST-530 is semi-rigid. Its solid is a cross-linked molecular structure which is insoluble in water.

Set time is the period from contact of ST-530 with water to the point where the mix becomes too thick for gravity flow. Set time is influenced primarily by the mix temperature and the ratio of ST-530 to ST-531. Set times are longest at low temperatures and ST-531 ratios and vary a little with resin age and water mineral content. Mix viscosity is lowest for the first 30% of the set time and increases rapidly as the mix approaches set. As a rule of thumb, one ounce of ST-530 will be needed per 2 cubic inches of void, but considerable variance is possible. Application techniques can minimize quantity while maintaining seal quality. The advice of an experienced contractor is very helpful. The main factors affecting quantity are the grout method used, void size to be filled, penetrability of the grout zone, water flow volume and velocity, and the type of equipment used.

ST-530 should not stand in equipment more than 12 hours because the possibility of moisture contamination is high. Flush equipment with solvent and cleaner soon after use. The most common solvent for removal of liquid ST-530 is ST- 590 or methylene chloride. Check solvents for water content prior to use. When using solvents during cleanup, observe proper precautions for handling such materials. For cleanup of cured ST-530, soak in a 100% solution of ST-522 cleaner using a covered polyethylene container. Grout spills on clothing are permanent, so disposable coveralls are recommended.

ST-530 is sensitive to high storage temperatures. Under optimum storage of 40 - 60 F in dry conditions, the material should have a useful shelf life of more than one year. Storage temperature should not exceed 80 F. Once a container has been opened, the life of the material is reduced. Let container stand and adjust to ambient temperature before opening to prevent contamination by condensation. Reseal opened containers as quickly as possible. Prior to use, carefully test a resealed container to assure that moisture contamination has not occurred. Do not seal any container of ST-530 to which ST-531 has been added because condensation or moisture in the air may cause a reaction leading to rupture of the container.