Concrete vs. Cement: What’s the Difference?

Cement is only one ingredient in concrete. Ready-mix concrete is typically made from cement, sand, stone, and water. When these materials are combined in the right proportions, they form concrete.

Concrete can also be customized with admixtures to improve performance in different conditions. Depending on the project, a concrete mix can be adjusted to:

• set faster in cold weather

• set slower in hot weather

• become more workable without reducing strength

• improve surface durability

• help reduce shrinkage-related cracking

Because of this flexibility, ready-mix concrete can be proportioned for a wide range of applications, including footings, basements, sidewalks, driveways, slabs, and roadways.

What Makes Concrete Harden?

When cement, sand, stone, and water are mixed together, a chemical reaction called hydration begins. During hydration, the cement particles react with water and start bonding together. As this process continues, the cement paste binds the sand and stone into a hardened mass.

The amount of water in the mix plays a major role in the final strength of the concrete. In general, too much water can reduce strength and durability, while the proper water-to-cement ratio helps create a stronger, more reliable finished product.

As hydration continues, the concrete gains strength over time. That is why proper placement, finishing, and curing are all important to long-term performance.

Mix Adjustments and Special Orders

Modern ready-mix concrete can be tailored to fit specific project conditions. Different admixtures and adjustments can help make concrete easier to place and better suited for weather, reinforcement, and jobsite needs.

Cold Weather Adjustments

In colder conditions, accelerators may be added to help concrete set faster and reduce the risk of freezing before it gains enough strength. If reinforcing steel or wire mesh is being used, non-calcium chloride options may be preferred.

Hot Weather Adjustments

In hot weather, retarders may be added to slow the set time and give finishers more working time before the concrete begins to harden.

Workability Adjustments

If a project requires a higher slump or more flowable concrete, a water reducer or plasticizer can improve workability without unnecessarily weakening the mix.

Fiber Reinforcement

Fiber mesh can be added to improve surface durability and help reduce issues such as plastic shrinkage cracking.

The right mix depends on the project, the weather, and how the concrete will be placed and finished.

Why Curing and Sealing Matter

Concrete does not stop changing once it is placed and finished. It still needs time and moisture to continue hydrating and developing strength, especially near the surface.

Proper curing helps:

• improve strength development

• protect surface durability

• reduce rapid moisture loss

• support better long-term performance

Concrete can be cured by applying curing compounds or by helping the surface retain moisture during the early stages after placement.

After the concrete has had time to cure, a penetrating sealer may help protect the surface from moisture intrusion and wear. When concrete is properly cured and protected, it is much more likely to perform well over the long term.

Plastic Shrinkage Cracking

What is plastic shrinkage cracking?

Plastic shrinkage cracking happens when the surface of fresh concrete dries out too quickly while the concrete is still in a plastic, non-hardened state. These cracks are usually shallow, often appear somewhat parallel to one another, and are commonly seen on slabs.

Although plastic shrinkage cracks can be unattractive, they do not usually have the same structural significance as deeper, more serious cracking.

What causes it?

Plastic shrinkage cracking occurs when moisture evaporates from the concrete surface faster than bleed water can rise to replace it. This is more likely when conditions include:

• high temperatures

• low humidity

• wind

• fast surface drying during finishing

How to help reduce plastic shrinkage cracking

Several jobsite practices can help reduce the risk, including:

• using windbreaks or sunshades when needed

• dampening the subgrade, formwork, and reinforcement before placement

• using an evaporation retardant during finishing when conditions require it

• starting curing as soon as practical

• using synthetic fibers when appropriate

Good planning and weather awareness make a major difference.

Hot Weather Concrete

Hot weather can affect concrete placement and finishing in several ways. Higher temperatures can increase water demand, speed up slump loss, shorten set time, and raise the risk of plastic shrinkage cracking and other finishing problems.

Common hot weather issues

• faster set times

• quicker moisture loss from the surface

• increased cracking risk

• reduced workability

• lower strength potential if the concrete is not properly cured

Helpful precautions in hot weather

To improve results in hot weather:

• consider using a set retarder

• avoid pouring during the hottest part of the day when possible

• make sure enough labor and equipment are available

• keep truck access and scheduling organized to avoid delays

• start curing promptly

• use windbreaks, sunshades, fibers, or evaporation retardants when conditions call for them

Hot weather does not mean concrete cannot be placed successfully. It just means planning matters more.

Cold Weather Concrete

Cold weather can slow strength gain and create serious problems if fresh concrete freezes before it develops enough strength. In general, cold weather placement becomes a concern when average daily temperatures stay below 40 degrees for several days.

If concrete freezes while still in a plastic state, its strength and durability can be severely reduced.

Why cold weather matters

• slower set time

• slower strength development

• increased risk of freezing damage

• need for additional protection after placement

Ways to protect concrete in cold weather

Cold weather precautions may include:

• ordering concrete with heated materials when necessary

• using an accelerator to speed up set time

• using mixes with higher cement content when appropriate

• placing concrete at a lower slump when suitable

• insulating the finished concrete after placement

• using insulated blankets or other protective coverings

The colder the conditions, the more important proper planning and protection become.