Chemical grouting is a broad term for using non-cementitious grouts, such as acrylates, prepolymers, resins and solution grouts which do not contain cement, for various uses such as soil strengthening and water control.
Because chemical grouts are lower viscosity and slower reacting then most plural component polyurethanes, they excel in seeking out and sealing small water passages. This includes the void space between soil particles and cracks in structures. Chemical grouts can also be used to increase the bearing capacity of weak soils by binding soil grains together. If water is passing trough soil, very low viscosity chemical grout can be used to significantly reduce soil permeability.
Permeation grouting generally refers to using chemical grouts to increase soil strength. Permeation grouting involves saturating soils with grouts which bind soil particles together in order to increase their bearing capacity, reduce their ability to erode, or otherwise change their physical characteristics.
Types of Chemical Grouting Materials
There are many types of chemical grouts. CJGeo mostly installs prepolymer grouts (expansive) and acrylic grouts (non-expansive).
Prepolymer Chemical Grouts
We install prepolymer chemical grouts, which are expansive. Expansive chemical grouts react with moisture in the soil or environment and expand up to 30 times. This allows them to cut off fast-flowing water, and treat larger volumes of soil per gallon than non-expansive grouts, such as acrylics.
Prepolymer grouts can be highly expansive or low expansion. Catalyst/accelerator dosing is used to control reaction profiles in the field. Soil characteristics, ambient temperatures, volume of leaks, and velocity of the water flow being stopped all impact grout set time selection.
Acrylics, such as acrylate and acrylamide, are non-expansive grouts. Acrylic grout is mostly water, so is very low viscosity. Soils treated with acrylics tend to have lower strengths than soils treated with prepolymers, so facilitate future excavation.
CJGeo uses acrylate grouts, which are non-toxic, and cure to a consistency similar to a cooked egg white at high dilution, and a silicone rubber consistency at lower dilutions. The set time of acrylate grout is adjustable in the field by adjusting dosing of catalysts.
Plural Component Polyurethanes
Plural component geotechnical polyurethanes are occasionally considered a type of chemical grout. CJGeo’s CJGrout geotechnical polyurethanes are sometimes used in place of chemical grouts, but have significantly different physical properties. They are highly expansive, rigid, do not require environmental moisture, and the only reaction is between the two components of the grout themselves.
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