SQ15 PRO
Plate compactor SQ15 PRO
Even base and paver compaction, tireless feed.
View detailsSIMAQ School · Course
Soil compaction
Soil type decides the compactor: granular soil (sand, gravel, base) is compacted by vibration, with the SQ15 PRO plate compactor or a smooth roller, and cohesive soil (clay, silt) by impact, with the SQ60 PRO 2 rammer or a padfoot roller. Work in 20–30 cm lifts, at the right moisture, with 3–4 passes per lift.
The soil decides. Learn which machine to use by soil type, and how lifts, passes and moisture work.
Which compactor do I need?
Answer two things and we'll tell you the exact machine and why.
1 · What kind of soil?
With your area, trench and thickness: lifts, hours and exact model →
The fundamental
Compacting expels air, not water
Soil is three things mixed: grains, water and air. Grains don't compress and neither does water. The only thing you can drive out is air — and everything else follows from that.
Too dry
With no water to lubricate, grains lock by friction and resist rearranging. However many passes you give, air voids stay trapped between them.
On point
A film of water on each grain cuts friction just enough for them to slide and nest. Same machine, same effort, maximum density.
Too wet
Water has filled the voids. Since it doesn't compress, now it's water stopping the grains from closing. The soil pumps under the roller instead of densifying.
The curve that rules your contract
Plot dry density against moisture and a hump appears: the Proctor curve. Its peak is the most that soil can give, and the moisture where it happens is the optimum. When a spec demands “95% of Proctor” it means that peak — and if moisture is off, that 95% doesn't exist that day.
Moisture on point100%of max Proctor
Here the soil gives everything it can. Passes now actually turn into density.
Note the difference between the two soils: granular peaks higher and earlier, with a sharp hump — easy to overshoot. Cohesive peaks lower, later, and flatter: more forgiving on moisture but never as dense. That's why a gravel base is specified differently from a clay embankment.
The theory
Vibration or impact: the soil decides
Granular → vibration
Sand, gravel and crushed base settle with high-frequency vibration: particles rearrange and air escapes. Vibratory plate or smooth roller.
Cohesive → impact
Clay and silt don't respond to vibration: they need impact that kneads the soil. Jumping-jack rammer or padfoot roller. Mixing them up is the most common mistake.
In depth: plate compactor: what it is and what it's for · rammer: what it is and when to use it
| Machine | Soil | How it compacts | Best for |
|---|---|---|---|
| Vibratory plate | Granular | High-frequency vibration | Base, pavers, open areas |
| Rammer (jumping-jack) | Cohesive / trench | Impact (kneading) | Trenches, corners, clay |
| Smooth roller | Granular | Weight + vibration | Roadway, embankment, large area |
| Padfoot roller | Cohesive | Deep kneading | Cohesive embankment, trench |
| Pneumatic roller | Mixed / asphalt | Pressure + kneading (rubber tires) | Thin lifts, asphalt pavement |
Deeper
Energy types and depth
Each machine delivers energy differently — and reaches a different depth.
Depth of influence
Static
Static pressure and kneading, from the roller's weight alone.
Up to ~1 m
Depth of influence
Vibratory
Low amplitude, high frequency: ideal for granular and asphalt.
Up to ~2 m
Depth of influence
Impact
High amplitude, low frequency: kneads cohesive soil deep.
Over 2 m
How do you know if compaction is acceptable?
It's measured against the Proctor test (the soil's maximum dry density at optimum moisture). Sites require a degree of compaction —usually ≥ 95% of Proctor— verified with in-situ density tests: sand cone or nuclear gauge. If it falls short: more passes needed, the lift is too thick, or the moisture is off.
Your machine
How much lift each machine handles
Energy dissipates with depth. Above a certain lift the machine densifies the top and leaves the bottom loose — and that shows up months later, when the floor sinks.
