Terminology

• Pebble gravel / granular gravel: Udden-Wentworth classes of 4 to 64 mm and 2 to 4 mm
• USCS gravel: coarse fraction more than 50 percent retained on the No. 4 sieve (4.75 mm); groups GW, GP, GM, GC
• Pea gravel: clean gravel about the size of garden peas
• Shingle: smooth rounded beach or alluvial gravel, 20 to 200 mm
• Conglomerate: rock formed when sediment with over 30 percent gravel hardens

History and demand

Sourcing

• United States 2025: about 870 million tons of construction sand and gravel, down from about 880 million tons in 2024, valued at $12.6 billion; the top states in 2023 were Texas, California, Minnesota, Michigan, and Arizona (USGS)

Demand trend

• United States 2020: about 960 million tons of construction sand and gravel, about 23 percent of industrial mineral production by value ($12.6 billion)
• Almost half of gravel goes into concrete as aggregate; the rest is road base, road surfacing and blacktop, and construction fill
• Crushed stone is replacing natural gravel in the eastern United States, and recycled gravel is becoming more important

Composition and production

Raw materials

• Mostly weathered bedrock; quartz is the most common mineral because it is hard, chemically inert, and lacks cleavage planes
• Rivers round fragments within a few tens of kilometers of the source; gravel accumulates in stream channels, alluvial fans, near-shore marine settings, and deltas

Product forms

• Pea gravel, bank and bench gravel, crushed stone, and graded base material

Grades and types

• Other definitions: ISO 14688 grades gravel as fine (2 to 6.3 mm), medium, or coarse (20 to 63 mm); USDA uses 2 to 80 mm; the Army Corps of Engineers uses particles under 76 mm retained on the No. 4 sieve
• Crushed stone: mechanically crushed and graded rock, often granite or limestone

Properties

Physical

• Bulk density: about 1,460 to 1,920 kg/m³ (91 to 120 lb/ft³)

Thermal and moisture

• Hydraulic conductivity: natural gravel sometimes above 1 cm/s; porous deposits act as aquifers

Standards

Test methods

• ASTM D2487: soil classification (Unified Soil Classification System)

Uses in buildings

Building elements

• Slab on Grade: base under slabs
• Retaining Walls, Site Drainage: free-draining backfill
• Built-Up Roofing: aggregate surfacing embedded in the flood coat
• Site Paving: road base, surfacing, and fill

Pros and cons

Pros

• High hydraulic conductivity
• Large supply: about 960 million tons of construction sand and gravel in the United States in 2020
• Crushed forms interlock

Cons

• Gravelly soils hold little moisture and few nutrients, so plants grow sparsely
• Natural gravel is being displaced by crushed stone in parts of the United States

Manufacturing and cost

Main manufacturers and suppliers

• Vulcan Materials
• Martin Marietta
• CRH
• Heidelberg Materials

Trade association: National Stone, Sand and Gravel Association.

Sources

• Wikipedia: Gravel, https://en.wikipedia.org/wiki/Gravel
• Wikipedia: Unified Soil Classification System, https://en.wikipedia.org/wiki/Unified_Soil_Classification_System
• Wikimedia Commons: Kongensbro gravel pit 2014-09-17.jpg, photo by Slaunger (CC BY-SA 3.0), https://commons.wikimedia.org/wiki/File:Kongensbro_gravel_pit_2014-09-17.jpg
• USGS: Mineral Commodity Summaries 2026, sand and gravel (construction), https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-sand-gravel.pdf