Good Chemistry

Competitors agree that installers hold the key to successful chemical grout applications for the
wastewater collection system.

Avanti International and W. R Grace & Co. (parent company of De Neef Construction Chemicals Inc.) are competitors in the manufacture of chemical grout and don’t always share the same point of view. But there is one thing we agree on: In order for the industry to continue growing, we need to come together to shed light on the benefits of chemical grout as a viable option for infiltration control and — most importantly — make sure that each and every application is successful. 

Our companies offer many product options for the wastewater collection system and, when asked, we often make product recommendations. But in order for a grout application to be successful, these products must be specified correctly and the most critical players in the selection of grout are the installers. They hold the key to providing information regarding the working environment and other, oftentimes unforeseen site conditions that will ensure the most appropriate chemical grout product is selected; they must be part of this selection process.

When selecting chemical grouting, there are many choices which, typically, fall into the acrylic family (acrylamide, acrylic and acrylate grouts) or the urethane/polyurethane family, which is made up of foams or gels. Given the length limitations of this article, the focus will be on polyurethanes, which are separated into two major categories, each with their own unique benefits, considerations and uses:

Hydrophilic: Simply described, these are water-friendly grouts. Because hydrophilics are water-friendly, they need to be applied in a moist environment or they will experience a shrinkage factor. These resin-only materials are at the mercy of groundwater temperatures for the set time. Therefore, an installer needs to take into account, when selecting a hydrophilic, that in colder water these grouts will have a longer set time. However, a major benefit of hydrophilic grout is a high bond strength. This capability is based on the ability of the grout material to reach out into capillaries, extract water residing in concrete, and thereby create additional strength.

Hydrophobic: As the word “phobia” implies, these grouts are less dependent on water during and after curing. They tolerate wet/dry cycles well and have the ability to add a catalyst, which offers the potential for higher volume expansion and faster set times. The bond strength of Hydrophobics will be lower than that of a hydrophilic grout. Since sewer collection system applications are not typically affected by major temperature changes, in most cases thermal movement would not be a major concern.

When selecting the most appropriate grout material for an application, there are several considerations that must be taken into account, including the following:

• In addition to deciding between hydrophilic and hydrophobic grout, a determination should be made whether the end product needs to be rigid or flexible. If a crack in a structure is caused by movement, the crack should be filled with a flexible product that can move along with the structure.
• When selecting a product for an area that has a deep freeze zone, a high water content grout should not be selected, because the upper portion of the manhole may be exposed to freezing and thawing.
• When selecting a product for a condition with extreme wet/dry cycling, or where water rises and then recedes (such as snow run-off), higher water content grouts may experience shrinkage during those times when water or moisture is not present.

Common Goal
Our mutually common goal is to make sure each and every chemical grout application is a success. As Avanti International and W.R. Grace & Co. come together to educate the industry, we encourage   installers to be actively involved in the final decision regarding which type of chemical grout solution will work best for each specific application.

We also stand side-by-side as members of the Infiltration Control Grouting Association (ICGA), a division of NASSCO. Through this association, we work together and with others in our industry to establish and set industry standards for the assessment and rehabilitation of underground sewer infrastructure and to assure the continued quality, acceptance and growth of trenchless technologies, such as the use of chemical grout.
ICGA is a great resource for installers and anyone involved in infiltration control to gain knowledge and work with peers to ensure quality applications. Visit sewergrouting.com to learn more about membership, download specifications such as the “Suggested Standard Specification for Pressure Testing and Grouting of Sewer Pipe Joints, Laterals and Lateral Connections Using the Packer Method with Solution Grouts,” or view the recent Water Environment Federation (WEF) Webcast, sponsored by ICGA, titled “Chemical Grouting: Control Infiltration and Sustain  Existing Sewer Collection Systems Assets.” 

For more information about Avanti International’s commitment to education and helping its customers grow their business, visit avantigrout.com. To learn more about innovations from W.R. Grace & Co., such as new potable water-approved mainline grouts, please visit deneef.com.

Daniel Magill is president of Avanti International. Ed Paradis is sales manager and director of municipal operations for W.R. Grace & Co.