If you’ve ever wondered, “What is the difference between
concrete and cement?” you’re in luck.
The terms concrete and cement are often used interchangeably.
But the truth is, they are not the same. In fact, that “cement”
truck many of us refer to on a job site is actually a misnomer—it
is really a “concrete” truck.
As part of our efforts to spread knowledge about all things
concrete, we are taking a closer look at the concrete vs. cement
battle to set the record straight about these two commonly-used
materials.
Concrete vs. cement: What is the difference? Letâs start with the
cement basics.
Cement is a binding agent which is used to join various
materials together during the construction and building process. It
is an ingredient in concrete (but not the same thing as concrete).
Cement is made of materials rich in calcium and silica, such as
limestone and clay. It is very adhesive, but it is also prone to
cracking (which is why it isnât used very often as a standalone
material).
There are use cases for cement by itself, but typically for
smaller jobs. The most common projects calling for cement are
grouting, some masonry jobs, and concrete repair (where cement is
used to fill cracks or repair crumbling in a larger concrete
structure).
The most common type of cement is Portland cement. It is the
type of cement used to make concrete. Portland cement is usually
comprised of limestone, sand or clay, bauxite, and iron ore. It may
include other materials such as shells, chalk, shale, or
slate.
The various ingredients are mixed and heated to an extremely
high temperature (ranging from 2,700 to 3,000 degrees Fahrenheit)
in a cement processing plant (or more specifically, a cement kiln).
The end product is an extremely hard substance called clinker,
which is ground down to a fine powder and packaged. When clinker is
mixed with water, a paste forms. This paste is used as a binding
agent, and it holds together whatever it has been applied to as it
dries.
There are five types of Portland cement:
- Type I is used for most residential work that doesnât require
any special qualities or properties.
- Type II is somewhat resistant to sulfate, and it is the most
common type used in North America. (Note: Sulfate
contributes to the deterioration of concrete.)
- Type III has a higher strength early on than Type I, making it
easier to remove forms sooner. It is often used when there is a
risk of freezing.
- Type IV has a low heat of hydration. It increases in strength
at a slower rate. It is often used in large construction projects
and industrial applications.
- Type V develops strength at an even slower rate and is used
when severe sulfate resistance is required.
Now, letâs turn our attention to concrete.
Unlike cement, concrete is a building material. As we mentioned,
concrete contains cement, comprising about 10 to 15 percent of the
basic concrete mix. The other primary ingredients are sand, water,
and stone/gravel. Other fine and coarse aggregates are also added
to the mix depending on where and how the concrete will be used.
The water in the concrete mix activates the cement and creates a
binding agent between all of the other aggregates in the mix.
Though you may not consider this an ingredient, there is also
air in concrete mix, referred to as air entrainment. These tiny air
bubbles allow excess water to expand during the freeze/thaw cycle.
If the air bubbles are too large, however, the excess water becomes
entrapped, and the concrete will shrink and then crack.
Now that the difference between cement and concrete is clear,
you can see that when we refer to a cement sidewalk or a cement
mixer, technically, we are wrong. The correct terms would be a
concrete sidewalk and a concrete mixer. There is cement in the
sidewalk and the mixer, but that is not the only component.
Concrete basics: What are the qualities of good concrete?
There are several qualities that characterize a quality concrete
mix that will deliver a long-lasting end product that requires
minimal maintenance. Three stand out to us as critical to evaluate
during the selection process.
Strength
We all consider concrete to be a strong and durable material,
but all concrete is not created equal. There are actually different
ways to measure concrete strength, including compressive strength
(the ability of concrete to withstand loads that will decrease the
size of the concrete), tensile strength (the ability of concrete to
resist breaking or cracking under tension), and flexural strength
(the ability of concrete to resist bending). Certain types of
strength may be more important than others on a given project.
There are also several factors that contribute to the strength
of a given concrete, including the water/cementitious ratio (a
lower water-to-cement ratio makes concrete stronger), the
proportioning of the concrete mix ingredients, mixing time, and
curing methods. We dig into all of these concrete strength factors
in
another article, but the point is itâs important to carefully
weigh the strength properties of a concrete mixture when selecting
one for your construction and building projects.
