12 tips for mixing concrete off-grid on a budget


Concrete Mix

Some people hit a ‘concrete wall’ when thinking of how they can tackle the task of pouring concrete. This can be a daunting task for some, however in reality it’s not a difficult task at all, and can be done in an inexpensive way.

Pouring concrete is a task which anyone with half a brain can tackle without a problem, and anyone with a full functioning brain can complete the task well. It doesn’t matter whether it’s just a concrete floor or the footing for your cabin. I’ll be providing a handful of different tips which you can use to do this efficiently.

Forms

The first step off this long process is preparing your equipment and creating your forms. Dimensional lumber can be used for forms, and they work very well. A straight bit of lumber is desirable. I’d recommend 2-inch-thick boards 2×4 2×6… etc.

These forms will have to be reinforced using sturdy stakes. When mixing concrete, I use metal concrete stakes. I use these metal concrete stakes. I buy mine from Amazon as they offer quick delivery, and ensured that they arrive intact.

Alternatively, wooden stakes could also be used, however I like the higher quality stakes. Keep in mind that when concrete is poured into your forms – pressure will be applied outward onto the forms; therefore, they must be staked into the ground. If you purchase the metal concrete stakes which I’ve recommended, there will be holes which you can put nails through, to nail into the forms.

If you are able to dig a narrow trench, it’d be a good idea to use dirt as the form, up to level ground. You would then use forms for the footer above the ground. If an end form is required, I’d recommend that you build the forms from 4-inch-thick plywood. This should work effectively, even if you get slightly less thick plywood. The important thing is that your forms are braced at all levels.

How wide should footer be? You’ll need to take the soil type into consideration when deciding how wide your footers should be. Another factor which will dictate how wide footers should be is the length of your building (How tall). If you’re cabin is 1 story tall then you’ll want your footer to be around 10 inches wide.

How deep should the footer be for a building foundation? You should base how deep your footer should be for a foundation, off the frost depth in your region. This is the depth as which the ground freezes. Now, you may be asking yourself, how do I find the frost line depth in my area? You can find this information at your country office – or if you’re in the USA, you can take a look at this map. It is important that your footer starts below this depth so that your building doesn’t move in the winter.

How thick should concrete floor slabs be? You want your concrete slabs to be around 4 inches, this is the optimum thickness, however this should be adapted depending on what you’ll keep on it. For example, if you intend on having a caravan parked on it – you’ll want a couple extra inches on top.

Outside Temperature

What is the ideal outside temperature for concrete? There is an optimum temperature for pouring concrete. This is around 60°F (15.5 Celsius) or higher. This is because if the temperature is too cold, the concrete will be harder to set-up. If it’s extremely cold, the concrete could freeze and shatter. This would cause unwanted cracks which you don’t want. Therefore, I’d stick with the recommended temperature for pouring concrete.

How hot is too hot for pouring concrete? You want concrete to be somewhat warm as it speeds up the time in which concrete cures. It is also possible that if the temperature is too hot, the surface could cure faster than the underlying concrete which will lead to cracking. To prevent this from happening you should spray some water on the surface of the concrete every couple of hours to keep it cool and prevent it from cracking.

Reinforcing Concrete

Concrete is a solid material which copes well with compression however it struggles with resisting against expansion. Therefore, concrete should be reinforced with metal to support the concrete shape whilst its under stress. What should I use to reinforce concrete? There are multiple different materials which I use when reinforcing my concrete.

I use Rebar in footers, and occasionally I’ll use it in slabs. When utilizing Rebar in a slab, I use Rebar 3 which refers to its thickness. When using Rebar for footings, I use Rebar 5. A thicker piece is required to provide extra strength. I also use Rebar 4 for walls.

When building a footer, I place a piece of rebar, the length of the footer close to the bottom – however off the ground so that the concrete surrounds it when finished. I also place a bit of rebar, vertically from the height of the footer, every 3 feet. For every one and a half feet, I also add a bit of rebar horizontally. An alternative way to reinforce your concrete is to purchase wire mesh which you can find in local stores or from online shops. Wire mesh works very well as it provides tensile strength.

For added strength I sometimes throw some large rocks/stones into the footer. If you’re going to also do this, then ensure that the material you throw in is durable and strong. The main advantage of filling your footer with rocks is that it means that you can get away with less concrete mix as thee extra space is being filled. Being able to use less concrete mix is useful as it’s a lot more expensive than rocks which you can find anywhere for free.

When to use Expansion Joints

When should I use expansion Joints? The answer to this question is relatively simple, you’ll want to use expansion joins when your pouring a large slab.

When the temperature of concrete fluctuates, the concrete will contract and expand. Therefore, when pouring large slabs, cracking may occur naturally. Therefore, room should be created so that the concrete can contract.  This space can be created using expansion joints.

When calculating the length between expansion joints you’ll need to take the thickness of the slab into account.

