NOH2O® is a Polymer-Based Emulsion (PBE) grout first developed in the 1970s. PBE is a suspension of colloidal polymer emulsoids dispersed in a solution of additives promoting flow and adhesion.
PBE is a non-Newtonian, dilatant fluid; it sets by internal shear as the grout passes through fractures or other voids in water-bearing media. Set time may also be controlled chemically with the use of activator or inhibitor to regulate spread. Still, PBE is differentiated from solution grouts, because it is a single part grout whose set does not require a chemical reaction. The tendency for PBE to set when agitated renders it useful in turbulent, high velocity flow situations where other types of grout will suffer dilution and washout.
NOH2O® PROPERTIES
- Particle size < 1 micron.
- Viscosity at point of injection = 1.5 centipoise.
- Single part and miscible in water.
- Wash-out resistant under high flow/high pressure conditions.
- Controlled curing rates from 2 seconds to several days.
- Sets effectively in saline and hypersaline formation waters.
- Remains flexible after solidification. 350%+ Elasticity.
- Ultimate Tensile Strength ≈ 5 MPa
- Specific Gravity ≈ 0.97
- No adverse effects from freezing after curing
- No adverse effects from geothermal water
- Curing is non-exothermic and non-expansive.
- Safe to handle and environmentally friendly. Not classified as Dangerous Goods according to OSHA regulations.
- Radiation resistant
- 100+ year design life
Given its low viscosity and small particle size, PBE can penetrate and seal water in fine fractures. NOH2O® has successfully sealed discrete inflows as high as 2600gpm (165l/s) at pressures up to 2900psi (20MPa).
Differences Between NOH2O® and Solution Grouts
PBE is an emulsion as opposed to a chemical or solution grout. A major difference between PBE and resinous solution grouts is in how the material sets from a fluid to a solid grout mass. Most resinous grouts require a chemical reaction between an agent and a reagent to set. Required reactions may be between a chemical solution and water, or between two to four components pre-mixed or injected simultaneously. In contrast, PBE can set solely by mechanical means; no chemical reaction is necessary. Because PBE activation can be achieved without a chemical reaction, grout set is non-exothermic.
The key difference/advantage of NOH2O® over resinous chemical grouts is how the desired set time is achieved. Set time for chemical grouts must be pre-determined and achieved by mixing a set proportion of catalyst in the resin prior to injection. Because PBE can be used as a single-component, self-activating grout, the need for a pre-determined set time is not necessary. Instead, set time is controlled based upon real-time field observations indicative of flow patterns/behavior in a geologic formation or behind a liner system at any desired injection rate.
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