ST-536 Poly-Roc Void Filling Foam

ST-536 Product profile summary
Stratathane ST-536 Poly-Rok Void Filling Foam is a two part, solvent-free, MDI-based void-filler and stabilization system. ST-536 Poly-Rok is hydrophobic, and reacts with ST-537 to form a strong, light weight, rigid foam. Stratathane ST-536 contains no measurable amount of TDI as performed by the Modified Analysis for Diisocyanates. ST-536 is non-flammable, non-carcinogenic, and non-corrosive as defined by 40 CFR and as described in the NIOSH Pocket Guide for Hazardous Materials.

Stratathane ST-536 Poly-Rok is mixed with ST-537 at the work site to become a single injection material. The inert end product forms a water barrier which is essentially unaffected by acids, gasses, and organisms usually found in soil. Stratathane ST-536 Poly-Rok is useful for a wide range of water control and void filling applications in tunnel and shaft construction and the filling of tanks, pipes, and other subgrade structures prior to their retirement from service. Poly-Rok also may be used to prepare floatation systems in the field because of its very light weight and high percentage of closed cells.

Stratathane ST-536 may be placed by hand pumps or multi-ratio power pumps. Stainless steel fittings are recommended but not strictly required because ST-536 is no more corrosive than water. Cleanup of solidified material in the injection system, however, is often accomplished with caustic cleaning compounds, making stainless steel advisable.

The low viscosity of ST-536 makes it easy to inject. Once cured, its impermeability makes it an effective water shut-off system. The permeability of soil grouted with ST-536 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 three stage reaction takes place when ST-536 mixes with ST-537 and foams. The mixture first thickens in about 15 seconds and becomes creamy. Then, carbon dioxide gas evolves rapidly and the mixture expands as it cures. The expanded volume then sets into a strong impermeable water barrier in about 60 seconds. Unrestrained foam may expand up to 20 times its starting volume depending upon the degree of confinement applied to the expanding mass. ST-536 contains non-volatile materials making up almost 100% of its total weight. Cured ST-536 is very firm. Its solid is a three dimensional cross-linked molecular structure which is insoluble in water.

Set time is the period from first contact of ST-536 with ST-537 to the point where the mix becomes too thick for gravity flow. The set time (sometimes called foam time) is influenced primarily by the mix temperature and the ratio of ST-536 and ST-537. Set times are longest at low temperatures and vary a little with the age of the resin and mineral content of the water. The viscosity of mixed ST-536 is lowest for the first 40% to 50% of the set time and increases rapidly as the mix approaches set.

ST-536 should not stand in equipment more than 12 hours without precautions because of the possibility of moisture contamination. Flush equipment with ST-590 purging fluid and ST-522 Cleaner soon after use. Alternatively, purge grout fluid from pumps and hoses with ST-592 grout purging fluid. The most common solvent for removal of liquid ST-536 is methylene chloride. Check solvents for water content prior to use in long hoses.ST-536 ES is essentially identical to ST-536 except that its set time has been extended to provide more time for placement.

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