Sand, gravel, base. Compacted by vibration.
| Machine | Energy | Loose lift | Passes |
|---|---|---|---|
| SQRD L71 Ride-on roller 4.2 t | 40 kN · 150 N/cmpublished | 35–45 cm | 4 |
| SQRD L61 Ride-on roller 3 t | 2×30 kN · ≈12.5 kg/cm | 30–40 cm | 4 |
| SQ15 PRO Vibratory plate | 13.0 kN · 5,500 VPMpublished | 25–30 cm | 4 |
| SQRD L51 Ride-on roller 1.5 t | 22 kN · ≈8.3 kg/cm | 25–30 cm | 4 |
| SQ60 PRO 2 Rammer | 13.7 kN · 34×29 cm shoe | 20–25 cm | 3 |
| SQRPTRC L202 Padfoot (trench) | 70 kN · 1.53 t | 20–25 cm | 4 |
| SQRDPWB L102 Padfoot (trench) | 17 kN · ≈5.7 kg/cm | 20–25 cm | 4 |
| SQRDWB L34 Walk-behind tandem | 17 kN · ≈6.2 kg/cm | 20–25 cm | 4 |
| SQRD L41 Ride-on roller 0.8 t | 20 kN · ≈5.7 kg/cm | 20–25 cm | 4 |
“Loose lift” is the material thickness BEFORE compacting; after the passes it drops 15–25%. Ranges are guidance by machine class, derived from published specs.
The test strip: the only truth
No table knows your material. Before committing, compact a strip with the same soil, machine and site moisture, and test density after 2, 4, 6 and 8 passes.
- Density climbs fast on the first passes, then flattens. That knee is your pass count: going beyond it burns fuel and machine hours for no density.
- If the curve flattens BEFORE 95%, passes aren't the problem. It's moisture, or the lift is too thick for that machine.
- Repeat the strip when the borrow pit changes or after rain. Yesterday's soil isn't today's.
Practice
Compact a lift yourself
Pick the soil, how much you lay and which machine. Make the passes and check: the simulator tells you whether the machine was right and whether the bottom stayed loose.
…
Interactive
Lifts, passes and moisture
Move the controls and watch the density change.
Lift thickness25 cm
Recommended: 20–30 cm per lift.
Passes4
Soil moisture
Density reached
Almost — tweak lift, moisture or passes85%
Target ≥ 95%
Compacted
Compact in 20–30 cm lifts: any thicker and the bottom never reaches density no matter how many passes. Watch moisture (optimum is the Proctor value). And passes have diminishing returns: the first does a lot, the sixth almost nothing.
The machine for your soil
SIMAQ compactors
SQ60 PRO 2
Vibratory compactor SQ60 PRO 2
Soil density where the big roller won't fit.
View details
SQRDWB L34
Walk-behind double-drum roller SQRDWB L34
Double vibrating drum for asphalt and base.
View details
SQRDPWB L102
Trench roller SQRDPWB L102
Compacts the trench floor, remote-control ready.
View detailsWatch it
The lesson, on video
How to use the SQ60 PRO L202 remote-control roller
Shorts
Short clips of the gear
FAQ
What people ask most
Which compactor should I use for my soil type?
If the soil is granular (sand, gravel, crushed base), compact by vibration: the SQ15 PRO plate on open areas or a smooth roller on large ones. If it's cohesive (clay, silt), compact by impact: the SQ60 PRO 2 rammer or a padfoot roller like the SQRPTRC L202.
What's the difference between a plate compactor and a rammer?
The plate vibrates at high frequency and settles granular soil on open surfaces. The rammer (jumping jack) strikes and kneads cohesive soil, and fits trenches and corners where a plate won't.
How thick should lifts be and how many passes?
As a rule of thumb, 20–30 cm loose lifts and 3–4 passes per lift; the SQ15 PRO spec sheet lists 300 mm compaction depth. A test strip gives the exact number: test density after 2, 4, 6 and 8 passes and stop where the curve flattens.
Why can't I reach 95% Proctor even with more passes?
If density stops climbing before 95%, passes aren't the problem: it's moisture, or a lift too thick for that machine. Fix the moisture or thin the lift before making more passes.
Can I compact clay with a plate compactor?
It won't work, and it's the most common mistake: clay and silt don't respond to vibration. Cohesive soil needs impact — the SQ60 PRO 2 rammer or a padfoot roller.
How do I know the soil has the right moisture to compact?
If the soil pumps or sinks under the roller, it's too wet; if it stays loose and full of voids no matter how many passes, it's too dry. Optimum moisture is the one that gives peak density on your material's Proctor curve.
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