Concrete is to Cement as Bread is to Flour
There is a common misconception that concrete and cement are interchangeable terms for the same substance, but that could not be farther from the truth. And when you are made aware of this, you see the misuse of the word 'cement' EVERYWHERE. Generally, people know that both materials are used in every day structures - in our houses, in our roads, and in the stores and offices we frequent, but their differences are hardly ever considered, and barely known outside of the construction industry.
CONCRETE is a mixture made of (very broadly speaking) aggregate, water and cement. Concrete can also include additives, admixtures, coloring agents, etc. to help improve its performance or allow it to be placed in more extreme conditions. More on that in another post.
CEMENT is a binder, and only makes up roughly 10% to 15% of the concrete mixture. If you had concrete without cement, it would just be a wet pile of aggregate.
History of Cement
Already on the edge of your seat aren't you?
Portalnd cement was first made in the 1800's in England and was named for its similarities to rocks found on the island of Portland, close to England. Joseph Aspdin experiemented with different mixtures before finally producing what we currently know as cement: a combination of limestone, clay, shells, and sand that are crushed together and heated into a fine powder. When mixed with water, cement cures and hardens over time.
Then How Do We Get From Cement to Concrete?
As we said above, cement is the binder, its what holds the concrete together in whatever shape we form it into. However, as soon as the cement is mixed with water, a chemical reaction begins to set the cement. This is why you often see concrete trucks spinning their drums as they drive down the road - it helps to keep the concrete mixture from setting before it gets to the site.
Fun sidenote: Concrete is continually curing for years after it is placed, so while we commonly test concrete at the 28-day mark to see if it has come up to its design strength, it will continue to cure and become stronger (if all goes well) for years.
'Then what is Ready-Mix?" You May Ask
Ah-HA! This comes down to the two main ways you can get concrete to a construction site. You can mix it on site, which means the various components that are utilized to make concrete are delivered to the site individually. Whereas Ready Mix is when a concrete manufacturer mixes the materials at their plant and ships it to the site in trucks. This process generally limits the likelihood of material contamination, increases efficiency of concrete placement, and obviously doesn't require the same amount of staging area on site as its site-mixed counterpart.
Thank you to Knights Companies for providing the basis of this post. Knight’s Redi-Mix focuses on commercial, residential or utility use concrete that is environmentally conscious and carefully mixed for each project in our South Carolina batching plants.
Contact Sharon Benzenberg at sbenzenberg@knightscompanies.com with your next concrete order.