phone icon

1300 166 166

Quote-icon

Get a quote

Compaction Matrix

Your Comprehensive Guide to Compaction Methods

In civil, road, and infrastructure projects around Australia and beyond, achieving optimal ground stability is foundational to long-term success.

The right compaction method ensures durability, prevents costly settlement, and provides a solid base for any structure or surface.

With a diverse range of techniques available, from powerful impact rollers to precision light tools, understanding their unique applications, strengths, and limitations is key to making informed project decisions.

A bright yellow industrial vehicle operates on a rugged, dusty site with rocky cliffs in the background, pulling a large Compaction Matrix attachment designed for ground leveling or excavation.

Rolling Dynamic Compaction / High Energy Impact Compaction - (RDC / HEIC)

A stylized yellow abstract shape with a circular, gear-like Compaction Matrix center sits above a thin horizontal line, with curved lines below resembling sound waves or a signal. The background is white.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Ground Improvement: Enhancing bearing capacity and reducing settlement for foundations, pavements, and various structures.
  • Infrastructure Support: Stabilising ground for roads, railways, airport runways, parking areas, and bridge approaches.
  • Liquefaction Mitigation: Reducing the risk of liquefaction in seismic zones.
  • Site Remediation: Stabilizing waste, old landfills, and compacting contaminated or deleterious materials.
  • Mining Sector: Improving stability of mine haul roads and compacting tailings dams.

  • Agricultural sector: Compaction of water storage base and side wall to reduce water seepage loss. Compaction of irrigation water channel banks.

  • Cost & Time Efficiency: Offering an alternative to over-excavation and replacement.
Depth of significant improvement 2 – 4+ meters (8 – 13+ ft).
  • Granular Fills: A wide range, including uncontrolled fills, brownfield sites, dredged sands, and materials used for mine haul roads and tip heads.
  • Mixed Soils: Select mixed granular and cohesive fills.
  • Waste Materials: Waste fills and old landfill materials (Landfill capping layer.).
  • Problematic Materials: Contaminated or deleterious materials (e.g., Acid Sulphate Soils, asbestos).
  • Achieves significant depths of densification efficiently, increasing the strength and stiffness of the impacted materials.
  • Offers very high productivity over large, open areas due to its continuous rolling motion.

  • Can be effective in unsaturated cohesive soils, with moisture contents below optimum.

  • Can be a cost-effective solution for improving ground at shallow to medium depths.
  • Effective across a wide range of granular materials, various soil types and highly variable or uncontrolled fills.
  • Significantly enhances the soil’s bearing capacity and reduces its liquefaction potential.
  • Generates high ground vibrations, which can be a concern near sensitive structures or populated areas.
  • The process can leave a rough and uneven surface that requires further grading.
  • Requires relatively large, open areas for efficient operation. Size and shape of site can limit use of RDC/HEIC.

Vibratory Compaction - Smoothdrum, Padfoot, Tandem, Combination, and Vibrating Multi Tyre Rollers.

A yellow circle sits above a horizontal yellow line, with five curved yellow lines below—reminiscent of a Compaction Matrix reflecting or creating ripples in water—all on a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Compaction of granular soils (sands, gravels, crushed rock) for subgrades, base courses, and foundations.
  • Key method for compacting asphalt layers (breakdown and intermediate passes) in road and pavement construction.
  • General earthworks where granular materials need densification.
Medium, typically 0.3 – 0.6 meters (1 – 2 ft) per lift, depending on roller size and soil type. Granular soils (sands, gravels), crushed rock, and asphalt.
  • Highly efficient and fast for densifying granular materials, achieving high densities quickly.
  • Versatile for various project scales, with rollers available in many sizes and weights.
  • Good for a wide range of compaction needs on granular soils and asphalt pavements.
  • Effective on highly cohesive (clay) soils; with specialised vibratory rollers with sheepsfoot / padfoot drums.
  • Can generate significant ground vibrations, which may be a concern near sensitive structures or adjacent utilities.
  • Optimal performance requires good drainage in the material being compacted (OMC).

