In this post, I’m going to personally review two popular methods used to handle water leaks and infiltration. Both hydraulic cement and chemical polyurethane grouts are used in civil applications such as sewer pipe rehabilitation, tunnel or shaft construction, sealing leaking cracks in concrete structures, permeating soil to control the flow of groundwater, filling voids to stabilize soil, and handling common inflow and infiltration issues found all over the world.

This post will reveal the good, the bad, (and the ugly) when it comes to product selection and application. When considering chemical grout or hydraulic cement for your waterproofing needs, we will need to look at:

• Features
• Costs
• Applications

When it comes to waterproofing with chemical grouts, application techniques will make or break a job. There is a lot of misinformation out there, so I encourage you to carefully evaluate the content below and make the most educated decision for your upcoming projects. (For further assistance with that decision, feel free to call our tech support team at 404-618-0438.)

Before we continue, I’d like to briefly let you know who I am and what I do. My name is Charlie Lerman (a.k.a. The Grout Geek). I was the Technical Field Services Manager at two industry-leading polyurethane grout manufacturers for 18+ years before joining Alchemy-Spetec as the Director of Technical Services – Leak Seal Division. My full-time responsibility is to take care of your questions and uncertainties concerning waterproofing with chemical grout and alternative options. So when is it best to use hydraulic cement? When should you use chemical grout? Let’s compare:

What is Hydraulic Cement? Key Features

Hydraulic cement is inexpensive and easy to apply but its benefits stop there. It is a surface patch that is primarily applied to the negative side. It has a weak adhesion and thus is applied in a groove or similar cut. It can be used to shut down low-pressure leaks. Being that it is cement it has a low tensile strength which means just like other types of cement it will be brittle when it is cured.

Chemical Grout Features

There are two primary types of chemical grouts when it comes to crack injection, each unique in its composition and makeup: (1) acrylics and (2) polyurethanes.

1. Acrylic grouts are free of suspended solids and have extremely low viscosity. The grouts can change from a liquid to a solid in a controllable gel time ranging from 3 seconds up to 10 plus hours. The lifespan of acrylic grouts is estimated to be between 50-300 years depending on the method and application utilized. Acrylic grouts are hydrophilic, have about 500% elongation, and are only about 20 cps. These properties make them ideal for injecting hairline cracks. Alchemy-Spetec's Spetec AG200 acrylic injection resin is NSF 61-5 certified for contact with drinking water.

2. Polyurethane grouts can be grouped into two types: hydrophilic and hydrophobic. Hydrophilic grouts are usually single component formulations that react with water and cure to an expansive flexible foam or non-expansive gel requiring a moist/humid environment after curing. Hydrophobic grouts are expansive foams that require little water to react and can easily withstand wet/dry cycles. Hydrophilic foams expand 4 to 6 times their original volume, while hydrophobic foams can expand up to 40 times their original volume and may cure flexibly or rigidly. Alchemy-Spetec offers many polyurethane resins that are NSF 61-5 certified for contact with drinking water. The lifespan of polyurethane foam is estimated to be approximately 70+ years.

Both acrylic and polyurethane chemical grouts are injected into cracks or joints and thus are not considered a negative side waterproofing even though they are often applied from the negative side. Acrylic and flexible polyurethanes are designed to shut down active leaks and, because of their high tensile strengths, they can withstand the movement of a dynamic crack or joint. Because they are full-depth repair materials, they can also encapsulate rebar and thus help prevent corrosion, spalling, and thus structural failure.

Applications: When, Where, and Why

I cannot emphasize enough how helpful it is to speak with an experienced grout consultant and/or an experienced contractor when faced with the need to stop leaks or control inflow and infiltration. If you are looking for installation recommendations, a knowledgeable grout manufacturer should be consulted to assist with proper grout selection and installation methodology. I am available to assist with your next project. Call Alchemy-Spetec at 404-618-0438 and ask for the Grout Geek!

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