The best way to mix cement? This is a good question, and it is hard to give a precise answer. Different people have different recipes for the same concrete, and different formulas for the same kind of concrete.

But I can give you a hint: if you want to mix concrete as cheaply as possible, mix it as long as possible.

Some people think that cement is made by heating limestone, which is limestone’s job description, and adding water. More correctly, you heat limestone (calcium carbonate) in a kiln at 1,000 degrees Fahrenheit until it melts, and then add water to make a slurry. You might start with 40 pounds of limestone and end up with 10 pounds of slurry: that’s the cheapest way to produce cement.

If you’ve got lime-rock in your backyard you don’t have to pay someone else to chip it and deliver it to your site. If you’re making bagged cement, you can make bags yourself with your own material; they’ll still be cheaper than bags made from processed material.

To make a cement mixture that lasts as long as its ingredients do, you need to mix it properly. The first step is to mix the ingredients thoroughly so the cement will be sure to set. The second step is to mix the ingredients until they are completely mixed and evenly distributed. The third step is to wait for a while so the cement can’t settle.

There is no better way to mix cement than the way the ancient Romans did. The Romans mixed their cement with a 2:1 mixture of volcanic ash and lime, by grinding the ash into a fine powder and then adding it to water. There was no scientific understanding of why this worked, but it was a simple mix that worked, and it lasted for about 1500 years before someone finally invented portland cement.

The modern mixture of portland cement with sand is much weaker than the old Roman mixture, and most building codes don’t require it. If you have an older house and want to fix it up, you could use Roman cement, but if you are going to live in your house for a while you might as well build it with portland cement. It’s much better.

The answer is likely to be: until you need another bag.

You see, in the real world cement is not a homogeneous solid. It has very different properties depending on how it’s made and what other materials are mixed in with it. The more exotic ingredients, the less predictable the results.

Even within a country, there are differences: one kind of cement will work fine for a basement, but not for a swimming pool, and something else will do fine for both.

This lack of predictability is why every home starts with so little cement. If it’s not enough, you can add more; if it isn’t dry enough, you can wait longer; if it isn’t strong enough, you can add sand or Portland cement. But if you want everything to match perfectly, there is no way to get it all done at once.

Cement is a mixture of cementite and silica, and it is hard. But how much harder?

The answer depends on two things: how much cementite there is, and how hard you want your product to be. The harder you want your product, the more cement you will have to mix in. And the more cement you mix in, the longer it will take to set.

For instance, if you want a super-hard material, like marble or diamonds, you have to make it right from scratch. If you want something that is only slightly harder than cement, but still very hard (like a flypaper), you can buy some crushed stone and sprinkle it into your mix. And if you want something softer than cement (say a toy) then you can buy a mixture of other materials and add it in as well.

If all this sounds complicated, it isn’t. All that matters is that your material be hard enough; all the rest can be done easily once you know how to make hard materials.

The mixture of sand, cement and water is the simplest possible concrete, and it is hard. It is much harder to hold all those components together than it is to take a few shovels of sand and a few bags of cement, pour them into a pile, and then throw some water on top. That’s because cement is a viscous material, which means it doesn’t flow easily but sticks to itself instead. This can be very frustrating in construction. Modern buildings are made with concrete in part because it’s stronger than ordinary bricks, but also because concrete has another advantage: it doesn’t crumble when you walk on it in the rain.

That’s not the whole story, of course; concrete also allows buildings to stand up against earthquakes. But there are many other things that could be done better if we could make concrete without having to worry about water leaking through the walls or if we could build buildings that would not collapse after an earthquake hits. And making better concrete would be an interesting problem even if there were no earthquakes to worry about.

So how can we make concrete with less water? Well, maybe we should try making it with something else instead. A great deal of research has gone into finding ways to produce cement without using water at all (e.g