Grout vs. Concrete Explained

You’ve probably heard of grout and concrete before, but unless you’re a professional mason, you likely don’t know all the minute differences when it comes to grout vs concrete. Terms like cement, mortar, concrete, and grout are often used interchangeably, although there are actually major differences between the strength and application of these materials.

Both grout and concrete are cement-based substances that are commonly used in DIY and construction projects. They’re both commonly sold as powders which are then combined with a precise amount of water to create a paste before application. Additionally, both substances are designed to dry and cure into a final hardened product.

Let’s take a closer look at grout vs concrete, and examine the differences between these two building materials.

Grout

While grout is often confused or mistaken with mortar, their actually some subtle differences between the two. Mortar is a general term for the glue-like material which is used to hold together bricks, stone, and other masonry materials. It consists of cement, fine sand, and lime.

Grout is a type of mortar but is formulated without the lime additive. Lime is added to mixes to add durability as well as pliability, so the lack of lime makes grout more of a gap filler and sealer than a primary glue for connecting pieces of masonry. It’s commonly used to fill in the gaps when laying down ceramic tile and is also used in heavy construction for connecting sections of precast concrete.

grout closeup
Grout between ceramic tile. [Source]
Unlike mortar, grout is thin and viscous and will flow in and fill up gaps between tiles. This makes it ideal for sealing off tiles in showers and bathroom floors. Grout is also one of the few structural pastes that’s designed to form a watertight seal once cured, which is another reason you’ll find it used in bathroom and kitchen construction.

Grout comes sold either as a powdered or pre-mixed form and comes in a wide variety of colors and applicators. There are also several different varieties of grout, which are used for slightly different applications.

Types of Grout

  • Unsanded grout: This type of grout is used for tiles with gaps of less than 1/8”. It’s thinner than standard grout, making it easier to work in between narrow joints. The lack of sand also makes it stickier than standard grout, so it’s useful for tiling vertical surfaces like shower stalls.
  • Finely sanded grout: Sanded grout is used for tiling joints between 1/8” and 3/8” thick. It contains fine sand and is a good general use grout for a variety of tiling projects. It’s inexpensive, forms a sturdy joint, and is fairly easy to work with.
  • Quarry-type grout: This grout contains coarser sand than the previous type, and is appropriate for use in larger joints up to ½” wide.
  • Epoxy grout: This is a specialty grout that consists of a resin and a hardener. It’s highly resistant to moisture and stains and has exceptional bonding capabilities. It’s used in particularly wide gaps, and for tile in areas susceptible to stains.

Concrete

Concrete is a versatile building material made from a combination of cement, sand, and a coarse aggregate like gravel. It’s used in a wide variety of projects, from building foundations to laying down sidewalks to setting fence posts.

Like grout, it often comes in a dry powder form, which is then mixed together with water to create a semi-liquid paste-like material. Concrete can be formed into nearly any shape using molds and forms, and then when it dries it transforms into the rock-hard material we are all familiar with. It’s is often used in conjunction with metal reinforcement like rebar, which adds durability and strength to the completed material.

Types of Concrete

Concrete comes in a variety of dry mixes, with some of the most commonly used types being a fast-setting concrete mix, high-strength mix, and all-purpose concrete. For smaller household DIY projects, buying bags of premixed concrete and then adding water and mixing it in a wheelbarrow yourself makes sense.

For larger projects like pouring a slab or constructing a foundation for a building, you can order concrete from a supplier delivered directly to your job site in a barrel truck. This type of concrete is called ready-mix concrete.

concrete mixer pouring into wheelbarrow
Concrete mixer pouring into a wheelbarrow. [Source]
If you want to save money or try your hand at doing it yourself, you can also mix your own concrete. All you need for this is 1 part sand, 1 part Portland cement, 1 ½ parts gravel, and ½ part water. Portland cement is the most commonly used cement type used in concrete and is also used in many types of grout.

Both grout and concrete contain cement as one of the main ingredients, which means you’ll want to avoid getting it on your bare skin. Cement is caustic, which means it can burn and irritate the skin if you come in contact with it.

Grout vs Concrete Comparison

Applications

Both grout and concrete are used as construction materials, but their functions are quite different.

Grout is typically used for filling in gaps in ceramic tiles when building bathrooms and kitchens. It’s generally more workable and vicious than concrete, as it needs to fill in tiny gaps between tiles as small as 1/8” wide.

Concrete has many uses and applications and is a versatile and cost-effective construction material. Common uses for concrete in DIY projects are setting fenceposts and mailboxes, pouring slabs for garages or sheds, and pouring sidewalks or curbs.

Strength

When it comes to the strength of construction materials, there is a lot to consider. There’s compressive strength, which is the strength of a material to withstand pressure. There’s tensile strength, which is the ability of a material to resist breaking while under tension of being pulled apart. And lastly, we have flexural strength, which refers to the strength of a material to resist breaking when bent.

Compressive Strength

For concrete and grout, the most important strength measurement is compressive strength. Both tensile and flexural strength are relatively difficult to measure reliably, which is why compressive strength is relied on when describing the strength of a material.

Compressive is measured in pounds per square inch (PSI). Generally, the higher the PSI, the more expensive the product is.

Concrete strength varies depending on its intended use but generally falls somewhere between 3,500 and 8,000 PSI. General-purpose concrete commonly achieves 4000 PSI when fully cured, which can take up to 28 days to reach. High strength concrete commonly cures to 6000 PSI, which is enough for projects that need to withstand heavy impact and wear and tear.

Grout strength can also vary widely, depending on its intended usage. Grout used in tiling commonly features somewhere between 2,500 and 5,000 PSI, while high-strength grout for use with pre-cast concrete and steel columns can reach 12500 PSI.


Hopefully, you now have a better idea of the differences when it comes to grout vs concrete. These two materials may seem similar in many ways, but there are actually quite a few key differences between the two.

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