Oscillation Compaction - Smoothdrum and Tandem Rollers

A large yellow circle sits above a yellow horizontal line, with concentric rings below resembling a Compaction Matrix or ripple effect on water, all on a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Compaction of hot asphalt pavement layers, especially surface and intermediate courses where smooth finish and gentle action are desired.
  • Compacting granular bases and sub-bases in built-up or sensitive areas (e.g., near buildings, bridges, utilities) where traditional vibratory methods might cause excessive vibration transfer.
  • Can be used on temperature-sensitive asphalt mixes (e.g., polymer-modified asphalt).
  • Used in areas where minimal vibration transfer to nearby structures is critical, such as bridges, around utilities, or in urban environments.
Primarily effective for shallow to medium depths of asphalt layers (typically 0.05 – 0.15 meters or 2 – 6 inches per lift). For granular materials, it can effectively compact typical lift thicknesses in the shallow to medium range.Hot mix asphalt (HMA), granular bases (sands, gravels, crushed rock).
  • Applies a kneading/rocking motion which helps avoid aggregate crushing in asphalt and provides effective compaction in granular materials.
  • Significantly reduces dynamic forces and vibrations transmitted to the subgrade and surrounding structures, making it ideal for sensitive areas.
  • Promotes uniform density and a smooth, high-quality surface finish in asphalt.
  • Effective over a wider temperature range of asphalt compared to conventional vibratory compaction.
  • Can achieve compaction with fewer passes on some materials while reducing stress on the machine.
  • Generally less aggressive for deep lift compaction or initial breakdown rolling on very thick asphalt layers compared to conventional vibratory rollers.
  • Higher initial cost for the specialised roller compared to standard vibratory or static rollers.
  • Though it can work on granular soils, standard vibratory rollers might be more productive or cost-effective for deep granular compaction where vibration isn’t a major concern.
  • Not suitable for highly cohesive (clay/silt) soils.

Static Compaction - Multi-tyre / 3-point rollers

A yellow circle sits centered on a horizontal line with a yellow triangle beneath it, forming a simple abstract balance scale that hints at the symmetry of a Compaction Matrix on a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Compaction of asphalt pavement layers, particularly for the surface layer and finishing passes to achieve a smooth finish.
  • Compaction of fine-grained cohesive soils (clays, silts) where the kneading action or heavy static pressure is beneficial.
  • Used for proof rolling and in situations where vibration is prohibited or undesirable due to nearby sensitive structures.
  • Compacting subgrades and certain granular bases.
Shallow, typically 0.15 – 0.3 meters (6 – 12 inches) per lift.Asphalt, cohesive soils (clays, silts), and granular bases (though less effective than vibratory for deep granular layers).
  • Provides a smooth, high-quality surface finish, essential for asphalt pavements.
  • No vibrations are generated, making it safe for use near sensitive buildings, utilities, or in urban areas.
  • Multi-tyre rollers offer a beneficial kneading action that helps densify cohesive soils uniformly.
  • Relatively simple to operate and widely available.
  • Higher initial comparative cost for the specialised roller compared to standard vibratory or static rollers.

Plate Compactors (up to 500kg, typically vibratory)

Yellow silhouette of a turret-like Compaction Matrix machine with an extended arm on a white background, emitting curved lines below it that represent sonar or radar waves.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Compacting backfill in trenches (e.g., utility installations).Preparation of sub-bases for footpaths, small patios, and landscaping areas.
  • Patching and repairing asphalt surfaces.
  • Compaction in confined spaces and around obstacles where larger equipment cannot fit.
  • Preparing granular bases for small structures.
Shallow (typically 0.15 – 0.3 meters or 6 – 12 inches per lift).Granular soils (sands, gravels), asphalt patching, small aggregate bases.
  • Highly manoeuvrable and portable, excellent for confined spaces and tight access.
  • Lower risk of over-compaction or damaging nearby structures compared to heavy rollers.
  • Effective for surface densification and leveling of small areas.
  • Relatively lightweight, easy to transport, and operator-friendly.
  • Offer good efficiency for granular materials.
  • Not suitable for cohesive soils; its primary application is asphalt compaction and granular soils.

Rammers (Tamping Rammers / Jumping Jacks)

A yellow silhouette of a jackhammer breaking through a surface, with curved lines below illustrating vibration or sound waves—symbolizing the powerful force of a Compaction Matrix—on a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Compaction in extremely confined or narrow spaces, such as very narrow trenches, utility pits, and around pipes or foundation elements.
  • Compacting backfill around small footings and foundations.
  • Small patching jobs where precise  compaction is needed in a very small area.
Very shallow (typically 0.1 – 0.2 meters or 4 – 8 inches per lift).Cohesive soils (clays, silts), mixed soils, and some granular materials (though less efficient than plate compactors for granular).
  • Excellent for extremely confined or difficult-to-access areas where no other machine can fit.
  • Highly effective on cohesive soils due to their high impact force and small tamping foot, providing good compaction for such materials.
  • Ideal for compacting directly around obstacles like pipes, conduits, and structural columns.
  • Very portable and relatively easy for one person to operate.
  • Can be slower in achieving density on very stiff or cold asphalt mixes.

Rapid Impact Compaction (RIC)

A yellow silhouette of a machine with a robotic arm on tracks, positioned above a line, with curved lines below suggesting sonar or radar scanning, representing the Compaction Matrix process.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Improving ground strength and stiffness (increasing bearing capacity, reducing settlement) for foundations and infrastructure.
  • Mitigating liquefaction in seismic zones.
  • Densifying various fill materials, including waste and remediation sites.
  • Offering an efficient alternative to excavation and replacement.
3 – 5+ meters (9 – 15+ ft).Loose granular soils (sands, gravels), and uncontrolled fills.
  • Achieves good densification depths for intermediate to deep improvement.
  • Allows for targeted improvement of specific problematic zones.
  • Slower production rates over very large areas compared to continuous rolling methods like RDC/HEIC.
  • Generates significant ground vibrations, necessitating caution and monitoring near sensitive structures.
  • Limited effectiveness in highly cohesive (clay) soils or highly saturated silts/clays.

