Limestone screenings, also known as FDOT Code 21, #21 limestone, limestone fines, or crushed limestone screenings, are a finely graded aggregate typically consisting of particles approximately 3/8 inch and smaller. The blend of small angular stone, limestone dust, and fines allows the material to spread evenly and compact into a smooth, firm surface. Exact gradation may vary by approved source and project specification.
When properly placed, graded, and mechanically compacted, limestone screenings fill small voids and lock together tightly to create a stable finishing or leveling layer. Their fine texture supports precise elevation control and a clean limestone surface, making them especially useful in hardscape, paving, and construction applications where accurate grading is important.
FDOT Code 21 limestone screenings are widely used because they combine dependable compaction, easy workability, and consistent surface coverage. They perform well beneath pavers, patios, sidewalks, and walkways, and can also be used to tighten aggregate layers or prepare surfaces before final compaction.
Common Applications of Limestone Screenings (FDOT Code 21)
- Base and leveling layer beneath pavers and patios
- Sidewalk and walkway preparation
- Hardscape and retaining wall block installation
- Fine grading before final compaction
- Filling voids within larger aggregate layers
- Backfilling around utilities and small structures
- Surface smoothing over compacted base
- Residential and commercial construction preparation










