You’ve always wondered, “What’s the difference between cement and concrete?” Finally, after years and years of thinking this in your head, you decide to Google it. So here we are . . . thinkin’ about random building materials and stuff . . .
At Anchor Foundation Repair, we have been working with these materials for 35+ years for foundation repair as well as our other major services like concrete repair and even for under-slab tunneling. Since we use these materials all the time, we can share our experience and expertise with you on this topic.
This article will define cement and concrete and explain the difference between them. We will explore their properties and varieties a bit and discuss their use within the framework of foundation repair and the other things that we use them for.
I promise it won’t be too *hard* to understand . . . this is the curious and non-technical homeowner version of things.
Is There a Difference Between Cement and Concrete?
All. The. Time. People use the words cement and concrete interchangeably. Someone is just as likely to call your driveway a cement driveway as a concrete driveway. In the English language, they are generally used as synonyms that mean the same thing. But . . . there is actually a difference between them.
Technically, cement is a single ingredient. Concrete is a mixture of several things and cement happens to be one of the important main ingredients in a concrete mix.
Since our language has evolved to include both words as kinda meaning the same thing, neither is wrong to say when you’re talking about your driveway. But one term is *a little more right* and that’s the term concrete.
Cement is a powder-like substance that is manufactured from a bunch of mined and naturally occurring materials. It’s made up of limestone, clay, silica, chalk, iron ore, and even some shells and stuff are in there.
It’s also called Portland cement generically, that is not a brand name or anything. It got the Portland name from the dude that invented it in the 1800s. No, his last name is not Portland. He compared the color of the finished cement to a particular kind of limestone rock on the Isle of Portland (which is somewhere in England). So it also has nothing to do with Portland, Oregon. File this under *fun facts* you never wanted to know but do now.
Cement is considered a binding agent that helps things stick to other things and hardens into a rock-hard material when mixed with water. It is not typically used alone with water. Other ingredients are added to make it work better.
I like to think of all of this in the context of a boxed cake mix. I mean, I like to think of a lot of things in the context of food but I digress . . .
Cement is like the flour in a box cake mix, just one of the things that contribute to the final dessert. Everyone knows that flour is a standard ingredient in cake mix (gluten-free excluded!), but there are other ingredients needed to make that flour into a cake too, which we will check out in the next section.
If cement is like the flour in a box of cake mix, concrete mix is like the whole bag of premixed dry ingredients in the box of cake mix. It’s not just flour in there, it’s sugar and baking soda and other stuff too.
So a concrete mix is all the dry ingredients that go into making the concrete that you typically see in the world in sidewalks, driveways, patios, buildings, streets, etc.
When bought in a store, they might generically call this mix “sackcrete” and two popular name brands you might see too are QuikCrete and Sakcrete – these marketing guys are really inventive with their product names, aren’t they?
What Goes Into Making Concrete?
Now that you know that concrete is a mixture of things, what’s in that mixture? Generally, it’s the Portland cement, an “aggregate” like sand or gravel or both, and water. When you buy a bag of concrete mix at the store, there’s no water in it yet, just the aggregate mix and cement.
Usually, cement makes up about 10 to 15% of concrete, water is about 15 to 20% of the “cake batter,” and the aggregates make up the rest. What’s an aggregate then? Good question.
Aggregates add strength and volume to the concrete mix and help it to be bulkier and take up space. Sand is the most typical aggregate, but different sizes of gravel, from pea gravel to limestone rock to river rock can be added as aggregates to the concrete mix.
So the aggregates add bulk and structure, the cement provides adhesion and strength, and the water makes the magic happen by activating the cement to liquify and then harden. When the concrete is dry, it’s a very strong rock-like substance.
Concrete is durable and can withstand considerable weight and pressure, while also being resistant to erosion because it is stuck together really well thanks to that cement.
Why Are There Different Varieties of Concrete?
You might notice at the store that there’s not just one kind of “sackcrete” or see a bunch of different varieties under the brand names on the shelves in different colored bags. So what’s the difference between all these different kinds?
The difference between varieties of concrete dry mixtures is in one or more of these things:
- The amount of cement
- The types and ratios of aggregate
- The presence of special additives
Sometimes a bit more cement is added to the dry concrete mix. The more cement is included, the stronger the final concrete product will be.
Typical construction-grade concrete is generally around 3,000 PSI – meaning it can withstand 3,000 pounds per square inch of pressure (i.e. that’s a lot). Extra strength concrete mixes can go up to 5,000 PSI and the difference is the amount of cement in the mix.
Types and ratios of aggregates are sometimes for structural purposes, using bigger aggregate to add bulk. Other aggregates are used for cosmetic purposes to create a different appearance in the final concrete product. For example, pea gravel is used to make a rocky sort of surface common in a little nicer residential driveways.
Chemical additives can make the concrete dry faster or slower or be smoother and things like that. Additives can improve or change the concrete somewhat to make it behave better for a particular purpose. For example, a quick-dry concrete mix is good for setting your mailbox post because you want it to dry fast so the post stays straight.
What Kind of Cement or Concrete Are Used for Foundation Repair?
Since we are a foundation repair company, you might want to know specifically how we use cement and concrete.
When We Use Concrete
We make poured 3,000 PSI concrete piers for our slab-on-grade foundation repair services. We use Portland cement in the concrete mix because, well . . . you now know that’s how ya make concrete.
When we are making our drilled bell-bottom piers, we have a concrete contractor bring in the right kind of already mixed and ready-to-use concrete. We pour the piers with the stuff they bring us. This is when you will see the large concrete mixing trucks on-site at your home.
We might use bags of “sackcrete” mix to patch and repair flat concrete surfaces we may have had to break through to get to the locations to place piers for a foundation repair. Bags of concrete mix are also good for smaller projects we do when it doesn’t make sense to bring in a whole truck.
When We Use Cement
Of course we use cement as an ingredient to make our concrete described above. Cement is also a key component in filling the voids under your home after your foundation has been raised: a process called mud-pumping. Mud for mud-pumping is a lot like concrete but not exactly.
We use cement in our other primary services too. Cement plays an important role in our mud jacking process to raise and level sunken concrete. We also use cement to mud-pump and fill in tunnels when we have created a pathway for plumbers to repair your under-slab plumbing leaks.
How Can Concrete Go Wrong?
Despite all the positive qualities of concrete, like strength and durability. Things can still go wrong sometimes. It can be a workmanship issue at the time it is made with mixture ratios that are off or weather conditions that are not optimal at installation time. These can create flawed concrete that is still strong but doesn’t look great.
We talk about a few types of concrete flaws you might see in a home that make you think you have a foundation problem in this article: “Is Foundation Repair Needed: Real and False Problem Signs (Picture Guide).”
Concrete issues can also stem from a problem with the surrounding materials, like when the dirt around the concrete impacts things. Expansive clay soil can cause flat concrete surfaces to sink or crack or both. This can result in foundation settlement and also affect other concrete flat-work surfaces around your home like the driveway and sidewalks.
Can Concrete Be Repaired Once Something Goes Wrong?
Good question. This one is tough to answer because it’s yes and no, it depends on what’s wrong with the concrete and what it’s being used for. In the case of sunken concrete surfaces, there are some solutions.
At Anchor Foundation Repair, we have been working with concrete and cement since 1985 to raise foundations and repair concrete in Bryan, College Station, and other surrounding communities like Madisonville and Caldwell. We are fans of making easy concrete repairs when it makes sense for a homeowner.
Check out this article covering 6 different ways to handle or repair sunken concrete surfaces around your home.