Thickness of Slab (Inches) Multiplied by 2 = Space between Expansion Joints (Feet)

Get an Inexpensive Cement Mixer

Can I mix cement without a cement mixer? You can mix cement yourself if you really don’t have the budget to purchase a cement mixer however it will take a lot more time and a whole lot more manual work. You could so this by emptying the cement mix into some sort of large container, adding water and stirring with a shovel.

I’d really recommend you just invest into a cement mixer, it’ll save you so much sweat and time. There are cheaper alternatives however they may not be of the same quality – therefore I’d just play it safe and purchase the mixer I’ve recommended.

Which Cement Mixer should I get? I’d recommend you purchase this cement mixer. This is a great cement mixer and I’d highly recommend that you invest into it. It’s very strong and sturdy, this can last you for many years if properly maintained. It’s well worth the money, you’ll be saving a lot of time, sweat and tears.

Firstly, I pour some concrete mix into the mixer, followed by about a gallon of water. I then turn it on and slowly pour in the rest of the mix. Whilst dumping the rest of the mix, it’s a good idea to continuously spray water into the mixer. I continue to do so until it’s at the right consistency, when it flows smoothly. You don’t want it to be too watery otherwise it will be too thin, and you’ll have to add more cement mix.

I’d recommend you continue to keep the cement mixer running whilst you pour out the concrete. Doing so will allow you to get every bit of concrete out from the mixer.

To power your cement mixer, you’ll need a generator. There are many different types of generators which you can purchase – most will do the job as long as they’re powerful enough. I use this generator, It’s perfect for the job.

Get a Cement Vibrator

I’d highly recommend that you purchase yourself a stinger. This is a tool which vibrates and settles the concrete. To use it, you just put the vibrating end of the tool into the concrete, it will vibrate and settle the concrete. It’s extremely efficient way in settling your concrete and a worthwhile investment.

To settle your concrete manually without a vibrator, you’d have to continuously stab your shovel into the concrete to aid in the settling process, however this is extremely exhausting as well as inefficient. It’s just a much better idea to invest into a cement vibrator, they’re relatively cheap and inexpensive.

Which cement vibrator should I buy? I’d highly recommend this cement vibrator. It’s never let me down and works extremely well – much better than some more expensive alternatives that I’ve tried. This does the job perfectly, if you’re not using it commercially (meaning, everyday). Using this vibrator has saved me so much time, and made the settling process easy.

Water

I’m unfortunate enough to not have a water well. This is why I to store large amounts of water, utilizing 275 gallon water tanks. You can read about how I handle my water situation here. I hook up a garden sprayer to my water tank and continuously spray water into the mixer as it works. I have a full article in which I describe my water storage situation.

Create a makeshift cement chute

When pouring concrete into a footer, you’ll want to create a cement chute unless you plan to purchase one. This is for obvious reasons, you don’t want your mixer to fall into your footer. Cement mixers are expensive bits of equipment which could easily break if dropped from a significant height – you also risk spilling all your cement and creating a huge mess. Because of this, it’s better to be safe than sorry.

Your makeshift cement chute can be built from most materials, as long as it has a smooth surface and no holes/gaps, it should work. I often use bits of scrap metal and create a slight ‘U’ shape in the metal.

Add Grading to your Slab

When creating concrete slabs, you should add some grading, or create a slope in order to stop water from pooling.

When creating huge slabs, you’ll want about 1/7 of an inch for every foot. Whereas for small applications you’ll want about ¼ inch for every foot. When performing the grading on the inside of your footer, every couple of feet.

Smoothing the top of your slab (Screed)

What is the purpose of screed concrete? You’ll want the tops of your slabs to be leveled out and smoothed, this is when you’ll need to screed it. The screeding process consists of cutting off excess wet concrete from the surface of a concrete slab to acquire a smooth state.

You can begin this process with little to no investment. Just grab a straight plank and drag it back and forth over the concrete. This with smooth it out. Continue to do this until your concrete is reasonably flat. It’s okay if it doesn’t look perfect yet as you’ll finish it off in the next step.

How to finish off your concrete slab

To begin finish flattening out your concrete you should use a concrete float. Just like you did with the plank of wood, you drag it across the top of the concrete to smooth it. Any concrete float will do, however the bigger the better as it will require less dragging. I use this concrete float. Very cheap and inexpensive.

After you’d flattened out the concrete using the concrete floater, you’ll want to finish it off with a steel finishing trowel. You don’t have to but if you want the best out of your concrete, you’ll want to complete this task. Just like you did with the concrete floater, you just drag it along the surface to smoothen it out.

Your concrete is now ready!

After the finishing process, your concrete is now ready. Just let it dry and you’re good. If you’ve purchased all the gear I’ve recommended, then you’ll be able to mix your concrete efficiently. Hopefully this post has made the process a lot easier for you.

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