Polyurethane is the process of injecting expanding polyurethane grout into voided areas, inside structures or under slabs-on-grade in order to fill voids or relevel slabs. Polyurethane grouting is a fast, efficient repair process for improving settled and unstable concrete. From sidewalks to interstates, and everything in between.

How Polyurethane Grouting Works in Alameda County

Two polyurethane liquid components are mixed and injected (also known as polyurethane injection) under pressure below the area or structure being repaired. The two liquids respond with each other, expand and harden, like the foam you get in a can to seal around windows. At Geo Grout Ground Modification Specialists Inc., our polyurethane grouts stay a liquid for a few seconds before expanding. This helps them spread out from the exact spot they’re injected, but then get harder much faster, and can exert much more force during expansion. The grouts we use (TerraThane) are specially formed to be very strong and long-lasting in contact with the ground.

Common uses of Polyurethane Grouting

  • Create barriers to water flow
  • Fill Voids
  • Re-level slabs
  • Seal crack and joints

What polyurethane grouting Is Best For You?

There are several times when polyurethane grouting is the only restoration process that will address a problem. Here are some of the times when polyurethane grouting is essential:

Large slabs

Large slabs (typically larger than 100 square feet) are best fixed with polyurethane grouting because polyurethane can travel under the entire slab from just one or two injection holes. This creates a more diffuse lifting force than grout. This speeds up work and reduces the chance of breaking.
Faster reacting lower density foams typically begin to expand within a few seconds of injection, so they are good for concentrated lifting. Slower reacting, higher density foams can travel as a liquid for up to 45 seconds before starting to expand and harden. This allows them to lift extremely large areas, as the liquid is injected at 1100 psi, which forces it into what can be very small spaces under the slab.

Heavy slabs

Because of its high development force and ability to spread under large areas of slabs and structures before expanding, high-density polyurethane can lift extremely heavy slabs with ease. These involve roadway slabs, bridge approaches, rail crossings and slabs with heavy loads, such as machinery bases and floors with backup battery power packs.

Areas where cleanliness is important

Due to the small, infrequent holes, dustless drilling is easy. Additionally, because there is a mechanical connection between the injection equipment and the slab, no material is exposed to the surface or surroundings. Automated, mechanical devices on the injection equipment prevent leakage of material when not injecting. We use special dustless drilling equipment for most interior jobs.

Sensitive or expensive surfaces

Polyurethane grouting accepts small (dime-size) holes that can be stored infrequently. It is a perfect repair method for settled slabs which have decorative coatings, surface treatments or other characteristics, such as brick and stone overlays. Injection holes can be patched with stained concrete to blend in with floor coverings. For repairing slab floors with wood, we use a 1″ whole saw to cut a small access area to the floor, which can then be puttied back into place after lifting is completed. For carpeted areas, three sides of 2″ squares can be cut to reveal floor and then be glued back down after injection.

Load-sensitive areas

The usual cause of slab settlement is inadequate compaction or bearing capacity of the underlying soils. Because high-density polyurethane is lightweight (typically 2.5 to 6 pounds per cubic foot), there is very small added weight transferred to the underlying soil as part of repairs. This helps to minimize the chances of resettlement. Sand-based and cementitious grouts applied for slab jacking or pressure grouting typically weigh more than 100 pounds per cubic foot. The weight savings with polyurethane grouting are significant.

Isolated sites

Because high-density polyurethane is stored and transported as a liquid which then expands. A single non-CDL box truck can easily carry more than 80 cubic yards of expanded material. The equivalent for slab jacking grout would need more than 6 large dump truck loads and onsite handling equipment. Raw polyurethane material is carried in standard chemical totes. So is easily transported, stored and handled on job sites.

Talk to Us

Have questions about an application for polyurethane grouting Alameda County?  Email us at inquiries@gggms.com, or call (650) 241-2400 for more detailed information on our services.

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