Coarse aggregate is a fundamental material in civil engineering and is widely used in roads, bridges, dams and other basic engineering structures. It is important to understand the properties of coarse aggregates when used in civil engineering. This article aims to introduce civil engineers to the various types, uses and testing methods of coarse aggregates.
In the United States alone, more than 26 million tons of coarse aggregates are produced each year. Coarse aggregate, also called crusher aggregate or quarry aggregate, is any crushed stone less than 10 centimeters in diameter. They are used for sidewalks, road construction, and substructures for sidewalks and building foundations.
The different types of coarse rock include gravel (composed mainly of rounded stones), stone with sand-sized particles, and stone with mud-sized particles. If you have a driveway, sidewalk or parking lot that needs work, consider using coarse stone to make the job easier.
This material is easily compacted and can withstand heavy use without breaking down as quickly as asphalt. Asphalt can also crack over time if it freezes in the winter or expands due to heat in the summer. However, coarse aggregates don't break down as easily because they aren't as soft as asphalt.
Coarse aggregate is an important component of concrete because it creates a strong bond between the cement paste and finer materials such as pebbles or sand. The combination of these two elements creates a durable and stable building material.
Types of Coarse Aggregate
There are four main types of coarse aggregates:
1) Gravel
2) Gravel
3) scum
4) Recycled concrete
Gravel is classified according to its particle size. It is further divided into different types, including riverine gravel, bank gravel and gravel. River gravel or river gravel is gravel deposited by a river or other body of water. It usually consists of rounded river-worn stones mixed with smaller stones and fine grains. Bank gravel is gravel that has been deposited naturally on the slope of a valley or other depression. It usually consists of angular or irregular stones mixed with smaller stones and fine grains.
Gravel is gravel that has been crushed or pulverized by a crusher. It is further divided into different types, including crushed gravel, crushed stone and crushed slag.
Slag is a byproduct of metal smelting or processing. It typically consists of angular or irregular stones mixed with smaller, finer stones. Slag is a great alternative to gravel for use in foundations and other engineering structures because it is more resistant to weathering and compaction.
Recycled concrete is a material commonly used in civil engineering projects. It is made up of cement, sand, gravel and water. Recycled concrete can be used as a replacement for new concrete in many applications. It is a sustainable material that can help reduce the environmental impact of civil engineering projects.
Recycled concrete can be used as aggregate in new concrete. It can also be used as a base material for roads, parking lots and other foundations. Recycled concrete is a sustainable material that can help reduce the environmental impact of civil engineering projects.
Coarse aggregate properties
The properties of coarse aggregate are influenced by the size and shape of the individual particles. For example, when sand is used as coarse aggregate, it has a different effect on the pavement than gravel or crushed stone of the same size.
If the aggregate is coarse, less water rinsing will be required to remove the cement paste, reducing energy consumption. These coarse aggregates occur in nature or are produced by crushing hard materials such as stones. Among these fine aggregates, there are three main types, namely crushed stone, gravel and sand.
Gravel is made up of large particles extracted from natural rock formations, generally between 50 mm and 250 mm (2-10 inches) in diameter. The size of the gravel particles varies depending on the type of gravel used.
This type is mainly used for general construction and road construction purposes. Coarsely crushed stone has a particle size between 20 mm (0.8 in) and 64 mm (2.5 in). It can be made from various raw materials, such as granite, basalt, limestone, quartzite, etc.
In addition to its use in road construction, coarse crushed stone can also be used in concrete mixtures, adding strength and durability to concrete structures, such as buildings and bridges. Sand is one of the most common types of aggregate, found in nature or produced by crushing stones with small grains, typically below 64 mm (2 5/8 inches).
Some of the important properties of aggregates need to be considered below.
- Size and shape of aggregates: Depending on the type of construction, the size of the aggregate is determined. Different forms of the aggregate are explained below.
- Surface condition: Must be taken into consideration in terms of water absorption, etc.
- Apparently density
- specific weight
- Water absorption
- Strength
- Thermal properties
And many other properties are checked during construction. The limits for each of these properties must be in accordance with the project specification or appropriate standard.
Shape-based classification type
1) Rounded aggregates
2) Angular aggregates
3) Irregular aggregates
4) Elongated aggregates
5) Flaky aggregates
6) Scaly and elongated aggregates
Use of coarse aggregate
Among the numerous uses we can highlight some of the following important ones.
- Improve the strength of the material or use it to improve the strength of the material combination
- In concrete, aggregate is used as a filler without affecting strength.
- Coarse aggregates are used to distribute the load evenly. This can be observed, for example, in railway lines, road construction, etc.
- Water filtration
- Used in rainwater collection
- It can be used to inject rainwater into the soil.
The article Types of tests for aggregates Information on the available tests to be carried out on the aggregate when used in the structure can be consulted depending on the type of use. We may not require all tests to be carried out, but they will be able to do so if necessary.
