Mixing concrete by hand is a chore. Even if your project is small, like pouring landscaping paths or repairing city sidewalks, it can be time- and labor-intensive to create the perfect mixture. If you don’t mix the ingredients correctly, you could end up with weak, unsafe concrete or inconsistencies that require costly rework.
Using a portable concrete mixer is an ideal solution for small- to medium-sized projects. By mixing concrete in a mixer, you can take the strain out of mixing concrete and streamline operations.
In this article, you’ll learn how to mix concrete in a mixer to get the ideal consistency for pouring concrete.
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What Is a Concrete Mixer?
A concrete mixer is designed to take the labor out of mixing concrete. All concrete mixers feature a drum that has paddles inside. The paddles mix the water, sand and aggregate together to create wet concrete. Most mixers use an engine to turn the drum, but there are hand powered ones, as well.
Portable Concrete Mixers: Ideal for Small Mixing Jobs
Portable concrete mixers have a capacity of 3 to 9 cubic feet. They are ideal for smaller concrete jobs, such as sidewalks, concrete repairs or small construction projects. Their compact size also makes them great for areas that a mixing truck can’t access.
Renting a portable mixer gives you the following benefits without the long-term hassles of equipment ownership:
- Flexibility: Take on small projects or mix concrete in hard-to-reach areas with ease.
- Less Waste: By mixing smaller batches as you need them, portable mixers minimize the risk of overproduction and wasted materials.
- Cost-Effectiveness: Renting a portable mixer and mixing close to where you need to pour can help you save on project costs and eliminate the ongoing costs of equipment ownership, such as storage and transportation.
How to Mix Concrete in a Mixer: A Step-by-Step Guide
The following steps will help you correctly mix concrete using a portable concrete mixer. But keep in mind that each type of bagged concrete mix and portable mixer model is different. Before you get started, read the instructions for your mix and mixer and collect the materials you’ll need.
Materials You’ll Need:
- Bagged concrete mix (cement and aggregate)
- The right amount of water
- Concrete mixer
- Plastic wrap or a lid for the mixer
- Personal protective equipment (PPE)
1. Calculate the Amount of Concrete You Need
The first step to mixing concrete is to make sure you have enough water and bagged concrete mix to create the amount of concrete the project needs.
To figure out how much concrete you need, you just need to calculate the volume, or cubic feet (ft³), of the space you’re filling and add a buffer to make sure you’re never short.
How to Determine How Much Concrete You Need:
- Measure the length and width of the space in feet.
- Know how deep the concrete needs to be, in feet. (Example: 6 inches = 0.5 feet)
- Multiply to find the volume of the space you’re pouring in cubic feet: Length × Width × Depth = Volume
- Add 20% to make sure you have slightly more concrete than you need, in case there’s any issues during the job. You don’t want to botch a project that is mostly finished by not having enough concrete to complete properly.
Example:
You’re pouring a patio that will be 10 feet wide, 10 feet long and 6 inches deep.
- 10 ft. × 10 ft. × 0.5 ft. = 50 ft³.
The patio needs at least 50 cubic feet. Now, add 20% to create a buffer.
- 50 ft³. + 20% = 60 ft³.
You’ll need to mix 60 cubic feet of concrete with your mixer.
2. Add Some of the Water and Dry Materials
Once you know how much concrete you need, it’s time to get the water and start adding materials into the mixer.
- Read the Labels and Measure the Water:
- Look at the labels on the bags of concrete mix to find out the amount of water you’ll need. Every mix is different and may require different amounts of water.
- Look at the mixer’s labels or owner’s manual to find out how much mix can fit safely in the drum. The mix needs room to move, so put less mixture into the drum than the total volume of the concrete mixer.
- Wet the Mixer: Before you add the dry materials, pour about 50% to 75% of the water into the mixer. This will help prevent concrete from sticking to the sides of mixer and make cleanup easier later.
- Add the Dry Materials: Now, pour the dry materials into the drum of the mixer.
