Last Updated on October 20, 2026 by Umar Farooq
Concrete sand vs masonry sand for pavers comes down to one rule: concrete sand (ASTM C33) goes under the pavers, and masonry sand (ASTM C144) stays out of the bed. Concrete sand is coarse, angular and drains. Masonry sand is fine and rounded, which suits mortar and not a paver bed. The two only overlap in the joints, and even there the sources split.
Concrete sand vs masonry sand for pavers: the side-by-side
| Concrete sand | Masonry sand | |
|---|---|---|
| Spec | ASTM C33 | ASTM C144 |
| Grain | Coarse, angular, mixed sizes | Fine, rounded, small |
| Drains | Freely, if washed | Slowly, per ICPI |
| Under pavers (bedding) | Yes | No |
| In the joints | Yes, with caution | Allowed by ICPI and CMHA, with caution |
| Main use | Concrete, paver bedding | Mortar, joints |
ICPI's Tech Spec 10 says bedding sand should meet ASTM C33 and adds: "Do not use mason sand because it can be slow draining and unstable." It says the C144 sand "is often called mason sand and is used to make mortar" and "should not be used for bedding sand" (CMHA/ICPI Tech Spec 10). CMHA's guide specification says the same in nearly the same words, and also bans stone dust and limestone screenings from the bed. For the full list of what to keep out, see sand for pavers.
What C33 bedding sand looks like on a sieve
A sieve is a screen with a standard hole size, and "percent passing" is how much of a sample falls through it. Pine Hall Brick's bulletin on bedding sand lists the paver grading: 100 percent passes 3/8 inch, 95 to 100 percent passes No. 4, 80 to 100 percent No. 8, 50 to 85 percent No. 16, 25 to 60 percent No. 30, 10 to 30 percent No. 50 and 2 to 10 percent No. 100 (Pine Hall Brick).
Read it as a spread of sizes: big grains hold the bed open, middle grains fill the gaps and very little is dust. The bulletin also asks for washed sand with under 3 percent passing the No. 200 sieve, and often under 1 percent for heavy traffic. That is the number to ask the yard for. "Concrete sand" on a delivery ticket is not the same as a sieve analysis.
Why masonry sand fails under pavers
The bed and full joints create friction between pavers, and that friction is the interlock. Pine Hall says angular or coarse sand works best at it, while round-particle sand like mason sand reduces friction and leads to sand loss. Its small, rounded grains also "will settle differently across the pavement causing an uneven surface and potential drainage problems." Add water and a saturated bed can turn into what the researchers it cites call a "lubricating slurry." Washed sand with few fines drains instead.
Masonry sand feels like flour with ambitions. Concrete sand feels gritty, and gritty is the point.
Masonry sand in the joints: allowed, with a catch
Tech Spec 10 says bedding sand may be used as joint sand, and that dry sand meeting C144 may be used too. CMHA's guide specification allows C144 in the joints, and also C33. So masonry sand is not banned from the patio, only from under it. Pine Hall explains the catch from both sides:
- C33 in a joint compacts better, but some grains are too big for a 1/8 inch joint and wedge at the top, so the installer sweeps again and removes the oversize pieces.
- C144 in a joint fills easily, but "the easier a sand goes into the joints the easier it will come out." Joint sand loss is the most common cause of vehicular pavement failures in the bulletin, which advises against finer joint sands there.
For a patio, either works if you keep the joints full. If you want something that holds, polymeric sand beats choosing between them, and polymeric sand alternatives compares the options.
When the sources disagree
Groupe Bellemare's supplier guide puts concrete sand against masonry sand in a table. Concrete sand is for concrete pavers and driveways, with drainage and interlock as the benefit. Masonry sand is for brick and natural stone pavers, with a smooth finish, easy leveling and "superior compaction." It never says which layer each goes in, but a reader could easily take masonry sand for the bed. Hunker's short guide goes the other way: masonry sand and stone dust are too fine for a stable base.
The standards bodies (ICPI, CMHA) and Pine Hall say no for bedding. I side with them because they give a mechanism, which is grain shape, drainage and settlement, plus a spec number to ask for. A supplier table gives a feeling. One more difference: ICPI Tech Spec 10 allows a 1 to 1 1/2 inch screed, while CMHA and ICPI Tech Spec 2 say a nominal 1 inch. I follow the 1 inch, and screeding sand for pavers covers why.
At the yard: ask for C33, and buy one sand
The cheaper option comes first. You do not need two sands, because Tech Spec 10 says bedding sand may be used as joint sand. One washed C33 concrete sand covers both layers, and you sweep a little longer to clear the oversize grains.
- Ask for washed concrete sand meeting ASTM C33, and whether they have a sieve analysis.
- Prefer silica sand. Pine Hall says silica sands are generally harder, and that limestone-based screenings can cause efflorescence.
- Do not accept a substitute because the yard is out. Wait a day.
Coarse under the pavers, fine only if it has to be
Use washed C33 concrete sand for the 1 inch bed, and keep masonry sand to mortar and, where your spec allows, the joints. The pavers get the credit. The grain shape does the work nobody sees.
FAQ
Can you use masonry sand under pavers?
No. ICPI's Tech Spec 10 says not to use mason sand for bedding because it can be slow draining and unstable, and Pine Hall says its small, rounded grains settle unevenly. Use washed ASTM C33 concrete sand.
Is concrete sand the same as paver sand?
Not always. Bags sold as paver sand can be bedding or joint sand, so read the back. Bedding sand should meet ASTM C33. Joint sand may be C33 or C144, or a polymeric product.
Can you use masonry sand for paver joints?
Often yes. ICPI and CMHA allow ASTM C144 sand in joints. Pine Hall warns that finer sand goes in easily and also comes out easily, so avoid it on vehicular pavements and keep the joints full.
Can I mix concrete sand and masonry sand?
I found no spec that allows blending, and mixing changes the grading that the C33 numbers describe. Use one sand that meets the spec for each layer.
