Injection grouting is the process of pumping grout under pressure to fill voids, correct settlement, or control water. Most of the time, “injection grouting” is interchangeable with “chemical grouting”. However, injection grouting is sometimes used more broadly to include injection of cement-based grouts, such as CJFill cellular concrete.
Void Filling
Plural component polyurethane grouts, such as CJGrout geotechnical polyurethanes are great for void filling. Plural component polyurethanes are highly mobile for up to a minute or two, then cure within seconds. Because they weight as little as 1/50th the weight of traditional cementitious grouts, they are much less likely to cause further settlement from their own weight.
Settlement Correction
Some CJGrout geotechnical polyurethanes are designed for low mobility grouting. They stop flowing before they stop expanding, which allows them to compress loose soils, and to lift settled pavement and structures.
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 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.
Soil Strengthening
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 Injection Grouting Materials
There are many types of chemical grouts used in injection grouting. 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.
Acrylic Grouts
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.
Speak With An Expert
Facing a challenge? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
