Cement is an ingredient, not a product. Portland cement is a fine grey powder that acts as the binder. On its own it is brittle, shrinks badly and is not used for anything structural.
Everything else on this page is cement plus other things.
The three recipes
| Contains | Coarse aggregate | Typical strength | For | |
|---|---|---|---|---|
| Concrete | cement + sand + gravel + water | yes | 3,000–4,000 psi | slabs, footings, posts |
| Mortar | cement + sand + lime + water | no | 750–2,500 psi | bonding brick and block |
| Grout | cement + sand + water, high flow | no | varies | filling voids and cores |
The presence or absence of gravel is the main structural difference. Coarse aggregate is most of concrete's volume and most of its strength — the cement paste binds stones together and the stones carry the load.
Mortar leaves the gravel out on purpose. It exists to be spread in a thin, sticky, workable layer between masonry units, and gravel would make that impossible. Lime is added for workability and for the slight flexibility that lets a wall move without cracking every joint.
Grout is formulated to flow into places nothing can be pushed into — the hollow cores of block walls, around rebar, under base plates.
Two substitutions that actually fail
Mortar used for a structural pour. It has no coarse aggregate, so it is weaker, shrinks more, and costs several times as much per cubic foot. Setting a fence post in mortar rather than concrete produces a post that loosens. This mistake usually starts at the store, from bags that look similar.
Concrete used to lay block or brick. The gravel prevents a thin even bed, joints end up inconsistent, and without lime the mix is harsh to work and unforgiving. The wall will be visibly bad before it is structurally bad.
Neither substitution is subtle once it has happened. Both are easy to avoid at the point of purchase — read past the brand name to what the bag says it is for.
Mortar types
Mortar comes in graded types, and stronger is not better here either. Mortar should be weaker than the units it bonds, so that movement cracks the joint rather than the brick — a cracked joint is repointed, a cracked brick is replaced.
- Type N — the general-purpose choice for above-grade walls.
- Type S — higher strength, for below-grade and load-bearing work.
- Type M — highest strength, for foundations and retaining walls.
Using Type M everywhere "to be safe" transfers cracking from the joints into the masonry.
Specialist concretes
- Fast-setting — sets in 20–40 minutes. Made for fence posts, where it can be poured dry into the hole with water added after. Not for slabs: there is no time to finish the surface.
- High-strength — 5,000 psi and up, for structural work. See what PSI you need before reaching for it.
- Sand mix / topping mix — no coarse aggregate, for thin repairs under about 2 inches where regular concrete cannot be placed thin enough.
- Countertop mix — fine aggregate, additives for finish quality.
Choosing in one line
Pouring something thick that carries load: concrete. Sticking masonry units together: mortar. Filling a void or a core: grout. Buying cement on its own: only if you are batching from raw materials and know the ratio you want — see the 1:2:3 mix.
FAQ
What is the difference between cement and concrete?
Cement is the powdered binder. Concrete is cement mixed with sand, gravel and water. Cement alone is not used structurally.
Can I use mortar instead of concrete?
No. Mortar has no coarse aggregate, so it is much weaker, shrinks more and costs more per volume. It is for bonding masonry, not for pouring.
Can I use concrete to lay bricks?
Poorly. The gravel prevents a thin even bed and the mix lacks lime, making it harsh to work. Use mortar.
What is grout used for?
Filling voids — the hollow cores of block walls, around reinforcement, under base plates. It is formulated to flow rather than to be spread.
Which mortar type should I use?
Type N for general above-grade work, Type S below grade or load-bearing, Type M for foundations. Mortar should be weaker than the units it bonds so cracks land in the joints.