• Types of Aggregate

    | by Holly Wood

    Are you curious about the different types of aggregates and what they can do for your projects?

    From gravel to granular, it’s important to understand all of their attributes when deciding which one is right for you. Whether you’re building a driveway or creating landscaping around your new home, we’ve got all the facts and figures that will bring clarity on what kind of aggregate is best for your next building project.

    Understanding Types of Aggregate

    Aggregates, in the context of construction materials, refer to granular substances utilised for various engineering purposes.

    They form a critical component in the production of concrete and are integral to the stability, strength, and durability of numerous structures.

    Aggregates, typically sourced from natural deposits or produced through industrial processes, possess diverse characteristics that influence their applicability in distinct construction projects.

    Let’s take a deeper look at the different types below; starting with coarse aggregates.

    Coarse Aggregates

    Coarse aggregate, within the realm of construction materials, encompasses a granular substance characterised by larger particle sizes.

    These aggregates typically comprise stones, gravel, or crushed rocks exceeding 4.75 millimetres (0.187 inches) in diameter. They fulfil a pivotal role in conferring strength, stability, and longevity to construction materials, notably concrete.

    Their extensive employment in various construction domains, such as roadways, foundations, drainage systems, and structural elements, highlights their indispensability in the construction field.


    Gravel, a coarse granular building material, ranks among the most commonly employed aggregates in construction. It is characterised by its rounded shape and smooth surface texture.

    Gravel, obtained from natural deposits like riverbeds and gravel pits, is available in varying sizes.

    Its application spans a broad range, including landscaping, drainage systems, and as a foundational material for concrete structures.

    It is available as a partly rounded and irregular aggregate. We stock non-decorative pea gravel in both 10mm and 20mm bulk bags, we also stock decorative gravel in a range of colours.

    Crushed Stone

    Crushed rock, an angular aggregate material, is produced by mechanically crushing rocks or large stones. This process yields irregularly shaped fragments with rough edges that interlock when compacted.

    Crushed stone is widely employed as a base layer material for forming concrete slabs, roads, driveways, and building foundations due to its exceptional load-bearing capacity.

    Its varied size gradations offer flexibility in meeting specific project requirements.

    Recycled Aggregate

    Recycled aggregate represents a sustainable solution in the construction industry.

    It encompasses crushed recycled concrete and reclaimed asphalt pavement (RAP) that undergo processing to meet desired specifications.

    The utilisation of recycled aggregate not only reduces the burden on landfills but also aligns with environmental goals.

    This versatile aggregate material finds application in road construction, walkways, and drainage systems, among others.


    Ballast provides stability, support, and proper drainage in construction, specifically in the context of railway tracks and roadways.

    It consists of a layer of coarse aggregate material, typically a blend of sand, stone, and gravel, that construction workers place beneath the track or roadbed.

    Its primary function is to evenly distribute the load from the tracks or road, spreading the weight over a larger area and reducing the risk of settlement or deformation.

    Fine Aggregate

    Fine aggregates play a crucial role in creating all kinds of durable concrete structures.

    Everyone from cement mixers to architects around the world understands that the properties of fine aggregates will determine how well a structure holds up over time.

    With dozens of potential aggregate materials out there, project planners must be careful to make informed decisions that prioritise quality and safety.

    Let’s take a deeper look at two popular fine aggregates below.


    Sand, a fine aggregate, occupies a prominent position in construction endeavours.

    Comprising individual particles smaller than gravel, sand is derived from natural sources such as riverbeds, beaches, and deserts.

    Its unique properties, including particle size and shape, significantly impact the workability and strength of concrete and mortar mixtures.

    Sand finds extensive use in construction projects, contributing to the formation of stable foundations, flooring, and plasterwork.

    Grano Dust

    Grano dust, also known as “building dust,” refers to a material comprising finer particles that are commonly used in construction projects.

    This type of aggregate is characterised by its finely crushed composition, with particles typically smaller than traditional coarse aggregates.

    In various building projects, grano dust finds frequent employment when a smoother and more compact material is desired.

    Its finer particle size allows for better compaction and levelling, making it suitable for creating a solid base for paving, driveways, and pathways.

    Practical Applications of Aggregates

    Aggregates play a pivotal role in diverse construction projects, offering a wide range of applications and benefits. Some notable practical applications include:

    • Road Construction: Aggregates provide a stable foundation, enhance drainage, and improve skid resistance on road surfaces.
    • Sub Bases: Aggregates such as crushed concrete are a cost-effective option for creating sub-bases among many other applications.
    • Building Foundations: Aggregates contribute to the structural integrity, stability, and load-bearing capacity of building foundations.
    • Landscaping and Decorative Purposes: Aggregates enhance the aesthetic appeal of landscapes by creating visually appealing pathways, gardens, and water features.
    • Drainage Systems: Aggregates facilitate proper water drainage, preventing soil erosion and maintaining the integrity of infrastructure.
    • Sports Fields and Golf Courses: Aggregates form the foundation for sports fields, golf courses, and running tracks, ensuring optimal playing conditions.
    • Railways and Airport Runways: Aggregates provide stability and load-bearing capabilities in the construction of railway tracks and airport runways, ensuring safe and efficient transportation.

    Factors Influencing Aggregate Selection

    Choosing the most appropriate aggregate for a specific project necessitates consideration of various factors.

    Key considerations include:

    1. Project Requirements: Assessing the project’s nature, load requirements, and environmental conditions aids in selecting an aggregate that fulfils the project’s specific needs.
    2. Particle Size and Gradation: Particle size distribution affects the workability and strength of the resulting concrete or other construction materials. Understanding the optimal size and gradation for a particular project is crucial.
    3. Durability and Longevity: Evaluating an aggregate’s resistance to weathering, degradation, and chemical reactions ensures the long-term durability and performance of the construction material.
    4. Availability and Proximity: Considering the proximity of aggregate sources to the project site helps minimise transportation costs and ensures a consistent supply throughout the construction process.
    5. Sustainability: Increasingly, sustainable practices are becoming vital in construction. Opting for recycled aggregates and environmentally friendly alternatives reduces the environmental impact and aligns with sustainability goals.


    As established, aggregates can come in many shapes, sizes, textures, and forms. Whether you’re looking for crushed gravel for a driveway or just a nice pebble to accessorise your garden pond, there is an aggregate out there perfect for whatever your needs may be.

    All this variety means there really isn’t a one-size-fits-all solution when it comes to choosing the perfect aggregate. Instead, you must consider the technical and aesthetic elements of each one and its application.

    Hopefully, this article helped clarify some of the more varied aspects of aggregates and what each type brings to the proverbial construction table!

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