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30 June 2020

Injection Grout Crack Injection 101

Posted in Industry News

This blog topic dives deeper into industrial grouting in concrete structures such as basement walls, parking garages, storage tanks and more.

Necessary Equipment - There is a belief that every grouting project has the need for large, very expensive equipment. While there are projects that require specific machinery and equipment  that may be quite the investment, other projects can be grouted successfully using an airless paint sprayer such as the Graco Ultramax II 495 PC PRO, a few clean buckets and standard tools you can find in almost any tool box. Below is a list of common materials and equipment to have at your next grouting
project (please note these are suggestions and not a complete list):

  • Proper PPE - gloves safety glasses, eyewash station, etc. 
  • Tripod + Safety Harness
  • Gas Monitor
  • Pumps and Hoses - Resin and Water pump
  • Drill + Drill Bits
  • Grout + Catalyst (if catalyst is necessary)
  • Auxiliary Products such as AV-219 Oakum
  • Injectors/Packers
  • Clean 5-gallon buckets
  • Misc. Tools and Accessories - flashlights, thick-mil garbage bags, etc.

Slow vs. Fast Water Leaks in Below-Grade Structures - Slow water leaks can often be addressed using the Variable Pressure Application Technique (VPAT) Method. When using the VPAT Method, the grout selected should be based on the environment surrounding the structure as well as the width of the crack. In areas of high humidity, a hydrophilic grout is suggested as product of choice. If the structure is in an arid climate or has wet/dry cycles, consider using a flexible hydrophobic grout. Fast water leaks are often a sign of significant void space in the soils outside the structure and often require a different approach than that used for slow leaks. When addressing high flow areas, consider damming the crack with dry, oil free Oakum - saturated with a hydrophilic grout to slow the water down, then use a hydrophobic grout to fill the void space in the soil surrounding the structure.

Small vs. Large Cracks in Concrete - Viscosity Matters - When selecting a product for crack sealing, you must determine which material will flow through the crack the best - we refer to this as viscosity which is measured by centipoise (cP). For an approximate reference, water is 1 cP and honey is 3,000 cP. There are many product choices for various types of cracks in concrete structures, however below is a quick reference guide to help determine what product may be most  appropriate for your project -  our technical sales team is available to answer your questions and point you in the correct product direction.

Crack Type Product  Centipoise (cP)
Hairline cracks AV-150 Acrylate Gel
AV-315 Microfoam
15-20 cP
50-75 cP
<.50" AV-202-LV Multigrout LV
AV-248-LV Flexseal LV
650-800 cP
550-830 cP
>.50" AV-202 Multigrout 3,200-6,200 cP

Drill Hole (Ports): Spacing
- Drill hole (port) spacing is an important step to the injection grouting process. When crack injecting, a good rule of thumb is drilling port holes at a 45-degree angle, half the wall thickness off the crack. For example, if the wall is 12" thick, the ports should be drilled 6" away from the crack. The best way to determine the distance between ports is to monitor the water flow. The termination point of water travel is the best location for the next port. As the crack gets wider, the space between holes can increase. Ports should always be staggered from one side of the crack to the opposite side, making a zigzag or stitch pattern. Using injection ports on alternating sides of the crack helps to prevent spalling and helps ensure interception of the crack. This is a recommended guideline based on experience. Each job is unique and could require deviation from this guideline depending on job site conditions