Concrete vs Cement vs Mortar
Cement is an ingredient. Concrete is a mix of cement, water, sand and stone. Mortar is a mix of cement, sand, lime and water used to bond bricks and blocks. They are three different materials.
The short version
| Cement | Concrete | Mortar | |
|---|---|---|---|
| What it is | The binder powder | Cement + water + sand + stone | Cement + sand + lime + water |
| Coarse aggregate | No | Yes | No |
| Typical use | Ingredient only | Slabs, footings, walls, steps | Joining bricks and blocks |
| Strength role | Gives the paste its binding power | Carries compression loads | Bonds units, not a structural material alone |
| Sold as | Bags of Portland cement | Ready-mix, bagged mix | Bagged mortar mix |
The mix-up is understandable: the same word appears on bags of all three materials, and a “cement mixer” or “cement truck” is, in fact, a concrete mixer. Cement is only about 10 to 15% of the volume of concrete. The rest is aggregate and water.
What cement is
Cement is a fine powder made by heating limestone and clay to a high temperature and grinding the result. The most common type is Portland cement. When it meets water it undergoes a chemical reaction called hydration, forming a paste that sets and hardens. On its own, cement paste is brittle and shrinks too much, so it is rarely used alone.
What concrete is
Concrete is cement paste combined with sand (fine aggregate) and gravel or crushed stone (coarse aggregate). The aggregate takes up most of the volume and does much of the work. The paste coats every piece and binds them together. The result is strong in compression and is used for foundations, slabs, walls, columns and pavements. Its tensile strength is low, which is why steel reinforcement goes into it for beams, suspended slabs and heavily loaded slabs. See mix ratios for the proportions.
What mortar is
Mortar contains cement, fine sand, water and often lime, which makes it more workable and sticky. It has no coarse stone. Mortar is the bedding that holds brick, block and stone together, and it fills the joints between them. It is spread thin with a trowel, so it needs to be fine and plastic. Mortar mixes are classified into types according to strength and use, such as Type N, S and M. Mortar is not a replacement for concrete: it is weaker in bulk, shrinks more and cracks if used thick.
And what about grout and stucco?
Grout is a fluid mix that fills voids, such as the cores of reinforced block walls or the space under a base plate. It may or may not contain coarse stone. Stucco is a plaster-like cement mix applied as a wall finish. Self-leveling underlayment, sand mix and repair mortars are other products built on the same ingredients. Check the label for the recommended use and thickness.
Which one do I need?
- Pouring a slab, footing, step or post hole: concrete.
- Laying block, brick or stone: mortar.
- Filling the cores of block walls: grout, as the design specifies.
- Small repairs or a thin coating: a repair mortar or patch, as the label directs.
- Making your own concrete from scratch: Portland cement plus sand and gravel, in a known ratio.
Common mistakes
- Using mortar mix to pour a slab. It lacks the coarse aggregate and will crack.
- Calling a delivery truck a “cement truck” when ordering. Ask for ready-mix concrete.
- Mixing cement and sand alone for structural use.
- Using concrete mix for laying block. It is too stiff to make a good joint.
- Assuming a stronger bag is always better. The right product depends on use.
Types of Portland cement
| Type | Name | Use |
|---|---|---|
| I | General purpose | Most buildings, slabs and pavements |
| II | Moderate sulfate resistance | Soils or water with moderate sulfates; moderate heat |
| III | High early strength | Cold weather, fast forms removal |
| IV | Low heat | Massive pours |
| V | High sulfate resistance | Severe sulfate exposure |
Supplementary cementitious materials
Ready-mix plants often replace part of the Portland cement with fly ash, slag cement or silica fume. These materials can improve workability, reduce heat and make the concrete more durable in some environments, and they reduce the carbon footprint of the mix. They gain strength more slowly in cold weather, which is something to discuss with the plant if you are pouring in winter.
Mortar types
| Type | psi | Typical use |
|---|---|---|
| M | 2,500 | Below grade, heavy loads |
| S | 1,800 | Structural, below grade, exposed to wind |
| N | 750 | General above-grade masonry |
| O | 350 | Interior, non-load-bearing |
Pick the type from the masonry plans or the block supplier. Mortar is always mixed with the water the product label states.
Reading a bag label
Labels tell you what is in the bag. “Concrete mix” contains cement, sand and gravel and is meant for pours of 2 in or more. “Sand mix” or “topping mix” contains cement and sand and is for thin sections. “Mortar mix” contains cement, sand and lime or plasticizers and is for laying masonry. “Portland cement” is cement alone and is an ingredient. Check the yield, the water, the setting times, the strength and any limits on thickness. Products that look alike on the shelf can behave very differently.
A quick guide to choosing
- If it will carry load or be poured thicker than about 2 in, use concrete.
- If you are joining masonry units, use mortar.
- If you are filling a thin gap or topping, use sand mix or a patching product.
- If you are making your own concrete, buy Portland cement and aggregates, and see the mix calculator.
- If you are unsure, read the label, or ask at the supplier.
Why the difference matters for cost
Cement is the most expensive part of concrete per pound, and the aggregates the cheapest. A mix that uses more aggregate and less paste is cheaper and shrinks less, but it needs the right proportions to be workable. Mortar and grout contain a higher share of cement and sand so they cost more per cubic foot. Using mortar mix where concrete would do wastes money, and the result is weaker in thick sections.
Frequently asked questions
Is cement the same as concrete?
No. Cement is one ingredient of concrete. Concrete also contains water, sand and stone.
What is the difference between concrete and mortar?
Concrete has coarse aggregate and is used for structural work. Mortar has only sand and is used to bond masonry.
Can I use mortar mix for a slab?
No. It lacks the coarse aggregate that gives concrete its strength and low shrinkage.
Is a cement truck a concrete truck?
Yes. People say “cement truck” but it carries ready-mix concrete.
How much of concrete is cement?
Roughly 10 to 15% by volume.
What is Portland cement?
The most common cement, made from limestone and clay, which hardens when mixed with water.
Sources
Estimate only. Results depend on the numbers you enter, ground conditions and your supplier. For structural work consult a licensed engineer and follow local codes. Brand names such as Quikrete and Sakrete are used only to cite published product data. This site is not affiliated with any brand.