Cement vs. Concrete

Do you work on a construction site or DIY projects? You’ve likely come across these composite materials. Cement and concrete are vital to modern construction, from houses and sidewalks to skyscrapers and dams. 

When it comes to cement vs. concrete, what’s the difference? Let’s find out!

Cement is the Binding Element 

Cement or hydraulic cement is a gray powder that creates a stone-like bond after mixing with water. We’ll discuss the ingredients in a moment. Cement is not a complete building material because it requires additional materials, known as aggregates, to make it durable. Aggregates include sand and crushed stone. 

Mixing cement with water causes a chemical reaction that transforms the liquid mix into a rock-solid substance. It continues to harden over days or weeks, depending on the ratios of specific ingredients in the mixture.

What is Portland Cement?

You may see bags of cement labeled as “Portland Cement.” Joseph Aspdin of Leeds, England, developed the first modern cement process in the 1800s. He called it Portland because the color reminded him of the stone quarries on the Island of Portland on the British coast. Manufacturers still use Portland or cement interchangeably, and up to 98% of the cement used in construction is Portland.

Cement consists of eight main ingredients. Here is the list and their approximate proportions:

Ingredient	Percentage in Cement
Lime (Calcium oxide or Calcium hydroxide)	60 – 65%
Silica (Sand or Silica dioxide)	17 – 25%
Alumina (Aluminum oxide)	3 – 8%
Magnesia (Magnesium Oxide)	1 – 3%
Iron Oxide	0.5 – 6%
Calcium Sulfate	0.1 – 0.5%
Sulfur Trioxide	1 – 3%
Alkaline	0 – 1%

 

Like a mineral cake mix, varying the amounts of each ingredient affects the cement’s final strength and curing time. 

Creating cement requires many chemical reactions between the various ingredients during the four-step manufacturing process. 

Step 1 – Grinding, proportioning, and blending of the ingredients.

Step 2 – Pre-heating the mix to remove moisture.

Step 3 – The mix enters a kiln and heats up to 2750°F (1510°C) to produce “clinker,” hardened, marble-sized balls of cement.

Step 4 – The clinker goes through rapid cooling and then ground to a fine powder we know as cement.

Depending on the exact mixture, there are five types.

5 Types of Cement 

ASTM (The American Society for Testing & Materials) lists the types of cement and their uses:

Type 1 – Normal Cement – General purpose cement for pavement, reinforced concrete buildings, concrete sidewalks, bridges, and sewers. Type 1 reaches design strength in 28 days.

Type 2 – Moderate Sulfur Resistance – Used where sulfates can be an issue, such as drainage structures that contact water containing moderate sulfate concentrations.

Type 3 – Very Early Strength Cement – Similar to Type I, except the particles are smaller. It’s the best choice for cold weather pouring because it sets fast and provides high strength in a week or less.

Type 4 – Low Heat Cement – Used for mass concreting such as dams because it produces less heat. Reaches design strength in 90 days.

Type 5 – High sulfate Resistance Cement – Used where the concrete contacts highly alkaline soil or groundwater.

Various types of concrete have different setting or curing times. Most concrete reaches 90% or more of its full strength within 28 days. To learn more about curing times, go to our blog, “How Long Does Concrete Take to Set?”

Concrete Is The Complete Building Material

Concrete combines cement, clean water, sand, and gravel. The cement reacts with the water to bind everything together, forming a solid structure.

Two primary factors contribute to concrete’s strength, the additional materials and the water to cement ratio. Aggregate in concrete is usually sand and coarse crushed stone because the sharp edges, clean surfaces, and rough texture form the strongest bond with the cement. Aggregates comprise 60 to 75% of concrete’s volume.

The ratio of water in the mix is a critical factor. A mixture of 0.4% water will create stiff concrete with a strength up to 5,600 psi. Concrete made with 0.8% water is thin, wet, and weak at only 2,000 psi. 

The ratio of sand and stone in the mix also adds strength. Here is a typical concrete mixing ratio chart comparing strengths at various ratios.  

Compressive Strength	Mixing Ratio Cement: sand: stone	General Uses
2500 psi.	1:2:4	Small slabs. Fence posts
3000 psi	1:3:3	Slabs, floors, walls, footings
3500 psi	1:2.5:3	Patios, walkways, slabs
4000 psi	1:2:3	Driveways, exterior slabs
4500 psi	1:2:2	Commercial floors and slabs

[Courtesy of Everything-about-concrete.com]

People refer to concrete and cement interchangeably, but they are not the same. 

The Difference Between Cement and Concrete

The primary difference between concrete and cement is that cement is the binding agent for making concrete. Cement alone is too brittle and weak for most purposes which is why builders use concrete. 

Following are the pros and cons of concrete.  

Pros of Using Concrete

• Durable and long-lasting 
• Water-resistant
• A versatile building material
• Easy to add to existing structures

Cons of Using Concrete

• Heavier than most building materials
• Relatively expensive to make 
• Not biodegradable
• Difficult to recycle

Besides concrete, cement is a primary ingredient of another common building product used at the construction site, mortar.

Is Mortar Different Than Cement or Concrete?

Mortar is the glue that keeps bricks together in brick walls but is not strong enough to use as a stand-alone building material like concrete. It’s a mix of Portland cement, sand, and lime. Mortar has higher water, sand, and lime content than concrete to make it more pliable so masons can form it easily between bricks or concrete blocks.

Let’s get back to concrete and cement. You probably have some questions.

Fundamental Questions About Concrete and Cement

We have selected a few FAQs for your reference. 

Can you pour concrete in cold weather?

Cementing in cold weather is possible if you insulate the concrete and allow it to cure without freezing. During the hardening process, called curing, concrete creates heat. If conditions cool the concrete too fast, it won’t cure properly. Ideal pouring conditions are between 50 to 60 °F (10 to 15.5°C). Temperatures below that can drastically reduce the setting times and strength of concrete. 

The best solution is to use concrete blankets that insulate, protect from rain or snow, and add heat for optimal concrete curing during cold or freezing weather.

Which is better, cement or concrete?

“Better” is subjective. Concrete is stronger when cured but stiff and hard to work. Cement is more fluid and can work into molds or decorative shapes for architectural features or pottery.

Is cement stronger than concrete?

No, concrete is stronger due to the addition of aggregates. A pressure test measures the tensile strength of hardened concrete. Depending on the type of cement and the water to cement ratio, concrete can withstand pressures from 3,500 to 5,000 psi. Portland cement alone is too weak and brittle.

Why do people say cement instead of concrete?

The term cement has been around since the 1800s. People not in the construction business often use the generic term cement when describing any hardened material containing cement, such as a floor or slab.

What is the difference between dry and wet cast concrete?

Wet cast concrete is the liquid form of concrete we see pouring from a cement mixer, hopper, or truck. It flows evenly over rebar reinforcing bars to make floors or walls in large buildings. It can take days to cure and dry.

The dry cast uses very little water in the concrete mix. It has a hard clay-like texture that dries in about an hour. Dry cast concrete is essential to manufacturing box culverts, concrete pipes, and other pre-formed materials.

Which is Better, Cement or Concrete? 

When it comes to cement vs. concrete, concrete is the material used in construction all over the globe. It has high tensile strength and can pour into any shape. However, there is no concrete without cement. 

Cement alone cannot support much weight without breaking. To learn more, read Powerblanket’s blog, “Construction Solutions.” 

Powerblanket has a full line of heated concrete curing blankets if you need to work with concrete in cold weather or winter.