Materials used in cement

Answer 1

To make cement, well concrete actually, you start with Portland Cement. It contains calcium silicates, "aluminum and iron containing clinker phases" and "other compounds." You add some calcium sulfate to adjust the setting time, and you've got it. Once you have that (if you're doing this in school for a science project forget about making your own; you need a kiln you don't have to make this. Oh, and you can get 94 pounds of it for less than $8 at any lumber yard in the country) add one part cement, two parts sand and three parts gravel plus just enough water to make a product that will stick together if you grab a handful and squeeze it.

There are a LOT of "admixtures" that can be put into concrete. You can use latex, chopped fiberglass, chemicals to make it harden faster or slower, just lots of things. But Portland cement, sand and gravel are the most important parts. Even concrete that doesn't "look" like there's gravel in it, has gravel in it.