US Grout Logo

Seal Fractures in Rock and Concrete Structures

Microfractures as small as 6 microns are successfully penetrated and sealed by US Grout Ultrafine. Our grout can effectively control water infiltration in tunnels, shafts and mines, repair concrete structures, seal and prevent exfiltration in underground confinement chambers, and squeeze-cement oil and gas wells.

Standard cementitious grouts (suspended-particle grouts) contain unacceptably large particle diameters—too large to effectively enter and seal microfractures in rock and concrete structures.

size matters: ultrafine particles are crucial to successfully grout microfractures in rock and concrete structures

Size Matters

When it comes to successfully penetrating and closing microfractures with suspended-particle cementitious grouts, size matters.

Successfully sealing and reducing the transmissivity of a rock mass with a cementitious suspended-particle grout requires a carefully-tuned rheology (fluidity) centered around a maximum particle dimension that does not exceed one-third to one-half of the fracture aperture—the solid particles must be fine enough to stay suspended in the liquid even when squeezed into microfissures.

On-job verification testing by Sandia National Laboratories showed US Grout Ultrafine to have successfully penetrated microfractures as small as 6µm consistently to depths of up to 3 meters. The microscopic examination of grouted rock samples also revealed that the grout was homogeneous and stable (did not separate into liquid and solid phases) and completely conformed to fracture morphology.

And unlike chemical grouts (also known as solution grouts), ultrafine cementitious grouts do not present environmental, worker safety or high-cost concerns.

Pozzolan-Charged Cementitious Grout

Unique among the cementitious grouts available today, US Grout’s products are designed with a pozzolanic charge—a benefit-inducing secondary reaction within the hydrated cement paste that effectively improves the strength, performance characteristics and life-span of the cured grout.

An explanation of what takes place during this pozzolanic reaction and how it cleans up the problems that affect ordinary standard cementitious grouts is detailed on this page: Pozzolanic Charge Defined.

A Superior Grout

Ask an engineer to detail the characteristics of a superior fracture-sealing grout, and you would probably hear the following: wide range of water-to-cement ratios, little or no bleed, generous injectability window, adjustable rheology and set time, extremely low hydraulic conductivity, volume stability, negligible contraction cracking from heat of hydration, impressive strength, and resistance to chemical attack.

Many would also list ease-of-use expectations like a ready-to-mix-and-pump product, the availability of custom blends, a stable, competitively-priced supply, stringent quality control to insure uniformity and beginning-to-end predictability, expert technical support, an international distribution network, and a safe-to-use, non-hazardous product. US Grout Ultrafine grouts deliver all of the above.

The story behind the development of our high-performance grout details the circumstances that launched the R&D to create a new cementitious grout when it was determined that none of the grout products commercially available could meet the U.S. Department of Energy’s project-critical need.

That grout technology was subsequently licensed to US Grout to be manufactured and distributed world-wide.


Cementitious grouts are used for a wide variety of civil-scale construction and repair projects to meet the demands of cost, longevity, strength, performance, and ease of use.

cutting out a storage cavern in saltrock, deep underground
  • Waste Containment Vaults—Whether naturally occurring or as the result of closure forces from the relentless weight above, cracks in the walls of waste containment vaults need to be completely and permanently filled.
    (EXAMPLE: U.S. Department of Energy's WIPP site)
  • Underground Liquid Storage Vaults—What is pumped into such vaults—petroleum or otherwise—needs to stay there, untouched by infiltrates.
  • Aprons Beside and Beneath Concrete Dams—The integrity of concrete dam is only as good as the surrounding and supporting rock into which it was built.
  • Concrete Infrastructure—It's just good chemistry: using cementitious grout to seal cracks in concrete structures such as dams, bridges, seawalls, retaining walls, support structures.
  • Tunnels—Whether using grout-and blast construction methods or adding a water-denying grout curtain behind the walls of a bore, the nirvana of tunnel engineering is “tight and dry.”
    (EXAMPLE: Intake Tunnel #2 Beneath Lake Mead)
  • Roadway Cuts—Keep the water out of the rock cracks and the relentless freeze-thaw cycle is short-circuited.
  • Some of the rehabilitate-and-repair uses for a deep-penetrating, microfracture-sealing, high-performance, easy-to-use cementitious grout:
  • Groundwater Inflow in Mines, Tunnels and Vertical Shafts
  • Retaining Walls
  • Bridge Abutments
  • Concrete Pylons and Footings
  • Canal Linings and Control Gates
  • Concrete Seawall and Levees
  • Water Treatment Facilities—Concrete pond linings, tanks and oxidation ditches.
  • Parking Structures
  • Masonry Block Walls and Foundations
  • In-Ground Storage Vaults, Ponds and Silos
  • Containment Domes
  • In the cases of concrete-meets-soil structures, the soil behind and beneath over-stressed concrete structures can be stabilized and solidified by the direct injection of cementitious grout. [ MORE on SOIL STABILIZATION]
US Grout products use conventional mixing and placing equipment

Conventional Grouting Practices, Unconventional Grout

Rest easy. US Grout products were formulated for tough grouting situations, but designed to be placed by conventional grout practices and equipment. Our grouts offer a generous two-plus hour injectability window, are simple to properly mix, and are safe to use.

US Grout products are sourced and made in America, are available via an international distribution network, and backed by many years of practical grouting experience.

Expert Support

As the world-wide distributor for US Grout products, Avanti International ( • 800-877-2570) provides the customer service, objective professional advice, material estimates, and the caliber of world-class technical support that comes only from 35 years of geotechnical experience.

US Grout Ultrafine Particle Size Information

Particle size and internal cohesion, not viscosity, determine a grout's ability to penetrate extremely small openings. 90% of the particles in Ultrafine grout are smaller than 8 microns and average 3 microns.

micrograph of ultrafine particle grout passing through an 8 micron constriction

PHOTO: A backscattered microphoto showing US Grout Ultrafine passing through a 7.9µ constriction.

Absorbing Heavy Metals

As in all Portland Cements, our cementitious grouts have a tendency to absorb and immobilize heavy metals such as plutonium, actinium, strontium, uranium, etc. This is especially advantageous if the task for the grout is locking down waste.

822 Bay Star Blvd., Webster, TX 77598


Contact Avanti International:
1 (800) 877.2570
1 (281) 486.5600