Dynamic Compaction (DC) - Crane Dropped Weight

A yellow silhouette of a crane with a magnet, lifting above a horizontal line with curved signal lines beneath—symbolizing the Compaction Matrix—on a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations
  • Densification of large areas of loose granular soils and fills for heavy structures.
  • Major infrastructure projects such as industrial complexes, heavy warehouses, port facilities, airport runways and aprons, large storage tanks, and large-scale embankments for roads and railways.
  • Improvement of uncontrolled fills, demolition debris, and even sanitary landfills to support future construction.
  • Mitigation of liquefaction potential in loose, saturated granular soils, especially in earthquake-prone areas.
  • Collapsing voids in shallow karst (limestone) geologies to reduce sinkhole potential.
  • Treating marginal sites to enable the use of shallow foundations, avoiding the need for deep excavation or piling.
 Dynamic Compaction is known for its ability to improve soils to significant depths, often ranging from 5 to 15 meters (20 to 65 ft), and in ideal conditions, even deeper (up to 30 meters / 100 ft).
The actual depth depends on factors like the weight of the pounder, drop height, number of impacts, grid spacing, and soil characteristics (especially permeability and fines content)		 Loose granular soils: Sands, gravels, silts (especially those with low fines content).
Uncontrolled fills: Demolition debris, industrial waste, construction rubble, mixed fills.
Landfills: Old refuse and industrial waste dumps (though treatment is complex and depends on waste composition).
It’s less suitable for highly cohesive (clayey) soils as they tend to absorb the energy and prevent deep penetration, and pore water pressures can build up excessively without proper drainage. If used on cohesive soils (often termed “Dynamic Consolidation”), it requires rest periods for pore water pressure dissipation
  • Achieves deep densification in situations where other methods are not feasible or economical.
  • Highly effective in increasing the density, stiffness, and bearing capacity of a wide variety of problematic granular soils and fills.
  • Reduces post-construction settlement significantly.
  • Cost-effective for treating large areas and deep problematic layers compared to deep excavation, removal, and replacement, or deep piling.
  • Can often treat a wide range of highly variable, unclassified, or contaminated fills, potentially avoiding their costly removal.
  • Relatively simple in concept, making on-site adjustments possible based on observed ground response.
  • Generates very high ground vibrations and noise, which can be a major concern near existing sensitive structures, utilities, or residential areas. Exclusion zones (often 15-30m or more from buildings) are typically required.
  • Not suitable for highly cohesive (clay) soils where the energy is absorbed too quickly and water cannot drain effectively.
  • Can cause surface loosening during the initial passes before the deeper layers are consolidated.
  • The process can be time-consuming due to the grid pattern and multiple passes, and requires precise planning and monitoring.
  • Requires a large, open work area with sufficient overhead clearance for the crane and dropping weight.
  • Groundwater levels must be carefully managed; it’s generally most effective when the groundwater table is at least a few meters below the surface.
  • Requires rigorous quality control through in-situ testing (e.g., CPT, SPT, plate load tests) before, during, and after compaction.

Surcharge Compaction - Preloading

A yellow geometric shape, representing a Compaction Matrix, is centered with four large yellow arrows pointing downward toward it from above, against a white background.

Typical uses / Applications

Depth of Influence range

Typical Material used

Strengths

Limitations

  • Primarily used to strengthen and reduce future settlement of soft, compressible cohesive soils (clays, silts) and highly organic soils.
  • Common for large embankments, highway approaches to bridges, and foundations on soft ground.
  • Often combined with Prefabricated Vertical Drains (PVDs) to accelerate the consolidation process.
Can improve very deep layers, often extending tens of meters if vertical drains are used to facilitate water expulsion. The depth is limited more by drainage path than energy penetration.Soft, compressible cohesive soils (clays, silts), and organic soils.
  • Highly effective for improving problematic soft, fine-grained soils where other dynamic or vibratory methods are ineffective.
  • Significantly reduces long-term, post-construction settlement.
  • Increases the shear strength and bearing capacity of the treated soil.
  • A non-vibratory method, making it safe for use near sensitive structures or in urban environments.
  • Very time-consuming, with consolidation periods ranging from months to even years, depending on soil properties and the use of drains.
  • Requires significant space on-site for the temporary surcharge fill and its eventual removal.
  • Involves substantial costs for placing, maintaining, and removing large quantities of fill material.
  • Ineffective for densifying granular soils, as it relies on water expulsion from fine-grained materials.