What are the ingredients of concrete?

​Concrete is the most significant material in modern construction, and dealing with concrete is all about proportions. Concrete supports residential and commercial buildings, bridges, tunnels, walkways, curbs, sewer systems, etc. Concrete is the building block of progress.

Concrete contains only four basic ingredients: cement, aggregate, sand, and water. Knowing the purpose of each component helps determine the appropriate quantities for a specific circumstance.

Ingredients

Cement
Cement is made out of calcium oxide, an adhesive. Superheated limestone produces calcium oxide. Cement also contains silicon, aluminum, iron, and other additives. After curing, cement keeps the aggregate and sand together.

Cure cement is harder than rock and sand, but not as strong. Cement is hence poor in tensile strength and requires rebar. No problem with torque. Because concrete relies on cement strength to withstand torque.

Remember, more cement does not equal higher compressive strength, but better adherence. Neither are synonymous.

Aggregate
Aggregate (washed, crushed rock) is the component that provides concrete its compressive strength. Concrete is incredibly compressible. The rocks and sand help compress the concrete.

Sand
Sand is not only a filler that eliminates air pockets and gaps between crushed rocks, but it also has a high compressive strength.

Water
Water makes concrete workable by causing a chemical shift in cement's quicklime that lets it stick to rock and sand. Concrete cannot be mixed, shaped, or finished without water.