onstructing a building is not as simple as you think. The resources need several careful considerations, and one of them is soil. It holds immense importance in the structure’s stability and durability throughout its lifetime.
You might have knowledge about various types of soil, but making an informed decision matters more to ensure a solid foundation. To relieve you from stressful situations, we come to talk about a recognized soil type—gravel. It is widely used for long-lasting structural integrity and stability that suits well with your construction requirements.
To make you more clear, we have explained to you its classifications, types, benefits, and applications. You can stay a bit longer to gather some more significant points.
What is Gravel
Gravel is a loose group of rock fragments containing a vast amount of gravel particles, including rocks and stones. They are generally larger than sand and tinier than cobbles, ranging from 4.75mm to 75 mm in diameter. The gravel forms through naturally occurring processes like weathering and erosion, often produced by crushing larger stones into soil at quarries. It seems like a rough, rocky texture that has a larger space between the particles, allowing water to move freely.
Classification of Gravel
As per the Indian Standard IS 1498:1970 -Classification And Identification of Soils for General Engineering Purposes, gravel is broadly classified based on the various characteristics and are as follows:
Well-Graded Gravel: The particle sizes are evenly distributed from larger to smaller. It provides excellent interlocking with minimal void spaces. For a gravel to be classified as well-graded, it should include less than 5% fine particles.
Poorly-Graded Gravel: In contrast to well-graded gravel, it contains either a single size or a narrow range of sizes. It also has less than 5% fine particles, but will be resulting in lower stability and higher void content.
Clayey Gravel: This type of gravel contains more than 12% fines, with the fines exhibiting low to high plasticity—indicating the presence of clay. Due to its cohesive nature and low permeability, clayey gravel is not suitable for drainage applications but may be used in situations where stability and cohesion are required.
Silty Gravel: Silty gravel also contains more than 12% fines, but these fines show little to no plasticity, indicating the presence of silt rather than clay. It has relatively low permeability and is typically not preferred for drainage purpose.
Types of Gravel
Here are the lists of gravel types, which are applied to different building requirements based on the project needs:
Uncrushed Gravel: This is a naturally occurring gravel identified in rounded or sub-rounded shape due to erosion and transport. It is the result of natural disintegration of rock, recognized for its smooth surface texture and better workability. Though it is rounded, it carries slightly less interlocking capacity compared to angular aggregates.
Crushed Gravel: It is produced by crushing naturally occurring larger or hard stones. Unlike even or round shape, it may result in irregular, rough-textured or angular particles. It carries superior interlocking, and higher strength, suitable for pavement layers and high-density concrete.
Partially Crushed Gravel: It is a mixture of uncrushed and crushed gravel or stone. They offer a balanced set of properties, an ideal choice to optimize concrete workability for achieving adequate strength and particle interlocking.
Applications of Gravel in Construction
Gravel is a versatile construction material; hence, it is used in different applications such as
Road Construction: By mixing gravel with asphalt, you can create sturdy road surfaces, particularly used in rural regions and places with severe cold conditions. It provides strong and flexible ground cover to roads and driveways, preventing cracking on the surface.
Concrete Making: Gravel is a prominent component to be used in the production of concrete, offering exceptional strength and durability to the building. It also includes materials like cement, water, and sand to form a quality and solid construction material.
Foundation Material: Gravel becomes a great choice to lay as a base layer for foundations. It actively prevents water accumulation and critical damage to the structure. This material also provides stable and well-draining surfaces to areas like driveways, buildings, and roads.
Landscaping: Beyond its strength and durability, gravel is widely recognized for its aesthetic purposes. If you are looking to give an attractive transformation to your construction, consider this option. It actively prevents drainage troubles and soil erosion in and around the structure.
Benefits of Using Gravel
Gravel provides several advantages to the construction, and some of them are
- Gravel is available in various sizes and colors that help elevate the overall look and visual appearance of any landscape design.
- The primary function of gravel is to drain the water wall, which actively prevents water accumulation and keeps the construction safe in any harsh climatic conditions.
- Being a strong and durable material, gravel is easy to maintain and a cost-effective method for various building projects.
- Gravel helps to drain out the water completely and seep into the ground, thereby we can recharge underground water levels in an eco-friendly manner.
Properties of Gravel
Let’s uncover some key properties of gravel:
- Gravel is typically larger than sand that includes rocks and pebbles, with sizes ranging between 4.75 to 75mm.
- Due to its high permeability and larger pores, gravel has an amazing drainage system. It allows water to travel underground easily.
- Gravel has hard and angular particles, which makes it highly resistant to water and wind.
- Gravel is non-cohesive and has a moderate bulk density that ranges from 1,400 to 1,700 kg/m³.
- Gravel provides excellent strength and stability to buildings and is used as a base layer for roads and other constructions.
Considerations When Using Gravel
The usage of gravel differs based on the construction applications. Herewith, some of the common significant factors are listed that need to be kept in mind:
Gravel Size: The gravel size and distribution over the surface directly influence its performance. If it is a well-graded gravel, you can expect higher strength, stability, and lower permeability, whereas the uniformly sized gravel leads to instability and settlement.
Presence of Fines: Determine the type and amount of finer particles mixed within the gravel. If they are excessively fine, the gravel is highly susceptible to frost heave and lower bearing capacity.
Drainage Capacity: Gravel is highly permeable, which works excellently in a drainage system. Ensuring the gravel has fewer fines can significantly improve the water accumulation and drainage capacity.
Source and Quality: The geological source of gravel stones significantly impacts their performance, like shape, hardness, and durability. To ensure the quality of the material, the gravel should be free from organic matter and other deleterious materials.
Water Absorption: It indicates how much water that the gravel needs to soak up to achieve a sponge state. If it absorbs too much water, it steals water content from the concrete mix and makes the construction weaker. Generally, the water absorption capacity should be less than 2 – 3% for a good concrete.
Impact Value: It measures how tough the gravel is. A gravel used in floors and road surfaces should have an impact value of less than 30%. For gravel in other construction work can range up to 45%. The lower the percentage, the tougher the gravel will be.
Last Few Lines
Gravel is a stable and long-lasting material that plays a crucial role in various construction applications. Choosing the right soil type from the right source can improve your building’s strength and stability. Furthermore, it effectively drains out the water and reduces the risk of water-related erosion and damage. More than its strength and durability, it elevates the aesthetic appearance and functionality of the overall structure.