A plate compactor is a compaction machine used for construction projects that require compaction. Whether you're laying a concrete slab, building a patio, or backfilling a trench, plate compactors are required to compact your foundation material.
They smoothen and level the soil in preparation for landscaping, paving, and other home improvement projects.
Also called a wacker plate, there are different types and they come in different sizes. In this post, we'll be looking at the different types, how they work, and how to use them.
Why Proper Compaction is Necessary
Proper soil compaction is necessary to provide a base that adequately supports a foundation. When there is inadequate compaction, the soil has larger pores and a lower density. Since large pores help to move water through the soil efficiently, the soil's infiltration and drainage rates increase.
This causes it to shift, contract, or expand unevenly. It leads to uneven settlement of the foundation which can cause structural damage.
With proper compaction, however, the soil particles are well compressed and have less pore space between them. This leads to higher soil density, fewer large pores, and a more even surface. The surface is more compact which helps to prevent damage to the structure.
Interlocking pavers that aren't properly compacted would most likely become unstable. Consider the case of a contractor who is constructing a driveway with interlocking paving stones. If the sub-base isn't properly compacted, both the pavers and foundation will lack stability. This causes shifting and compression that worsen as vehicles with large weights drive through them.
Eventually, this causes grooves in parking spaces and areas that vehicles pass frequently. As the sub-base and pavers continue to shift, the surface becomes uneven. Unfortunately, uneven pavers can cause trip hazards and diminish your driveway's curb appeal.
How Plate Compactors Work
A plate compactor's job involves compacting soil to create a solid surface that can support a foundation. To do this, they have heavy steel flat plate attached to their bottom. Compactors use a pounding or vibrating action to level the land beneath them.
A plate compactor's steel plate combines its rapid movement with its weight and impact force to compact the soil. The force exerted on the land compacts it while the vibrating plate action encourages the soil particles to move closer. This removes air pockets and provides better soil compaction.
While you can use wacker plates on different soil types, they are more efficient on granular soils. This is because granular soil have more gravel/sand which provides smoother particles. Also, a plate compactor's vibrations settle the soil while it's being compacted.
Also see our article on using a power trowel.
Types of Plate Compactors
There are three categories of plate compactors and they provide results that are slightly different due to their design. They are:
Single Plate Compactors/Vibratory plate Compactor:
They are the lightest and smallest of the three. They only compress(move) in one direction which makes them difficult to maneuver.
Single Plate compactors can exert a force of up to 5000 pounds and can only cover a small area at a time. This makes them the right construction equipment for compacting asphalt, dirt, or gravel.
Reversible Compactors:
These types of compactors can move forward and backward. Hence, they can cover larger areas compared to single plate compactors.
Many reversible wackers can exert a force of up to 9000 pounds. The greater force means they provide deeper compaction which makes them perfect for cobblestones or driveway projects.
Heavy-duty/High-Performance Plate Compactors
Heavy duty plate compactors exert the highest force. These types of machines are great for compacting soils that require a large amount of force to vibrate particles in close contact. A good example is clay soil or any soil that contains clay.
Buy The Bartell Global Reversible Plate Compactor - 3750kg Force
How to Use a Plate Compactor
Below is a step by step guide on how to use a plate compactor:
Step 1: Rake the Ground
It's much easier to push a plate compactor across a smooth surface. Hence, it's important to use a rake to smoothen the ground. For better results, use a wide-toothed rake.
Step 2: Take Safety Precautions
When using a plate compactor, certain safety measures should be taken to avoid injuries or any kind of harm. Be sure to wear the correct safety equipment including work gloves, dust masks, steel-toed boots, earplugs, and safety glasses. Also, don't smoke while using a plate compactor and check to see that there is no fuel leakage.
Step 3: Start the Wacker Plate
Assuming you're using a petrol plate compactor:
- Open the fuel valve by moving the choke lever to the right.
- Set the throttle to idle to prevent your wacker plate from starting at full vibration and click on the "On" position on the power switch to turn on the machine.
- Petrol wacker plates can be started using the rope start method. To do this, hold the pull start recoil with one hand and the control hand with the other.
- Proceed to pull the start recoil to start the machine. Sometimes, it may take more than one pull to start the machine.
When you've successfully turned on the wacker plate, close the choke and set the throttle control to fully open.
When using electric models:
- Get a generator or transformer to plug the plate compactor into.
- When using a transformer, connect it to a 240v electric outlet.
- Using a 110v extension lead, connect the wacker plate to the transformer.
- Locate the control handle and click the green button to start the machine.
Step 4: Compact in Straight Lines
When the compactor is turned on, its rapid vibration causes it to move forward across the surface. Take the following steps to compact in straight lines:
- Hold the handle to direct its movement in a straight strip to make the first pass.
- Move the machine back and forth in the same corner to compress the area properly.
- Position the compactor in a way that allows you to move perpendicular to the previous straight line. It is called the overlapping pattern and helps you achieve proper compaction.
- Repeat the process a couple of times to ensure proper compaction. The more the better if you're dealing with high moisture content soil.
Step 5: Switch off the Wacker Plate
When you've successfully compacted the entire area, it's time to switch off your wacker plate. To do this, return the throttle to idle. This stops the machine's movement. Wait for a few minutes before turning off the Power Switch.
Finally, check to see if the choke is fully/partially open. If it is, close it.
What to Consider Before Choosing a Plate Compactor
Whether you're compacting granular soils, paving blocks, or cobblestones, there are a few things to consider when choosing a plate compactor for a job. They include:
- Operator Comfort: When switched on, wacker plates vibrate. This makes them a bit tricky to handle. However, some wacker plates come with handles that have vibration isolators. Vibration isolating steering handles help to reduce the vibrations to ensure they are handled safely.
- Fuel Source: Most vibratory plate compactors are powered by gasoline or diesel. Others are powered by electricity. When choosing your preferred plate compactor, it's important to consider which fuel source is readily available to you. If you're working at a site with no electric options, it's best to not buy an electric compactor.
- Easy Transport: Plate Compactors aren't just any equipment you can easily take out of your toolbox when you need to work. These are large machines and would need some heavy lifting to get them to the job site. That said, you can make your life easier if you choose a compactor with lift handles. These handles make it much easier to move the machine to where it's needed.
- Water Tank: Some vibrating plate compactors have water tank capabilities. This means you can fit water tanks on them to create a layer between the sticky material and the plate. If your project involves working with sticky materials like asphalt, it's best to get a vibrating plate compactor that has water tank capabilities.
- Size of Project: Before choosing a compactor with vibrating plates, it's important to consider the project size. If you're compacting a small project, it's better to choose a smaller plate size for convinience.
Can you Compact Sand Without a Compactor?
Yes, it's possible to compact sand or clay without using a plate compactor. However, you'll need to replace the pores in the ground with the right amount of water.
For quick DIY jobs without the right equipment, here are a few tips on properly compacting a surface without a plate compactor:
- Mist water over the surface using a low-pressure nozzle on a garden hose.
- Wait for about an hour to allow the water to soak into the ground.
- When the water has drained into the ground, water the sand again until there's a pool of water on the soil's surface. For better results, continue to trickle water over the surface until it can no longer drain into the soil quickly.
- If you're working with clay soil, you'll need to repeat this process several times since clay is less porous than sand.
- When you've drained enough water in the sand, you can compact the wet soil with a compaction equipment like hand tamper, lawn roller, or walk over the ground with your legs.
