Testing for Suitability for Treatment with TERRA-3000

Testing is beneficial in determining the suitability of candidate materials to be treated with TERRA-3000.

Successful stabilisation with TERRA-3000 relies on appropriate candidate materials, even application of TERRA-3000, thorough mixing and sustained static compaction (we refer to this as dwell time).

Foremost, candidate materials must contain adequate fines (silt and clay).

Critical Test Result Data:

TestResult DataCommentaryRecommendation
Particle Distribution AnalysisRock Fraction (%)
Fraction not passing 37.5 mm sieve.
Fraction not suitable for treatment with TERRA-3000.Crush fraction using vibrating roller.
Particle Distribution AnalysisGravel Fraction (%)
Range 2.36-37.5 mm
Recommended Fraction 1/3.Adjust fraction as required.
Particle Distribution AnalysisSand Fraction (%)
Range 0.075-2.000 mm
Recommended Fraction 1/3.Adjust fraction as required.
Particle Distribution AnalysisSilt & Clay Fraction (%) [Fines]
Fraction passing 0.075 mm sieve.

Recommended Fraction 1/3.Treatment with TERRA-3000 requires the presence of silt and clay fines.Adjust fraction as required.
Hydrometer Analysis Note 1Silt Fraction (%)Refer notes under heading Clay below. 
Hydrometer Analysis Note 1Clay Fraction (%)Recommended Minimum 15%Refer notes under heading Clay below. 
Proctor TestNatural Moisture Content (%)NMC assists in determining the dilution rate of TERRA-3000 Concentrate prior to treatment. 
Proctor TestOptimum Moisture Content (%)OMC assists in determining the dilution rate of TERRA-3000 Concentrate prior to treatment. 

Note 1: laser diffraction particle size analysis is faster, more accurate and less expensive for regular testing than traditional hydrometer tests. There are a number of in-situ and lab based units available such as the LA-960 Laser Particle Size Analyzer manufactured by Horiba (Reference: https://www.horiba.com/scientific/products/particle-characterization/particle-size-analysis/details/la-960-laser-particle-size-analyzer-20235/).

Required during planning.

Required during treatment.

Candidate Materials


For optimal results, the candidate material should contain no fraction > than 37.5 mm, contain a  minimum clay fraction of 15% and minimum combined clay/silt fraction of 20% and a maximum clay fraction of 30% and maximum combined clay/silt fraction of 40%. Candidate materials can be improved with the addition of gravel, sand, clay and silt where deficient.

Optimal Particle Distribution (⅓ Rule):

⅓ FINES (<0.75 mm)

⅓ SANDS (RANGE 0.075-2.000 mm)

⅓ GRAVELS (RANGE 2.36-37.5 mm)

0 STONE (>37.5 mm) Crush STONE fraction using vibration prior to treatment.

Particle Distribution Analyses may be compared to our Model Particle Distribution* tool to determine whether the candidate material would benefit from the addition of gravel, sand, silt or clay prior to treatment.

 *Please contact support@terrasystem.com.au to gain access to the Model Particle Distribution tool.

In-Situ Modulus

Modulus is the most accurate and independent means for judging deformation (stiffness) and therefore, a materials level of compaction. Modern geotechnical and pavement designs are based on in-situ modulus values.

We recommend in-situ modulus testing using a Light Weight Deflectometer before, during and upon completion of stabilisation with TERRA-3000.

Water Absorption Test

Water penetration undermines the stability of pavements.

One of the primary advantages of stabilisation with TERRA-3000 over other methods is the loss in capillary action of the treated layer following treatment.

This loss of capillary action assists to prevent damage from ground waters or inundation during rain events.

The extent to which stabilisation with TERRA-3000 prevent the ingress of water following treatment can be assessed applying the TERRA-3000 Water Absorption Test Procedure.

In essence, both treated and untreated materials are separately placed in a perforated tube affixed to a hydraulic jack then compacted at equal pressure and dwell time producing compacted cores (called pucks).

Sample weights are observed before and after compaction and after soaking over a number of days to determine the rate of absorption.Observation of capillary rise in untreated samples is often rapid and leads to a complete failure of untreated pucks. In comparison, often after establishing test results, we have chosen to leave treated pucks immersed in water indefinitely to demonstrate the long term benefits of treatment to our clients. For more information on the TERRA-3000 Water Absorption Test Procedure visit.