3. Cover the Mixer Opening
Use a lid or plastic wrap, such as a flattened garbage bag taped to the mixer, to seal the opening of the drum before you turn it on.
If you do not cover the opening before mixing the dry materials, much of it will be lost in dust that flies out. In addition to losing the materials, this will create quite a mess to clean up later.
4. Run the Mixer for 3 Minutes
Double check the mixer to make sure it’s on a firm, level surface. Then turn it on and run the mixer for about 3 minutes to fully combine the dry materials.
Monitor the concrete mixer to make sure the drum stays as close to horizontal as possible without causing any of the mixture to fall out.
5. Add the Rest of the Water and Continue Mixing
Slowly add the remainder of the water to the mixture and continue mixing until you’ve reached the right consistency. It usually takes about 5 minutes of total mixing time for the concrete to reach a thick — but not brittle — texture.
6. Test the Concrete’s Consistency
The mixture is ready when it has the texture of thick oatmeal. To test the consistency, turn off the concrete mixer, and — using gloved hands or a scoop — pick up some of the wet concrete.
- Ideal Consistency: The concrete should be able to hold its shape when pressed into a ball but still soft enough to shape easily without crumbling.
- Too Dry: The mixture is too dry if it breaks apart when pressed into a ball or is too stiff to work with.
- Too Wet: The mixture is too wet if you pick up a handful and it runs through your fingers. If the mixture is too wet, it won’t set properly and will be too weak.
7. Adjust and Re-Test as Needed
If your mixture is not the ideal consistency, here’s how you can fix it:
- If the Mixture Is Too Stiff or Brittle: If the mixture is too dry, add a little bit more water and re-mix. Then test it again. Once it is the right consistency, you can pour it into place.
- If the Mixture Is Too Runny: There’s too much water. Too much water significantly weakens the concrete’s strength and increases its drying time. Unfortunately, adding more dry materials can create inconsistent and unpredictable results. It is often better to throw out the runny mixture and start again.
5 Quick Tips for Mixing Concrete Safely
As with any project, it’s important to keep your team and project site safe. Working with concrete is no exception. To work effectively, use the tips for mixing concrete below and follow all safety recommendations, such as OSHA’s Concrete and Concrete Products guide.
- DO Wear Personal Protective Equipment (PPE): Wearing gloves when working with concrete is a must because wet concrete can quickly dry out and damage any skin it comes into contact with. The mixing process is also very dusty. Wear eye protection and a mask, such as a NIOSH N95 face covering, to protect your eyes and airways.
- DO Keep the Mixer Stable and Level: The mixer needs to be on firm, level ground so that it does not tip over during operation, spill the contents, or cause wear and tear on the machine.
- DO NOT Overfill the Mixer: Overfilling the mixer can cause several problems. It can overwork the motor, possibly damaging it. Overfilling can also cause the concrete to dry out before it finishes mixing or cause the mixer to topple over and spill.
- DO NOT Leave the Mixer Unattended: It is important to have someone monitor the concrete mixer while it’s running. The attendant can make sure the mixer stays balanced while making sure the concrete doesn’t dry out and ruin the batch or the mixer.
- DO Properly Clean the Mixer Between Batches: Do a quick clean between batches to keep leftover materials from impacting later batches. To clean the mixer, run the mixer with some water and a little bit of sand or other aggregate, then pour it out in a proper waste bin. Use a stiff brush to remove any residue that’s stuck to the inside.
Rent Premium Concrete Mixers from Herc Rentals
Portable concrete mixers are a perfect addition to any project where you need to pour concrete in a small or hard-to-access area. When it’s time to gear up for your next project, contact the equipment experts at Herc Rentals.
At Herc Rentals, you’ll find the right concrete mixer for your job from manufacturers you can trust. Our fleet is kept in excellent condition so you can be confident they will help support a safe and efficient project site. Plus, with our equipment transportation and repair services, your team will be freed up to focus on what they do best.
Explore our selection of top-quality portable cement mixers or call 888-777-2700 to talk to a specialist today.
