Soil stabilization that fixes the base where it lies

A road fails from underneath long before it looks like it is failing. Stabilization treats the soil already on site so it carries the load, rather than trucking it away and buying replacement material to put in the same place.

Request a Project Assessment Call 936-208-9076
A motor grader working a wide unpaved road base on an industrial site, with cranes along the shoreline behind
Road base work on an industrial site. From the product line's project record.

Why road bases fail

You usually pay for the subgrade twice: once when the surface fails early because the layer underneath could not carry the load, and again when the fix is a full reconstruction.

  • Hauling dominates the estimate

    Trucking in base material and hauling the old material off is often the largest single line in a reconstruction, before any of it is placed.

  • Water gets in and stays in

    A permeable base holds water against the structure. Saturation and heavy axles turn that into rutting and potholes on a predictable schedule.

  • Cement buys strength and loses flexibility

    Raising cement content raises compressive strength, but the layer gets more brittle as it gets stronger, which is why many transportation departments cap the percentage allowed.

What stabilization changes

Top-Seal White is worked into the existing base and compacted. As it dries it binds the soil into a single treated layer. Two properties do most of the work.

Load bearing capacity

Independent testing of treated and untreated samples recorded a large increase in unconfined compressive strength. A base that carries more load passes less stress to everything above it.

Resistance to water

The same testing recorded a lower permeability coefficient for treated soil. Water that cannot get into the structure cannot do the damage that follows saturation.

Strength without the brittleness

A University of Texas at Austin study of polymer sealants in soil-cement base stabilization reported that polymer stabilized bases provide the slab-like characteristics of soil-cement while adding flexibility, and concluded that shear stress resistance is not sacrificed for high compressive strength.

Source: Improving Soil-Cement Base Stabilization with Polymer Sealants, Drit Sokoli, University of Texas at Austin, October 2014. Download the study (PDF)

A smooth, sealed section of road base beside a strip of loose, untreated material
A finished, sealed section beside loose material still to be worked. From the product line's project record.

The documented process

This is the sequence in the published stabilization application specification. A crew that has built a road has run every one of these machines before.

How a road base is stabilized, in four steps A section through a road. A grader scarifies the existing base to about six inches. A water truck sprays diluted product into the loosened soil, shown in orange. A roller mixes and compacts the treated layer. A final overcoat seals the surface, which dries by evaporation. Native soil Compacted subgrade about 6 in Existing base Scarified base Product applied Treated and compacted base Overcoat
Illustration of the sequence in the published stabilization application specification. Rates, equipment, and depth are set for each site.

  1. A motor grader rips the existing road to a depth of about six inches, opening the base so the product can reach through it.

  2. The product is diluted in a water truck and sprayed onto the loosened soil through a spray bar.

  3. The grader works the treated soil back to line and grade, mixing the product through it, and rollers compact it to density.

  4. A final overcoat seals the surface, which dries by evaporation, overnight in dry, warm conditions, before traffic.

Equipment by finish level

  • Basic finish

    • Motor grader with blade and ripper
    • Water truck
    • Rubber wheel compactor

  • Standard finish

    • Motor grader with blade and ripper
    • Water truck
    • Rubber wheel compactor
    • Steel drum compactor

  • Premium finish

    • Motor grader with blade and ripper
    • Cold recycler and soil stabilizer
    • Sheepsfoot compactor
    • Steel drum compactor
    • Water truck

Source: the published stabilization application specification. Application rates depend on soil quality, lift depth, and loading, so we work them out for each site rather than publishing one figure.

The data an engineer asks for first

Holt Engineering tested soil untreated and treated with Top-Seal White. These are results from specific tests on specific samples. Performance on your project depends on your soil, the application, and the installation.

Unconfined compressive strength (PSI)
Sample PSI
Untreated soil 132
Top-Seal White, medium strength 1,400
Top-Seal White, high strength 2,200
Source: Holt Engineering compressive strength testing, as reported in the product line's engineering presentation.
Permeability coefficient
Sample Coefficient
EPA reference standard 1.00E-07
Top-Seal White, medium strength 3.20E-08
Top-Seal White, high strength 1.00E-09
A lower coefficient means the soil lets less water through. The EPA reference standard is shown for comparison. Source: Holt Engineering permeability testing, Austin, Texas, January 8 2018, as reported in the landfill composite liner drawing.

Where it applies

The specification covers construction or reconstruction of a soil base for these, and for other projects that need more traffic bearing capacity.

  • Roadways

    New construction and reconstruction of the soil base.

  • Airfields

    Runways, taxiways, and aprons.

  • Parking lots

    Commercial, industrial, and public parking.

  • Pads and yards

    Building and commercial pads, and areas that carry heavy equipment.

A finished, smooth unpaved private road edged with limestone rock, branching through oak and cedar trees
A finished stabilized private road. From the product line's project record.

Landfill covers, liners, and slopes

The same product is used on landfill soils. The published composite liner and cover drawing identifies two uses.

  • Improving soil that misses its coefficient

    Treating compacted soil that does not currently meet permeability coefficient standards.

  • Alongside or instead of a membrane liner

    As an alternative or complement to flexible membrane liners on soil that already meets the standard. The drawing conditions this on an EPA waiver, and that condition travels with it.

In both cases the drawing places the product in the upper six to twelve inches of compacted soil, above the drainage layer and beneath the protective soil layer. It is also used on slopes, embankments, and retention areas where soil moves.

The landfill procedure

Water goes into the truck before the product. The first pass goes on by water truck on flat ground and gentle inclines, or by a broadcasting hose on steeper slopes, and is compacted once it has soaked in. The procedure describes waiting at least 24 hours before a second pass as beneficial. The second pass seals the surface and needs no further compaction.

Dilution for this procedure only: 1 part product to 5 parts water. Source: Landfill application procedures. Rates for other applications are different and are not interchangeable.

A water retention pond with banks of compacted red soil and young palms planted along the edge
Stabilized soil around a water retention pond. From the product line's project record.

Maintenance a small crew can handle

Pothole patching. Mix extra road base with product in a wheelbarrow or bucket, fill the hole, finish it to grade, let it dry, then overcoat three feet out in every direction. A garden sprayer is enough for the overcoat.

Maintenance application. A repeat of the final overcoat, applied by water truck at the same concentration as the original.

Source: the published stabilization application specification.

What we are not claiming

  • We do not publish a road lifespan or a maintenance interval. Neither has been established for your soil and traffic.
  • The test values above are results on specific samples, not a guaranteed property of the product on your site.
  • It does not replace a designed landfill liner system, and any substitution for a membrane needs the EPA waiver the source document names.
  • We make no claim that it prevents methane or all liquids and gases from escaping, or guarantees permeability compliance. Compliance depends on your soil, your application, and your regulator.

Products and documents

Top-Seal White is the stabilizer. Top-Seal Black goes over a stabilized base where a road needs a wearing surface.

For haul roads where dust is the daily problem, see dust control.

Send us a road and we will tell you what it needs

Location, length, width, the current surface, the soil if you know it, and what drives across it. You get back an assessment of fit and what an application on that site would involve.

Request a Project Assessment

936-208-9076
info@solidearthsolutions.com

We reply within 24 to 48 hours.