GEC understands that choosing the correct type of grout and designing the grout to meet the project requirements is imperative to a successful project (there’s never been a successful grouting project where no grout was pumped into the ground!). There are numerous factors that go into grout type selection, these include project conditions, project requirements, project access, and most important in many applications, project geology.
GEC is unique in that we are a small company that has the experience and capabilities to utilize virtually all types of grouting and grout materials. We commonly utilize cement grouts (Portland Cement, Microfine Cement, and Ultrafine Cement), chemical grouts (polyurethanes, sodium silicates, and acrylamides/acrylates), as well as epoxy resins and bituminous grouts at times. Unlike many companies who only utilize a certain type of grout and try to make their grout fit the project, GEC can evaluate the project and recommend the grout type which will be the best value to the job, based on both the performance requirements and economics.
Cement based grouts are most commonly used by GEC. In most of our grouting applications, these grouts offer the most appropriate properties for the job and in general are the least expensive grout material. Cementitious grouts can be applicable for any type of grouting service, as long as the aperture being grouting is large enough to accept the cement particles.
GEC has a track record of completing jobs successfully with neat cement grouts with the use of dispersants. Although these grouts are appropriate for many jobs, we also have the ability to design cementitious grouts with enhanced properties when the conditions necessitate. Common grout properties that may be adjusted include:
- Pressure Filtration
- Thixotropic Set
- Initial and Final Set
- Compressive Strength
These properties may need to be controlled to improve grout for reasons such as pumpability, penetration, anti-washout characteristics, grout mobility, etc. Through the use of additives, all of these grout properties can be adjusted. GEC has designed cementitious grouts for pumping in lines as small as quarter inch diameter, for distances as long as two miles, for underwater placement in open fractures, and for gaining control of water discharges up to 1,800 gpm. Additionally, GEC has designed and utilized Balanced Stabilized Grouts (BSG) which are completely compliant with some of the most rigorous specifications in the industry.
Many people use the term “Chemical Grouting” to refer to any grouting technique that is performed with chemical grouts. However, this can be confusing due to the large number of chemical grouts available and the numerous grouting techniques for which they can be utilized. Generally, chemical grouts may be applicable for any type of grouting technique (structural, permeation, consolidation). The decision to use a chemical grout should be based on the advantages of the chemical grout over cementitious grouts, as the material cost is generally higher. Common types of chemical grouts and typical applications follow:
There are a large number of polyurethane grouts on the market, each of which has specific properties which have been designed to address various situations associated with their intended use. However, polyurethane’s greatest advantage is a short set time (on the order of seconds). This, along with other characteristics, often makes it the preferred choice when performing water cutoff grouting. It is often used to seal off rock faces, concrete, or other leaking structures. Additionally, polyurethane is used in permeation grouting to provide bearing capacity improvements, in structural applications, or to fill large voids (due to some formulations expansive characteristics).
Sodium silicate grouts are generally the preferred choice for permeation grouting. This is because they are a solution grout, have a relatively low viscosity, have a controllable set time, and are less expensive than most chemical grouts. Also, these grouts are sometimes used for consolidation grouting when particulate grouts will not penetrate very small rock mass discontinuities.
Acrylamides and Acrylates are similar in formulation. Acrylamides offer a slightly lower viscosity and a longer lifespan while Acrylates may be somewhat easier to handle on site. Due to their extremely low viscosity (almost equivalent to water), these grouts are generally used when other grout types will not penetrate the void space that is trying to be filled. They are most often used in permeation grouting for reduction of hydraulic conductivity. However, they may also be used in consolidation grouting when microfractures are present or when the highest degree of water cutoff is required.
Epoxy resins are almost exclusively used for structural grouting. The advantages offered are high strength and bonding capabilities. In grouting applications, epoxy resins are most often used to repair cracks in concrete or to fill other small spaces in structures where strength is required.
Bituminous grouting is also known as asphalt grouting. This grouting technique involves the injection of an asphalt material (similar to roofing tar). The method is almost exclusively used for stopping large inflows (generally greater than 1,000 gpm), although may be used in applications where its elasticity in the cured state is desirable. Bituminous grouting is generally used where void size or water flow is too great to allow other grouting methods to work due to grout washout. The advantage of bituminous grout is that as the hot bitumen is pumped into the ground, eventually, a leading edge of cured, elastic bitumen forms. Additionally grout fills the cured leading edge and expands the grout mass, similar to inflating a balloon. The leading edge forms a protective layer, keeping additional grout from being washed out. Eventually, the mass will grow large enough to either fill the void space available at the injection point, creating a seal within the void.
Bituminous grouting applications are most often associated with mining operations such as quarries or with dams which are experiencing large volumes of seepage. GEC has the capability to design and place bituminous grouts based on the project requirements.