Workability
Workability describes how easily the concrete can be placed.
Some jobs demand a pumpable concrete or the concrete may need to be
placed in hard-to-reach places. These types of scenarios make
workability increasingly important.
Workability is closely tied to the amount of water used in the
concrete mix. When you use less water, the concrete is stronger,
but it also makes it harder to work with. If youâre unable to get
the concrete in place properly, it doesnât matter how strong it
is.
Thatâs why itâs important to find the right balance between
strength and workability when selecting the ideal concrete mix for
a given project.
Resistance to freeze / thawing and water impermeability
These two qualities are very closely tied together, so we are
combining them for the purposes of our discussion. Water expands
when it freezes. When this happens inside moist concrete, it
creates pressure, which can cause expansion and cracking. Once this
happens, the concrete continues to become more damaged over time as
more cracking and crumbling occurs.
Deterioration of concrete can begin in as little as 28 freeze/thaw
cycles.
Deicing chemicals can make freeze/thaw damage even worse, as
the salt in these mixtures absorbs moisture and makes the concrete
more saturated.
The more impervious concrete is to water and moisture, the more
durable your structure will be and the longer it will last.
Maintenance costs will also remain lower.
The future of concrete: Why Ultra High Performance Concrete raises
the bar
Thanks to advancements in concrete technology, a more advanced
version of concrete is now availableâone that is stronger, more
durable, and freeze/thaw resistant. This revolutionary concrete,
called
Ultra High Performance Concrete (UHPC), is actually similar to
traditional concrete in many ways.
Approximately 75-80 percent of the ingredients in UHPC are the
same as regular concreteâcement, sand, and water. The remaining
20-25 percent of the ingredients are what make it unique.
Integrated fibers made from materials such as polyester, fiberglass
bars, basalt, steel, and stainless steel are added to the mix to
create a progressively stronger end product. The addition of steel
and stainless steel deliver the greatest gains in strength.
UHPC excels in all three of the qualities of good concrete we
just discussed, making it a better choice for construction
projects.
- StrengthâWhereas regular concrete has a
compressive strength of 4,000 pounds per square inch (psi), UHPC
has a compressive strength of 30,000 psi once fully cured. Some
UHPC mix techniques can achieve even higher psi ratings.
- WorkabilityâMany UHPC mixes donât fit the
bill when it comes to workability. Our proprietary UHPC mix,
however, has a working time of more than an hour. It is also
flowable (and pumpable!), which allows workers to use standard
machinery such as a ready mix truck without any problems. In fact,
Cor-Tuf UHPC can be used with all standard concrete equipment. It
can be mixed, transported, and poured the same way as traditional
concrete. Your team doesnât need to learn any new techniques or
tools, but the end product is stronger and more durable.
- Freeze/thaw resistanceâUHPC has a higher
density than traditional concrete, making it virtually impervious
to water. The material does not deteriorate when exposed to deicing
chemicals or sulfates. Studies have shown that UHPC can withstand
more than 1,000 freeze/thaw cycles, making it highly superior
to regular concrete.
There are a myriad of other benefits of UHPC over traditional
concrete, including a lower carbon footprint, low-impact design,
flexibility, impact resistance, and cost savings. We have conducted
many
tests on our own Cor-Tuf UHPC so you can see in action the
amazing benefits of this revolutionary UHPC mix. We invite you to
take a look at our gallery to get a closer look at
the work we have done.
As you plan your next construction project, itâs important to
know the distinction between concrete and cement. Itâs even more
important to be aware of the advantages to be had when you choose
ultra high performance concrete over traditional concrete. We will
continue to keep you updated on advances in UHPC, particularly in
our proprietary UHPC mix that easily outperforms conventional UHPC
mixes.
The post Concrete
vs. Cement: The Hard Facts appeared first on Cor-tuf UHPC.
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