A loose collection of rock fragments is called gravel. Gravel is a byproduct of sedimentary and erosive geologic processes that occur naturally across the planet. It is also produced commercially in vast amounts as crushed stone.
Granule- to boulder-sized fragments are included in the size classes for gravel, which are categorized according to the particle size range. Granular gravel (2-4 mm) and pebble gravel are the two categories of gravel in the Udden-Wentworth scale (4–64 mm).
Gravel soil can be identified in the mid-section of soil particle size distribution. Size distribution varies starting from coarse gravel to fine gravel.
| Particle size class | Size/(mm) |
| Boulders | >200 |
| Vary coarse gravel | 200-60 |
| Coarse gravel | 60-20 |
| Medium gravel | 20-6 |
| Fine gravel | 6-2 |
| Coarse sand | 2.0-0.6 |
| Medium sand | 0.6-0.2 |
| Fine sand | 0.2-0.06 |
| Silt | 0.06-.002 |
| Clay | <0.002 |
Gravel Soil Classifications
Based on the production, existence, etc. gravel can be classified under four main types. They are,
1. Manufactured Gravel (Man Made)
Stones are crushed and filtered with the aid of large machinery to create man-made gravel. The phrase “man-made” describes how the gravel is prepared. Sharp edges make this kind of gravel ideal for work involving the paving of roads. The most popular type of man-made gravel is called granite, which is distinguished by its white particles or swirls. Smaller granite stones are utilized for attractive beds and paths, whereas larger granite stones are used for roadways and drainage systems.
2. Formed by Natural Process
The majority of gravel comes from the bedrock that has deteriorated due to weathering. Due to its hardness, chemical inertness, and absence of cleavage planes along which the rock can easily fracture quartz is the most frequent mineral found in gravel. Since few rocks have mineral grains that are coarser than roughly 8 millimeters in size, the majority of gravel particles are made up of numerous mineral grains. Quartz veins, pegmatites, substantial intrusions, and high-grade metamorphic rock are exceptions. Rivers carry the rock shards, frequently within a few tens of kilometers of their source outcrops, where they quickly circle as they travel.
3. Bank Gravel
Bank gravel is any naturally formed gravel that has been combined with sand or clay. Large stones, soil, and smaller stones are all jumbled together in bank gravel. It is used to build up areas where concrete will be laid, including driveways, as well as to fill low spots in yards.
4. Pay Dirt Gravel
Pay dirt gravel is naturally occurring gravel that is taken out when gold panning. Although it could be made of a range of rock components, this kind of gravel contains valuable metals like silver and gold.
Uses of Gravel
It is used for a variety of purposes, and it is a very useful material to us. From home gardens to construction fields, its uses are extended.
Some of the main uses of gravel are
1. Use as Construction Material
In addition to being mixed with asphalt when building roads, gravel and sand are also utilized in the production of concrete. It is frequently used to surface roads, particularly in rural regions and during freezing weather. It can also be used as the base layer for roads before being topped with tarmac. Additionally, it can be included in roof coverings.
When rendering a building’s exterior walls with pebbledash, which is a type of render in which the topcoat is textured to produce a rough surface, gravel can also be utilized. See Pebbledash for more details.
2. Landscaping Material
Gravel is frequently used in landscaping, including on roadways, and walks, and as a decorative filler on top of the soil rather than grass. The primary component used to construct driveways, patios outside, and walks are gravel. Gravel is essential to the landscape industry’s success since many homes want these features to improve curb appeal and spark enduring interest.
Because gravel prevents evaporation better than mulch does, moisture is kept in the soil beneath the gravel, allowing landscapers to better manage their water resources. In addition to its practical uses, it is employed for ornamental elements like walks, patios, and even roads.
3. Garvel for Erosion Control
Gravel can be used to filter water, acting as a natural filter to keep sand-sized particles and other precipitates that may carry contaminants under check. Gravel resists erosion by water due to its angularity and hardness.
To prevent erosion, gravel soil can be used more effectively. This indicates that it is dispersed across regions where runoff raises the risk of mudslides, such as mountain slopes and hillside areas. To lessen the flow of eroded streams, they can be deposited directly within them. Erosion is the process by which soil is removed by rainwater or tidal waters. Erosion is a major worry in several areas of the United States. Fortunately, gravel can be used to solve the problem.
