The concrete mixer combines cement, sand or gravel and water to make concrete. Mixing concrete yourself, by hand, without using a concrete mixer can be pretty grueling and challenging work. My dad, a self-professed handyman, used to do it all the time. I can still remember my normally very mild mannered father standing, quietly cursing at a semi-hardened wheelbarrow load of concrete. He'd let it sit too long. Not too long after that incident I arrived home from school and found a brand new, orange portable concrete mixer sitting in the garage. No more hand mixing concrete for him.

Depending on your need, you may want to either buy or rent a concrete mixer. The question is, what sort of concrete mixer best suits your needs? For most handymen or small construction or landscaping businesses a portable electric cement mixer or gas powered concrete mixer is usually sufficient. If you're doing a big job, laying a cement floor or driveway or other heavy construction work, a concrete mixer truck would be what's needed as they can cover a large area in concrete very quickly.

The principle behind both the portable concrete mixer and cement trucks is the same.  The revolving of the drum firstly mixes the ingredients together and secondly to keep the cement from drying and hardening. 

Concrete mixers come in different size drum capacities.  One tip I learned once was to find out the batch output capacity, not just the drum capacity. For example, while a concrete mixer might have a 3-1/2 cubic foot drum, its actual batch output might only be 1-1/2 cubic feet. So, don't go only by the size of the drum, as when mixing cement the drum will be at an angle and will only be 2/3 full.  Some mixers come with a stand which enables the mixer to be upright, meaning you can mix a pretty full drum load. 

Portable concrete mixers are relatively light weight, making them perfect for any small or medium sized jobs.  They are easily operated and manipulated by one person, easy to move from one place to another, and usually can just be rolled from one area to another.  Usually these are either powered by an electric or a gas motor.

A step up from the portable mixers, the towable concrete mixers are a bit heavier duty.  As their name implies, they can be towed behind a vehicle so can be used for different jobs and in different locations. They are usually powered by electric, gas or diesel motors. Some have removable drums so you're able to replace them when and if necessary, other  models have the drums welded on.  The hitch is usually separate.

With both types of cement mixers, the drum has an attached lever that allows the drum to tip down and the cement to pour into a wheelbarrow.

Portable cement mixers are cheaper than the towable ones.  You can usually purchase a new concrete mixer for as little as $400 though prices can go as high as $2,000, depending on the brand and size of the mixer, and how the motor is powered.  Towable concrete mixers start at around $1,800 but can be as expensive as $4,500 or more. Again, this depends on the capacity, how it's powered, and what features it has.

Turn on your mixer and get the drum rotating. Then, start off with about 2 gallons of water and add 1 bag of pre-mix concrete to it. Let it turn a bit, then slowly add the 2^nd bag of cement into the mixer. When that's all added, finish up by adding the last ½ gallon of water to the mixture. Watch it as you're adding it, it should be able the same consistency as cookie dough. If it looks shiny it has too much water added as it should have a dull appearance. If it's too wet just add more of the dry pre-mix to it, till it reaches the correct consistency.

Renting a Concrete Mixer

If you aren't sure whether you want to buy a cement mixer, you might consider renting one. Renting a mixer can cost as little as $50 a day.

A good rule of thumb when deciding whether to rent or hire a mixer is if the amount you pay for renting the it would pay for the purchase of the mixer in a couple of years, you may as well go ahead and buy one. If you're only ever going to rent a mixer once every four or five years, or perhaps only once to do a specific job such as installing a new, cheap bathroom vanity, then you'd be better of just renting it.

Second Hand Concrete Mixers

Incidentally, there's also a very good market on second hand concrete mixers, so you could always think about buying one of those if you didn't want to spend a lot of money on something you wouldn't use that often.

Currently, on Amazon, you can find a used concrete mixer for under $200.