Concrete Explained:

The basics Concrete is the rock we make ourselves. It is the foundation of modern civilization, from sidewalks and skyscrapers to basements and bridges.

But what is it?

Concrete is fundamentally a combination of two elements: rocks and glue.

The “rocks” are the aggregates, a mixture of sand, gravel, or crushed stone. The “glue” that binds everything is cement.

Cement and concrete are not the same. Cement is a powder that serves as the binder. It, along with water, forms a paste that coats each piece of aggregate. It then dries, forming a solid rock-like mass.

This powder is called Portland cement and it is the most common.

How Concrete is Made and Used:

If you have a DIY project, you can buy concrete in small bags from a hardware store. For large jobs, it is delivered in large rotating trucks—often called “cement mixers” which keep the concrete mixture wet and ready to pour.

To create quality concrete that is strong and dependable, the ingredients have to be mixed properly. The aim is to get a thick and pourable liquid. It can be shaped into different forms or molds. It is always a race against time since it can take a couple of hours for the cement to set. For some jobs, like repairing a road, rapid-setting cement is used.
In factories, the concrete mix is made drier to be pressed into forms for pre-made items like concrete blocks and wall panels.

The Secret to Strong Concrete:

Curing Pouring concrete is only half the job. The true transformation occurs during the curing process when the concrete hardens and gains strength.

This isn’t a rapid process. Concrete hardens and gains strength slowly. Most of the hardening occurs within the first month, but even after a year, the concrete will still gain strength.

The first few days of curing is the most critical. The concrete must remain wet and fully hydrated to gain strength. If it dries out too quickly during the first few days of the curing process, the concrete will be weak, and prone to cracking.

To ensure the concrete does not lose moisture, professionals take the following precautions:

They spray the concrete with curing compounds that form a moisture-retaining seal.

They build small ponds of water on the surface of flat concrete to keep the surface wet during evaporation.

They cover the concrete with plastic to hold moisture in.

This attention to curing fully develops the concrete and ensures it will remain in good condition for the lifetime of the structure.