CA6, #53 and #73 are related dense-graded aggregate names, not guaranteed substitutes. Midwest suppliers associate them with base and driveway products containing smaller particles and fines. CA7 is commonly sold as clean stone for drainage. Order by the actual product, gradation and layer requirements, not the nickname alone.1, 2, 3 CA6 can be limestone, gravel or recycled concrete; it does not always mean limestone.1
Stone names: what the sources actually say
| Name | Source-grounded description | Ordering caution |
|---|---|---|
| CA6 | Ozinga lists road rock, Grade 8, Grade 9, Indiana 53 and dense-grade names; it sells limestone and recycled-concrete versions.1 | Confirm material source and certification, not just CA6. |
| #53 | Ozinga calls Indiana #53 the regional equivalent of CA6; INDOT lists #53 separately in its dense-graded chart.1, 3 | A supplier cross-reference is not proof of identical specifications. |
| #73 | INDOT lists a separate dense-graded #73 column. Gravelshop sells a product called 3/4-inch minus limestone.3, 4 | Use the governing specification; seller figures may differ. |
| CA7 | Columbia Quarry describes about 1-inch clean limestone; Ozinga groups CA7 with CA11 and Indiana 57 under its 3/4-inch bedding-stone listing.2, 5 | Even supplier size descriptions differ. Ask for the actual sieve data. |
| CA11 | Columbia Quarry describes 3/4-inch clean limestone for bedding and trench work.2 | Confirm pipe or drain-system requirements. |
| CA10 | Columbia Quarry describes 3/8-inch limestone chips for finish and other uses.2 | A finish-layer suggestion is not a universal driveway design. |
“Minus” and “clean” are useful supplier descriptions, but neither label certifies a project. A product name alone does not establish stone quality, full gradation, fines properties, installed strength or drainage performance.
CA6 vs #53 vs #73: compare gradation, not a single size
The table below gives percent passing by sieve. The CA6 column is Ozinga’s published product table; #53 and #73 are INDOT’s 2026 aggregate specification chart. These are different sources and standards, not three identical products.1, 3
| Sieve | CA6: Ozinga | #53: INDOT 2026 | #73: INDOT 2026 |
|---|---|---|---|
| 1-1/2 in | 100 | 100 | Not listed |
| 1 in | 90-100 | 80-100 | 100 |
| 3/4 in | Not listed | 70-90 | 90-100 |
| 1/2 in | 60-90 | 55-80 | 60-90 |
| No. 4 | 30-56 | 35-60 | 35-60 |
| No. 30 | Not listed | 12-30 | 12-30 |
“Not listed” means that this cited table does not give a value at that sieve, not zero passing. A descriptive “3/4-inch minus” name also does not mean every particle must be below 3/4 inch: INDOT’s #73 column allows 90-100% passing that sieve while requiring 100% through the 1-inch sieve.3
A seller chart is not the official #73 specification
Gravelshop says its #73 product meets a gradation of 40-70% passing No. 4 and 0-10% passing No. 200. INDOT’s 2026 chart lists 35-60% and 5-12%, respectively, for #73.3, 4 Those ranges overlap but are not the same. This does not establish that a particular delivery fails; it means the website description alone is not enough to certify compliance. Request current test results against the specification your project actually uses.
Which stone belongs in a driveway layer?
- Base or compacted aggregate: Ozinga lists CA6 for driveways and road base. INDOT section 301 treats aggregate base as a placed, compacted course on prepared grade.1, 6
- Exposed driving surface: do not assume every base product is the right surface mix. In INDOT section 303, #53 is listed for aggregate pavement/shoulders, while #73 is restricted to surface courses when specified.6 This is Indiana contract context, not a thickness prescription for every private driveway.
- Drainage layer: Columbia Quarry identifies CA7 and CA11 as clean drainage products. Gravelshop warns against its fines-bearing #73 in drainage-critical French drains and some septic applications.2, 4 Match the whole system, including outlet, filter and pipe requirements.
- Layered finish: Columbia Quarry suggests CA6 base with CA10 or chips above; Brohez, an Illinois hauler, recommends CA6 or road pack for driving.2, 7 These are supplier recommendations, not interchangeable engineered designs.
Brohez describes CA7 as not packing into the same hard fines-bound surface as CA6.7 Do not turn that description into “clean stone cannot be compacted” for every use. Clean stone and dense-graded material serve different layer requirements. Drainage, ground condition, loading and placement still need a site-specific plan.
