Crushed stone best uses
Every size number exists because some job demanded it. Match the stone to the work — drainage wants clean and open, structure wants fines and compaction, bedding wants small and uniform — and the material does the rest.
Contents
Match the size to the job
| Job | Best size | Typical depth |
|---|---|---|
| French drain | #57 clean | 3 in around the pipe, all sidesWrap the trench in filter fabric |
| Driveway / shed base | Crusher run | 4 in per compacted lift |
| Concrete aggregate | Washed #57 or #8 | Per mix design |
| Pipe bedding | #8 | 4–6 in under and beside pipe |
| Paver leveling bed | #10 screenings | 1 in over compacted base |
| Walkway surface | #8 or screenings | 2–3 in over base |
| Railroad ballast | #3 | 12 in+ under ties |
| Construction entrance | #2 or #3 | 6 in over geotextile |
| Dry well / infiltration bed | #3 or #57 | Per storage volume |
French drains and drainage: #57
Drainage stone has one requirement: voids that stay open for decades. Clean #57 is the industry answer — its 3/4 to 1 inch particles leave generous channels for water while sitting heavily enough not to migrate off the pipe under backfill. The build: filter fabric lining the trench, 3 inches of #57 below the perforated pipe, 3 inches beside and above it, fabric folded over the top before backfill. The fabric keeps soil fines out of the voids; the stone keeps the water moving.
Driveway and shed bases: crusher run
Bases have the opposite requirement: no voids at all. Crusher run — stone plus fines, dust through 3/4 or 1 1/2 inch — compacts to about 140 lb/ft³, spreading wheel loads so the subgrade never feels a point load. Place it in 4 inch lifts, compacting each with a plate compactor or roller before the next; a new driveway wants 8–12 inches total, a garden shed 4–6. Over soft or wet subgrade, start with a lift of #2/#3 to bridge the mud, then build crusher run on top. The full layer system is covered in the driveway base layers guide.
Concrete aggregate: #57 and #8
Coarse aggregate is 60–75% of a concrete mix by volume, and angular crushed stone is the premium choice: fractured faces give cement paste more grip than rounded gravel, improving strength for the same cement content. Standard structural mixes call for washed #57; thin slabs, pumped mixes and tight rebar spacing drop to #8 so the stone passes between bars. Concrete-grade stone must meet ASTM C33 cleanliness limits — this is the one use where you should ask the quarry for certification, not just a size number.
Use-case questions
- What is the most versatile crushed stone size?
- #57 — the 3/4 to 1 inch clean blend. It drains, it handles, it walks, it locks reasonably well, and it is the specified aggregate in most ready-mix concrete. If a yard could stock only one clean size, it would be #57, and most price lists confirm it: #57 is always there, always first.
- Can one size do the whole driveway?
- Crusher run can, in a pinch — base and surface both — because it compacts at every depth. What fails is the reverse shortcut: an all-#57 driveway never locks together and migrates under tires. The proper build is still layered: large stone over soft ground, crusher run structure, then the surface course.
- What stone goes under a concrete slab?
- A 4 inch layer of compactable base (crusher run or dense-graded aggregate) where the ground needs building up, or clean #57 where the slab needs a capillary break and drainage layer. Many specs use both: dense base for grade, 2 inches of clean stone on top. Never pour on soft or organic soil.
- Which size is best around a foundation for drainage?
- Clean #57 wrapped in filter fabric against the footing drain. It is large enough to keep voids open under backfill pressure, small enough to bed the pipe evenly. #8 works close around small-diameter pipe; crusher run and screenings are disqualified — their fines seal the very voids the drain depends on.
- What crushed stone for a muddy construction entrance?
- #2 or #3 — stone big enough not to disappear into the mud. A 6 inch lift of 2 inch stone over geotextile bridges soft ground and cleans tires. Smaller stone vanishes into the muck within a week; this is the one residential job where the big classes earn their keep.
- How deep should each application be?
- Rules of thumb: French drains need 3 inches of stone around the pipe on all sides; driveway bases 4 inches per compacted lift (8–12 inches total on new builds); pipe bedding 4–6 inches; walkway surfaces 2–3 inches; paver leveling beds 1 inch of screenings over a 4–6 inch base. When in doubt, deeper base and thinner topping beats the reverse.
Pipe bedding and paver beds: #8 and #10
Small stone shines where something rigid needs uniform support. #8 cradles pipe without the point loads big stone would impose — 4–6 inches under and beside sewer, drain and conduit runs, compacted lightly so the pipe bears evenly along its length. #10 screenings do the same for pavers: a 1 inch screeded bed over a compacted crusher run base lets each paver seat perfectly flat. Keep the screenings layer thin — at an inch it is a leveling course; at four it is a water-holding sponge.
Ballast and heavy stone: #2 and #3
The big classes solve big-load problems. Railroad ballast is the classic #3 job: a foot or more of 1–2 inch stone locks around the ties, drains instantly, and can be re-tamped for decades. Residentially, the same sizes bridge soft ground — construction entrances, first lifts over mud, culvert surrounds and erosion aprons at downspout outfalls. Their limitation is handling: nothing this size spreads by rake, walks comfortably, or sits still on a slope face smaller stone would grip.
Next reads
Sources & references
- [1]ASTM D448: Standard Classification for Sizes of Aggregate — ASTM International, 2017
- [2]ASTM C33/C33M: Standard Specification for Concrete Aggregates — ASTM International, 2018
- [3]AASHTO M 43: Sizes of Aggregate for Road and Bridge Construction — AASHTO, 2018
- [4]The Aggregates Handbook, 2nd ed. — National Stone, Sand & Gravel Association, 2013