CA-6 Gravel: What It Is and When to Schedule Delivery

CA-6 gravel is a crushed limestone aggregate that follows an IDOT (Illinois Department of Transportation) gradation specification used throughout the construction and paving industries across Southern Illinois. The “CA” stands for Coarse Aggregate, and the “6” identifies the specific gradation, which describes the mix of particle sizes that make up the material. Unlike coarser single-size stone, CA-6 rock contains particles ranging from roughly one inch down to fine limestone dust, and that blend is exactly what gives it its compaction properties. When spread and compacted, those fines fill in the gaps between larger pieces to form a dense, interlocked base that holds weight and resists movement. For any paving, slab, or surface project that requires a stable foundation underneath, CA-6 gravel is typically the first material called out on the spec.

What Makes CA-6 Gravel Different

CA-6 gravel compacts into a load-bearing base in a way that coarser, cleaner stone cannot match, and the difference comes down to the fines content. When the material is placed and compacted, the smaller particles pack into the voids between the larger ones and create a structure that resists shifting and settling under load. That behavior is why it gets specified by name on project plans rather than left as a general contractor preference. Surfaces placed over a weak or improperly compacted base will show it early through cracking, heaving, and premature failure. A properly compacted CA-6 rock layer is what protects the investment in whatever finish surface goes on top of it.

CA-6 vs. CA-6 Recycled

CA-6 Recycled is processed from crushed concrete or recycled asphalt and graded to meet the same particle size specification as standard CA-6 aggregate. It compacts similarly to virgin material and performs well in most base and backfill applications where the project does not require new limestone. Many contractors use it for utility trench backfill, non-structural fill, and base prep work where budget matters and the spec allows flexibility on material source. When a project specifically calls for IDOT-approved virgin aggregate, standard CA-6 is the right call. When the spec allows recycled material, CA-6 Recycled is worth pricing before finalizing the order.

Where CA-6 Rock Gets Used

CA-6 rock is ordered across a wide range of residential and commercial applications, and knowing the common uses helps confirm the right material is going on the right job. The combination of gradation and compactability makes it the standard base material wherever load-bearing capacity is the goal, not drainage. It is specified regularly across transportation, construction, and site development work throughout the region. Common applications include:

Driveway base: Residential and commercial driveways typically call for 4 to 6 inches of compacted CA-6 gravel beneath any paved or gravel surface
Parking lot subbase: CA-6 is placed and compacted before asphalt or concrete is laid on commercial parking projects
Utility trench backfill: The material compacts well in trenches and provides stable support for the surface above
Slab and pad prep: Garages, building pads, and slab-on-grade foundations regularly specify CA-6 rock as the base layer
Site prep and grading: Rough grading ahead of paving often calls for CA-6 gravel as the working surface before the finish grade goes in

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How Much CA-6 Do You Need

Calculating the right quantity before calling for delivery keeps the project moving and avoids waiting on a second load mid-project. The volume of CA-6 gravel required depends on the square footage of the area and the specified base depth, which are typically known before the delivery call is placed. Multiplying length by width by depth (in feet) and dividing by 27 converts the cubic footage to cubic yards, and bulk crushed limestone delivery is ordered and priced by the ton. The volume calculator on this site handles the conversion automatically. Plugging in the job dimensions before calling gives the team a clear quantity to work from and helps keep the schedule on track.

When to Call for CA-6 Delivery

Lead time for CA-6 delivery depends on load size and how tight the project schedule runs, and calling ahead is always the right move. Residential orders are usually straightforward, but large commercial loads or multi-truck deliveries benefit from scheduling ahead to align truck arrival with site readiness. Any job where a concrete pour or paving crew is waiting on the base layer is not the job to line up at the last minute, since delays in base delivery push back every phase that follows. Scheduling driveway gravel delivery or larger commercial orders a day in advance gives time to spread and compact the material before the next phase starts. Check the rock delivery page for the full list of materials available for delivery, and use the locations page to find the plant closest to your job.

Frequently Asked Questions About CA-6 Gravel

What is CA-6 gravel?

CA-6 gravel is a crushed limestone aggregate graded to an IDOT specification that includes a range of particle sizes from roughly one inch down to fine limestone dust. That blend of sizes allows it to compact into a dense, stable base used under driveways, parking lots, slabs, and other paved surfaces.

What is CA-6 gravel used for?

CA-6 rock is primarily used as a compacted base or subbase layer under pavement, concrete slabs, and other hard surfaces. Common applications include residential driveways, commercial parking lots, utility trench backfill, and slab prep for garages and building pads.

How deep should CA-6 be under a driveway?

Most residential driveways call for 4 to 6 inches of compacted CA-6 gravel as the base layer. Heavier traffic areas or commercial applications may require deeper base depths depending on soil conditions and load requirements.

What is the difference between CA-6 and 1″ clean stone?

CA-6 gravel includes fines that allow it to compact into a tight, load-bearing base. One-inch clean stone has little to no fines, which means it does not compact the same way but provides significantly better drainage. The right choice depends on whether the job needs a compactable base or open drainage.

What is CA-6 Recycled?

CA-6 Recycled is crushed concrete or recycled asphalt processed to match the gradation of standard CA-6 aggregate. It performs comparably to virgin limestone in most base and backfill applications and is typically more economical when the project spec allows for recycled material.

Can CA-6 gravel be used as a finished driveway surface?

Yes, compacted CA-6 rock works well as a finished surface on unpaved residential and rural driveways. It compacts firmly under regular vehicle traffic and holds up over time when properly installed.

How is CA-6 gravel ordered and delivered?

CA-6 gravel is sold and delivered by the ton. Estimating cubic yardage using a volume calculator before placing the order helps determine the right tonnage to request and prevents delays from running short on material mid-project.

Ready to order crushed limestone delivery for your next project? Contact Beelman Ready Mix or Concrete Supply of Illinois to get your CA-6 gravel order scheduled.

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CA-6 Gravel: What It Is and When to Schedule Delivery

What Makes CA-6 Gravel Different

CA-6 vs. CA-6 Recycled

Where CA-6 Rock Gets Used

How Much CA-6 Do You Need

When to Call for CA-6 Delivery

Frequently Asked Questions About CA-6 Gravel

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