Recycled CA6 is not automatically the same as limestone
Ozinga says its recycled CA6 is crushed concrete and 15% lighter than limestone CA6. It separately notes that Grade 8 recycled meets the same gradation as its CA6 but is not submitted for DOT certification.1 Keep that weight claim tied to this supplier, not every recycled aggregate. INDOT section 301 also excludes processed recycled-concrete No. 53 from aggregate base when an underdrain is specified.6 That is a concrete example of why a matching size name does not approve a substitution everywhere.
How much to order: separate geometry from delivery
Cubic feet = length (ft) × width (ft) × selected depth (in) ÷ 12.
Cubic yards = cubic feet ÷ 27.
US short tons = loose cubic yards × matching lb per loose yard ÷ 2,000. Use a supplier-confirmed loose-to-finished conversion when the measured depth is compacted thickness. Keep any separate handling allowance and actual sales increment distinct. This guide does not add a generic 10% for settling.
Gravelshop’s page gives 1.2 tons per yard in its density summary and 1.3-1.5 in the body text.4 That contradiction remains unresolved; do not average the values or use them as a verified order conversion. Ask for the delivered product’s factor, moisture/volume basis and ton unit.
Three checked examples
1. A 12 × 40-foot layer
At a selected 4-inch finished thickness, geometry is 160 cu ft = 5.925926 finished cu yd. If the project has a hypothetical verified requirement of 1.15 loose yards per finished yard, the loose target is 6.814815 cu yd. A supplier selling half-yard increments would round that to 7 loose cu yd. At a hypothetical matching 2,800 lb per loose yard, that rounded order weighs 19,600 lb = 9.8 US short tons. These are example inputs, not a CA6 density or recommended depth.
2. Compare equal loose volumes
For an explicitly selected 6 loose cu yd, hypothetical limestone at 2,800 lb per loose yard weighs 16,800 lb = 8.4 short tons. If a verified recycled product on the same basis is exactly 15% lighter, its factor is 2,380 lb per loose yard and its mass is 14,280 lb = 7.14 short tons. Equal loose volume does not prove equal finished coverage, drainage or structural performance. This illustrates the arithmetic, not an order using Ozinga’s claim without a quote.
3. A pad with a defined volume reduction
A selected 10 × 20-foot area at 6-inch finished thickness contains 100 cu ft = 3.703704 finished cu yd. Suppose a hypothetical material retains 80% of its loose volume at the required installed condition. Loose target = (100 ÷ 27) ÷ 0.80 = 4.629630 cu yd. At quarter-yard sales increments, round up to 4.75 loose cu yd. Adding 20% instead gives only 4.444444, which is a different relationship. No generic pad design or handling reserve is implied.
Before ordering
- Confirm the layer purpose and governing requirements, including whether substitutions are allowed.
- Request exact source material, current sieve analysis and any needed quality/certification documentation.
- Confirm finished thickness separately from loose delivery volume; define the conversion instead of guessing a settling percentage.
- Confirm the unit sold, matching weight factor, sales increments, minimum delivery, taxes and haul charges. A smaller example volume is not a promise of supplier delivery availability.
- Have the carrier verify payload, access and unload location. A truck type name does not establish a safe or legal load.
FAQ
Is CA6 the same as #53?
Ozinga uses Indiana #53 as a regional equivalent of CA6.1 That helps identify a product family, not prove that every quarry product meets the same current specification. The published tables above differ.
Is #73 just smaller CA6?
Do not reduce the comparison to nominal size. Different sieve ranges and application requirements matter; INDOT gives #73 its own dense-graded column and section 303 surface-course limitation.3, 6
Can CA7 replace a fines-bearing driving layer?
Not simply because its nominal size looks similar. Suppliers describe CA7 as clean drainage stone, while CA6 is associated with packing/base uses.2, 7 Choose the material for the required layer.
Does a 15% lighter recycled product mean 15% less volume?
No. Lower weight per matching unit volume changes mass, not automatically the volume you need. Confirm the actual delivered and installed relationships.
Related tools and guides
Gravel calculator | #57, #67 and #8 size chart | Driveway quantities | Yards and US short tons converter
Sources
- Ozinga: CA6 Base Stone (supplier names, gradation, material variants and weight claim)
- Columbia Quarry: Crushed Limestone Grades (supplier descriptions and layer suggestions)
- INDOT: 2026 Aggregate Specifications chart (official sieve ranges; chart dated March 2, 2026)
- Gravelshop: #73 Crushed Limestone (seller description and conflicting density/gradation figures)
- Ozinga: Limestone (supplier clean-stone grouping)
- INDOT: 2026 Standard Specifications, Division 300 (sections 301 and 303; Indiana contract context)
- Brohez Trucking: CA6 vs CA7 (Illinois hauler recommendations, June 2026)