Crushed Limestone

Crushed limestone starts as quarried rock, then gets run through crushers and screens to sort it into numbered grades. This is the key difference from river gravel, which is naturally rounded by water and simply sorted by size. Limestone's crushing process leaves every fragment angular, with sharp broken faces that grip against neighboring pieces instead of rolling past them. The numbered grading system reflects both particle size and how much fine material, essentially rock dust, remains mixed in. Clean or washed grades like #57 have that dust screened out, leaving mostly uniform stone with large void space for drainage. Dense-graded grades like #304 or #411 keep the fines in place, and those fines are what let the material compact into a nearly solid mass under a roller or plate compactor. Knowing which category you're buying, clean versus dense-graded, matters more with limestone than with most other aggregates, because using the wrong one undermines either drainage or compaction depending on the job.

A good limestone base starts with excavation to the proper depth, accounting for both the stone layer and any topping material like pavers or gravel. Limestone should go down in lifts of 2 to 3 inches at a time, with each lift compacted before adding the next. Skipping this step and dumping the full depth at once is the most common cause of later rutting and settling, because the middle and bottom of a thick pour never get properly densified. A plate compactor works for walkways and small patios, while driveways and larger areas typically need a vibratory roller. Check slope as you go, aiming for at least a slight grade away from structures so water sheets off rather than sitting on the base. Once compacted, dense-graded limestone forms a surface firm enough to walk or drive on directly, though most driveway and patio installations add a finer topping layer for a smoother finish and better appearance.

Compared with crushed granite / decomposed granite. Granite is harder and more weather resistant than limestone's softer sedimentary rock, so it holds up better under constant traffic and heavy freeze-thaw cycles. Crushed limestone costs less and runs lighter in tone, but it is more chemically reactive in acidic soil or water, where granite stays essentially inert.

Compared with pea gravel. Pea gravel is rounded and rolls underfoot instead of locking together, so it makes a poor compacted base. Crushed limestone's angular fragments interlock and pack down into a stable structural layer, which is exactly why it, not pea gravel, goes under driveways and pavers.

How much crushed limestone do I need. Calculate length times width times depth in feet, then divide by 27 for cubic yards. As a rule of thumb, one cubic yard covers about 160 to 165 square feet at 2 inches deep, or about 80 square feet at 4 inches deep. Deeper applications like driveway bases eat through material fast, so measure your actual depth requirement before ordering rather than guessing.

How crushed limestone is sold and delivered. Crushed limestone is sold in bulk by the cubic yard or by the ton and delivered by dump truck, with most suppliers setting a delivery minimum for a load. It's heavy, over a ton per cubic yard in most grades, so a half-ton pickup can typically only haul about 0.5 to 0.75 cubic yards safely per trip, which matters if you're picking up rather than having it delivered.